JP7619283B2 - Light-emitting member, light-emitting compound, and photoelectric conversion member - Google Patents

Description

The present invention relates to light-emitting components, light-emitting compounds and photoelectric conversion components, and more specifically to light-emitting components and the like that can achieve a high luminescence quantum yield in the long-wavelength near-infrared region, which contain a light-emitting compound that can emit light in the long-wavelength region of near-infrared light (hereinafter also referred to as the "long-wavelength near-infrared region") and can be incorporated into components at high concentrations.

Near-infrared light-emitting materials have attracted attention because they allow the background effect of autofluorescence from living cells to be ignored under near-infrared excitation, and because near-infrared light is less scattered inside the body than visible light, they enable imaging deeper within the body, biometric authentication using vein imaging, and biomeasurements such as pulse oximeters. For this reason, compounds that emit light in the near-infrared region are being investigated.

However, it is generally known that the use of compounds with emission wavelengths longer than the visible light region results in a drastic drop in luminescence quantum yield. This is because near-infrared emission has low excited state energy, which increases the effect of non-radiative deactivation due to molecular vibration. Furthermore, when the conjugated system of the dye is expanded to lengthen the emission wavelength, the intermolecular interactions increase, which makes the dye more likely to aggregate in thin films or particles, resulting in concentration quenching. Therefore, even if a luminescent dye exhibits near-infrared emission with a high luminescence quantum yield in solution, there is a problem in that a high luminescence quantum yield cannot be maintained when the dye is dispersed in a solid matrix such as a resin.

Squarylium compounds are known as near-infrared absorbing materials (see, for example, Patent Document 1). It is also known that squarylium compounds are used in combination with delayed fluorescent materials or phosphorescent compounds in organic electroluminescence devices (see, for example, Patent Document 2). However, there have been no studies to date on the molecular structure of squarylium compounds from the viewpoint of obtaining a high luminescence quantum yield even when contained at a high concentration for the purpose of application to light-emitting components.

International Publication No. 2017/130825 International Publication No. 2018/008721

The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide a light-emitting component that can achieve a high light emission quantum yield in the long near-infrared wavelength region by containing a light-emitting compound that can emit light in the long near-infrared wavelength region and be incorporated into components at a high concentration. In addition, it is to provide a light-emitting compound that can emit light in the long near-infrared wavelength region and be incorporated into components at a high concentration. Furthermore, it is to provide a photoelectric conversion component that can obtain high external quantum efficiency by using a light-emitting compound that can emit light in the long near-infrared wavelength region and be incorporated into components at a high concentration.

In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that in a compound having a squarylium ring at the center of its molecular structure, by forming a molecular structure having an emission peak in the long-wavelength near-infrared region and arranging soluble groups on the outer groups of the squarylium ring so that they extend in a direction toward the squarylium ring, the compound will emit light in the long-wavelength near-infrared region while mitigating concentration quenching, enabling it to be incorporated into a matrix at a high concentration, which led to the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

［一般式（Ｔ２）において、
Ａ～Ｌは、それぞれ独立して、芳香族炭化水素環を表す。
ｎ１～ｎ６は、それぞれ独立して、０又は１の整数を表す。
Ｙａ及びＹｂは、それぞれ独立して、ＯＨ基、ＮＨＣＯＲａ（Ｒａは炭化水素基を表す。）基、ＮＨＳＯ_２Ｒｂ（Ｒｂは炭化水素基を表す。）基、又はＮＨＰＯ（ＯＲｆ）（ＯＲｇ）（Ｒｆ及びＲｇはそれぞれ炭化水素基を表す。）基を表す。
Ｙｃ～Ｙｌは、それぞれ独立して、水素原子又は置換基を表す。
ただし、Ｙａ及びＹｂのうち少なくとも１つは、炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を含む基である。

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ_５１は水素原子又はメチル基を表す。）］ 1. A light-emitting member containing a compound having a structure represented by the following general formula (T 2 ):

[In the general formula (T 2 ),
A to L each independently represent an aromatic hydrocarbon ring .
Each of n1 to n6 independently represents an integer of 0 or 1 .
Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group).
Yc to Yl each independently represent a hydrogen atom or a substituent.
However, at least one of Ya and Yb is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the following general formula (P):

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

2. The light-emitting member according to item 1, wherein in the general formula (T 2 ), at least one of Y e to Y l is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the general formula (P).

（一般式（１ｂ）において、各Ｒａは、それぞれ独立して、炭化水素基を表す。各Ｒｃは、それぞれ独立して、水素原子又は置換基を表す。２個のＲａのいずれかが炭素数４～１２の直鎖状又は分岐状のアルキル基（ａ）を表すか、４個のＲｃのうち少なくとも１個が、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を表す。） 3. A light-emitting member containing a compound having a structure represented by the following general formula (1b):

(In general formula (1b), each Ra independently represents a hydrocarbon group. Each Rc independently represents a hydrogen atom or a substituent. Either of two Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Rc's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by general formula (P).)

（一般式（１ｄ）において、各Ｒａは、それぞれ独立して、炭化水素基を表す。各Ｒｅは、それぞれ独立して、水素原子又は置換基を表す。各Ｘａは、それぞれ独立して、炭素数１～３のアルキル基若しくはアルコキシ基又は置換又は無置換のフェニル基を表し、４位に結合する場合のＸａは、下記式（Ｄ）で表される構造を有する基であってもよい。ｍは、０～４の整数を表す。ただし、一般式（１ｄ）においては、２個のＲａのいずれかが炭素数４～１２の直鎖状又は分岐状のアルキル基（ａ）を表すか、４個のＲｅのうち少なくとも１個が、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を表すか、又は前記４位にＸａとして下記式（Ｄ）で表される構造を有する基が結合する。）

（式（Ｄ）において、※は接続部位を示す。Ｘ _３１ ～Ｘ _３５ は、それぞれ独立して、水素原子又は置換基を表す。ただし、Ｘ _３１ 及びＸ _３５ のうち少なくとも１つは炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を有する基であり、Ｘ _３２ ～Ｘ _３４ は、炭素数４以上の直鎖状若しくは分岐状のアルキル基又は（ポリ）オキシアルキレン基を有しない。）］

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ _５１ は水素原子又はメチル基を表す。）］ 4. A light-emitting member containing a compound having a structure represented by the following general formula (1d):

(In general formula (1d), each Ra independently represents a hydrocarbon group. Each Re independently represents a hydrogen atom or a substituent. Each Xa independently represents an alkyl group or an alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group, and Xa bonded to the 4th position may be a group having a structure represented by the following formula (D). m represents an integer of 0 to 4. However, in general formula (1d), either of two Ra represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Re represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the above general formula (P), or a group having a structure represented by the following formula (D) is bonded to the 4th position as Xa.)

(In formula (D), * denotes a connecting site. X ₃₁ to X ₃₅ each independently represent a hydrogen atom or a substituent. However, at least one of X ₃₁ and X ₃₅ is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group having a group (P) having a structure represented by the following general formula (P), and X ₃₂ to X ₃₄ do not have a linear or branched alkyl group having 4 or more carbon atoms or a (poly)oxyalkylene group.)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

5. The light-emitting member according to any one of items 1 to 4 , wherein the light-emitting member is a light-emitting thin film.

6. The light-emitting member according to any one of items 1 to 4 , wherein the light-emitting member is a light-emitting particle.

（一般式（１ａ）において、各Ｒｃは、それぞれ独立して、水素原子又は置換基を表し、４個のＲｃのうち少なくとも１個は、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を表す。）

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ_５１は水素原子又はメチル基を表す。） 7. A light-emitting compound having a structure represented by the following general formula (1a):

(In general formula (1a), each Rc independently represents a hydrogen atom or a substituent, and at least one of the four Rc represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the following general formula (P).)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

（一般式（１ｂ）において、各Ｒａは、それぞれ独立して、炭化水素基を表す。各Ｒｃは、それぞれ独立して、水素原子又は置換基を表す。２個のＲａのいずれかが炭素数４～１２の直鎖状又は分岐状のアルキル基（ａ）を表すか、４個のＲｃのうち少なくとも１個が、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を表す。）

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ_５１は水素原子又はメチル基を表す。） 8. A light-emitting compound having a structure represented by the following general formula (1b):

(In general formula (1b), each Ra independently represents a hydrocarbon group. Each Rc independently represents a hydrogen atom or a substituent. Either of two Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Rc's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the following general formula (P).)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

［一般式（Ｔ）において、
Ａ～Ｌは、それぞれ独立して、芳香族炭化水素環又はヘテロ芳香環を表す。
ｎ１～ｎ６は、それぞれ独立して、０～２の整数を表す。
Ｙａ及びＹｂは、それぞれ独立して、ＯＨ基、ＮＨＣＯＲａ（Ｒａは炭化水素基を表す。）基、ＮＨＳＯ_２Ｒｂ（Ｒｂは炭化水素基を表す。）基、又はＮＨＰＯ（ＯＲｆ）（ＯＲｇ）（Ｒｆ及びＲｇはそれぞれ炭化水素基を表す。）基を表す。
Ｙｃ～Ｙｌは、それぞれ独立して、水素原子又は置換基を表す。
ただし、Ｙａ～Ｙｌのうち少なくとも１つは、炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を含む基である。

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ_５１は水素原子又はメチル基を表す。）］ 9. A photoelectric conversion member containing a compound having a structure represented by the following general formula (T):

[In the general formula (T),
A to L each independently represent an aromatic hydrocarbon ring or a heteroaromatic ring.
n1 to n6 each independently represent an integer of 0 to 2.
Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group).
Yc to Yl each independently represent a hydrogen atom or a substituent.
However, at least one of Ya to Yl is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the following general formula (P):

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

By the above-mentioned means of the present invention, it is possible to provide a light-emitting component that can achieve a high light emission quantum yield in the near-infrared long wavelength region, containing a light-emitting compound that can emit light in the near-infrared long wavelength region and be incorporated into components at a high concentration. It is also possible to provide a light-emitting compound that can emit light in the near-infrared long wavelength region and be incorporated into components at a high concentration. Furthermore, it is possible to provide a photoelectric conversion component that can obtain a high external quantum efficiency by using a light-emitting compound that can emit light in the near-infrared long wavelength region and be incorporated into components at a high concentration.

Although the mechanism by which the effects of the present invention are expressed or acted upon has not been clarified, it is speculated as follows.

A compound having a structure represented by general formula (T) (hereinafter also referred to as compound (T)) is a compound having a squarylium ring at the center of its molecular structure. Compound (T) has a structure in which nitrogen atoms are bonded to the left and right of a squarylium ring via an aromatic hydrocarbon ring or a heteroaromatic ring in the main skeleton, and two aromatic hydrocarbon rings or heteroaromatic rings are bonded to the nitrogen atoms. Note that these aromatic hydrocarbon rings or heteroaromatic rings also include a structure in which two or three are linked in a chain. In addition, compound (T) has an OH group, an NHCORa group, an NHSO ₂ Rb group, or an NHPO(ORf)(ORg) group at a predetermined position on the aromatic hydrocarbon ring or heteroaromatic ring bonded to the squarylium ring. Furthermore, compound (T) has a structure in which a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group (P) having a structure represented by the above general formula (P), as a soluble group, is bonded to the above aromatic hydrocarbon ring or heteroaromatic ring directly or via a linking group such that the group is positioned in a direction toward the central squarylium ring.

By giving the squarylium compound the above-mentioned molecular structure possessed by compound (T), the inventors have achieved a molecular structure having an emission peak in the long wavelength region of near-infrared light, while mitigating concentration quenching, enabling incorporation into the matrix at high concentrations.

［一般式（１）において、
Ｌ _１ は下記式（Ｌ１）、式（Ｌ２）又は式（Ｌ３）で表される構造を有する基を表す。Ｌ _２ は下記式（Ｌ４）、式（Ｌ５）又は式（Ｌ６）で表される構造を有する基を表す。

（式（Ｌ１）～式（Ｌ６）において、
※１及び※４はそれぞれ一般式（１）のＮに結合する部位を表す。※２及び※３はそれぞれ一般式（１）のスクアリリウム環の炭素に結合する部位を表す。
Ｒ _１ 、Ｒ _５ 、Ｒ _２１ 及びＲ _２７ は、それぞれ独立して、ＯＨ基、ＮＨＣＯＲａ（Ｒａは炭化水素基を表す。）基、ＮＨＳＯ _２ Ｒｂ（Ｒｂは炭化水素基を表す。）基、又はＮＨＰＯ（ＯＲｆ）（ＯＲｇ）（Ｒｆ及びＲｇはそれぞれ炭化水素基を表す。）基を表す。
Ｒ _２ ～Ｒ _４ 、Ｒ _６ ～Ｒ _８ 、Ｒ _１１ ～Ｒ _１８ 、Ｒ _２２ ～Ｒ _２６ 及びＲ _２８ ～Ｒ _３２ は、それぞれ独立して、水素原子又は置換基を表す。）
Ａｒ _１ ～Ａｒ _４ は、それぞれ独立して、下記式（Ａ）、式（Ｂ）又は式（Ｃ）で表される構造を有する基を表す。

（式（Ａ）～式（Ｃ）において、※はＮ原子との接続部位を示す。Ｘ _１ ～Ｘ _２７ は、それぞれ独立して、水素原子又は置換基を表す。）
ただし、一般式（１）において、Ｌ _１ 、Ｌ _２ 及びＡｒ _１ ～Ａｒ _４ のいずれかは、以下の所定の位置の少なくとも１つに、炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を有する。
Ｌ _１ 又はＬ _２ における前記所定の位置は、Ｒ _１ 、Ｒ _５ 、Ｒ _２１ 及びＲ _２７ がＮＨＣＯＲａ基の場合のＲａ（ただし、基（Ｐ）は除く）、Ｒ _１ 、Ｒ _５ 、Ｒ _２１ 及びＲ _２７ がＮＨＳＯ _２ Ｒｂ基の場合のＲｂ（ただし、基（Ｐ）は除く）、Ｒ _１ 、Ｒ _５ 、Ｒ _２１ 及びＲ _２７ がＮＨＰＯ（ＯＲｆ）（ＯＲｇ）基の場合のＲｆ又はＲｇ（ただし、基（Ｐ）は除く）、Ｒ _２ 、Ｒ _１１ 、Ｒ _１２ 、Ｒ _６ 、Ｒ _１５ 、Ｒ _１６ 、Ｒ _２６ 、及びＲ _３２ である。
Ａｒ _１ ～Ａｒ _４ における前記所定の位置は、Ｘ _１ 、Ｘ _５ 、Ｘ _１１ 、Ｘ _２１ 及びＸ _２７ 並びに下記式（Ｄ）のＸ _３１ 及びＸ _３５ である。
さらに、一般式（１）において、Ｌ _１ 又はＬ _２ における、Ｒ _３ 、Ｒ _４ 、Ｒ _１３ 、Ｒ _１４ 、Ｒ _２３ 、Ｒ _２４ 、Ｒ _２５ 、Ｒ _７ 、Ｒ _８ 、Ｒ _１７ 、Ｒ _１８ 、Ｒ _２９ 、Ｒ _３０ 及びＲ _３１ 、Ａｒ _１ ～Ａｒ _４ における、Ｘ _２ 、Ｘ _３ 、Ｘ _４ 、Ｘ _１２ 、Ｘ _１３ 、Ｘ _１４ 、Ｘ _１５ 、Ｘ _２２ 、Ｘ _２３ 、Ｘ _２４ 及びＸ _２５ は、炭素数４以上の直鎖状若しくは分岐状のアルキル基又は（ポリ）オキシアルキレン基を有しない。ただし、Ｘ _３ 、Ｘ _１３ 及びＸ _２４ は、下記式（Ｄ）で表される構造を有する基であってもよい。

（式（Ｄ）において、※は接続部位を示す。Ｘ _３１ ～Ｘ _３５ は、それぞれ独立して、水素原子又は置換基を表す。ただし、Ｘ _３１ 及びＸ _３５ のうち少なくとも１つは炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を有する基であり、Ｘ _３２ ～Ｘ _３４ は、炭素数４以上の直鎖状若しくは分岐状のアルキル基又は（ポリ）オキシアルキレン基を有しない。）］

（一般式（１ｃ）において、各Ｒｄは、それぞれ独立して、水素原子又は置換基を表し、４個のＲｄのうち少なくとも１個は、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を表す。各Ｘａは、それぞれ独立して、炭素数１～３のアルキル基若しくはアルコキシ基又は置換又は無置換のフェニル基を表す。ｍは、０～４の整数を表す。）

（一般式（１ｅ）において、Ｙａ及びＹｂは、それぞれ独立して、ＯＨ基、又はＮＨＣＯＲａ（Ｒａは炭化水素基を表す。）基を表す。各Ｒｅは、それぞれ独立して、水素原子又は置換基を表す。各Ｘａは、それぞれ独立して、炭素数１～３のアルキル基若しくはアルコキシ基、又は置換又は無置換のフェニル基を表す。ｍは、０～３の整数を表す。ただし、Ｒａのいずれかが炭素数４～１２の直鎖状又は分岐状のアルキル基（ａ）を表すか、又は４個のＲｅのうち少なくとも１個は、連結基として－Ｏ－を有してもよい炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は前記一般式（Ｐ）で表される構造を有する基（Ｐ）を表す。） In the present invention, by incorporating the compound (T) into the light-emitting component, a light-emitting component capable of achieving a high light-emitting quantum yield in the near-infrared long wavelength region can be obtained. In addition, in order to achieve such an effect, among the compounds (T), a compound having a structure represented by the following general formula (1) (hereinafter also referred to as compound (1)) is particularly preferable. In the compound (1), the compound having the above-mentioned specific molecular structure, that is, the compound having the structure represented by the general formula (1a), (1b), or (1d) or the following general formula (1c) or (1e) is a novel compound that has not been described in the literature so far.

[In the general formula (1),
L1 represents a group having a structure represented by the following formula (L1), (L2) or (L3), _{L2 represents} a group having a structure represented by the following formula (L4), (L5) or (L6).

(In formulas (L1) to (L6),
*1 and *4 respectively represent the sites of bonding to N in general formula (1). *2 and *3 respectively represent the sites of bonding to the carbon of the squarylium ring in general formula (1).
R ₁ , R ₅ , R ₂₁ and R ₂₇ each independently represent an OH group, an NHCORa group (wherein Ra represents a hydrocarbon group), an NHSO ₂ Rb group (wherein Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (wherein Rf and Rg each represent a hydrocarbon group).
R ₂ to R ₄ , R ₆ to R _{8 ,} R ₁₁ to R ₁₈ , R ₂₂ to R ₂₆ and R to R ₃₂ each independently represent a hydrogen atom or a substituent.
Ar ₁ to Ar ₄ each independently represent a group having a structure represented by the following formula (A), formula (B) or formula (C).

(In formulae (A) to (C), * indicates a connection site with an N atom. X ₁ to X ₂₇ each independently represent a hydrogen atom or a substituent.)
In general formula (1), any of L ₁ , L ₂ and Ar ₁ to Ar ₄ has a linear or branched alkyl group (a) having 4 to 12 carbon atoms or a group (P) having a structure represented by general formula (P) at at least one of the following specified positions:
The predetermined positions in L1 or L2 _are Ra (excluding group (P)) when R1, R5, R21 and R27 are NHCORa groups, Rb (excluding group (P)) when R1 _, R5 _, R21 _and R27 _{are NHSO2Rb groups ,} Rf _or Rg ₍ excluding group (P)) when R1 _{, R5, R21 and R27 are} NHPO ₍ ORf ₎ ( _ORg ) groups , _R2 , _R11 , _{R12 , R6} , R15 , _R16 , _R26 and _R32 .
The predetermined positions in Ar ₁ to Ar ₄ are X ₁ , X ₅ , X ₁₁ , X ₂₁ and X ₂₇ , as well as X ₃₁ and X ₃₅ in the following formula (D) .
Furthermore , in general formula (1), _R 3 _, R ₄ , R ₁₃ , R ₁₄ , R ₂₃ , R ₂₄ , R ₂₅ , R ₇ , R ₈ , R ₁₇ , R ₁₈ , R ₂₉ , R ₃₀ and R ₃₁ in L 1 or L 2, and X 2 , X 3 , X 4 , X 12 , X 13 , X 14 , X 15 , X 22 , X 23 , X 24 and X 25 in Ar ₁ to Ar _{4 do} not _have a linear _or branched _{alkyl group} or _a ( _poly ) _oxyalkylene group _having 4 _or more _{carbon atoms} . However, X ₃ , X ₁₃ and X ₂₄ may be a group having a structure represented by the following formula (D).

(In formula (D), * denotes a connecting site. X ₃₁ to X ₃₅ each independently represent a hydrogen atom or a substituent. However, at least one of X ₃₁ and X ₃₅ is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group having a group (P) having a structure represented by general formula (P), and X ₃₂ to X ₃₄ do not have a linear or branched alkyl group having 4 or more carbon atoms or a (poly)oxyalkylene group.)

(In general formula (1c), each Rd independently represents a hydrogen atom or a substituent, and at least one of the four Rds represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by general formula (P). Each Xa independently represents an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group. m represents an integer of 0 to 4.)

(In general formula (1e), Ya and Yb each independently represent an OH group or an NHCORa group (Ra represents a hydrocarbon group). Each Re each independently represents a hydrogen atom or a substituent. Each Xa each independently represents an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group. m represents an integer from 0 to 3. However, any of the Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of the four Re's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the general formula (P).)

Furthermore, when compound (T) is used in a photoelectric conversion element, a photoelectric conversion element with high external quantum efficiency can be obtained. This is presumably because compound (T), especially compound (1), has the characteristic of having an emission peak in the long wavelength near infrared region and exhibiting a high emission quantum yield, which makes it difficult for excitons to pass through quenching paths such as non-radiative deactivation when molecules are excited, resulting in such an effect.

This is ^{the 1} H-NMR spectrum (400 MHz, measurement solvent: CDCl3) of compound (1a)-1. This is ^{the 1} H-NMR spectrum (400 MHz, measurement solvent: CDCl3) of compound (1c)-1. This is ^{the 1} H-NMR spectrum (400 MHz, measurement solvent CDCl3) of compound (1d)-1. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an infrared emitting surface light source using a wavelength conversion film having a light emitting member of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a wavelength conversion film provided with a light emitting member of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an organic photoelectric conversion element including the photoelectric conversion member of the present invention.

The light-emitting component of the present invention is characterized in that it contains a compound having a structure represented by the above general formula (T). This characteristic is a technical feature common to each of the following embodiments.

In an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, it is preferable that in the above general formula (T), A to L represent an aromatic hydrocarbon ring, n1 to n6 are each independently 0 or 1, and at least one of Ya and Yb is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the above general formula (P).

In an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, it is preferable that in the above general formula (T), A to L represent an aromatic hydrocarbon ring, n1 to n6 are each independently 0 or 1, and at least one of Ye to Yl is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the above general formula (P).

In an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, it is preferable that the structure represented by the above general formula (T) is a structure represented by the above general formula (1).

A compound having a structure represented by general formula (1) (hereinafter also referred to as compound (1)) has a structure in which nitrogen atoms are bonded to the left and right of a squarylium ring via a benzene ring, a biphenyl ring, or a naphthalene ring, and two benzene rings or naphthalene rings are bonded to the nitrogen atom. Compound (1) is a compound in which the bonding position of a linear or branched alkyl group (a) having 4 to 12 carbon atoms, which compound (T) has as a soluble group, or a group (P) having a structure represented by the above general formula (P), is specifically specified so that the group is bonded directly or via a linking group in the direction toward the central squarylium ring. Such compound (1) is a compound that particularly prominently possesses the characteristics of compound (T) of emitting light in the long wavelength near infrared region and being able to be incorporated into a component at a high concentration.

As an embodiment of the present invention, from the viewpoint of emitting light in the near-infrared long wavelength region and being able to be incorporated into components at a high concentration, it is preferable that, in the general formula (1), _L1 is a group having a structure represented by the above formula (L1), and _L2 is a group having a structure represented by the above formula (L4).

In an embodiment of the present invention, from the viewpoint of emitting light in the long wavelength near infrared region and being able to be incorporated into components at high concentrations, it is preferable that the structure represented by the above general formula (1) is a structure represented by the above general formula (1a), general formula (1b), general formula (1c) or general formula (1d).

In an embodiment of the present invention, from the viewpoint of realizing the effects of the present invention, it is preferable that the luminescent component is a luminescent thin film or luminescent particles.

Furthermore, the luminescent compound of the present invention having a structure represented by the above general formula (1a), general formula (1b), general formula (1c), general formula (1d) or general formula (1e) is a novel compound.

The photoelectric conversion material of the present invention is characterized by containing a compound having a structure represented by the above general formula (T). This results in a photoelectric conversion element with high external quantum efficiency.

The present invention, its components, and the modes and aspects for implementing the present invention will be described in detail below. In this application, the symbol "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

In this specification, a compound having a structure represented by general formula (T) is also referred to as compound (T) as described above. In addition, a chemical structural formula may be indicated by adding an abbreviation of the compound having a structure represented by the chemical structural formula, such as compound (1a)-1. Furthermore, a group having a structure represented by general formula (P) is also referred to as group (P), and a group having a structure represented by formula (L1) is also referred to as group (L1). The same applies to other compounds and groups.

[Outline of the light-emitting member of the present invention]
The light-emitting member of the present invention is characterized by containing a compound (T). In the light-emitting member of the present invention, the compound (T) acts as a near-infrared light-emitting agent. The light-emitting member of the present invention is a member having a predetermined shape, and may contain, in addition to the compound (T), a matrix material for uniformly dispersing the compound (T) in the light-emitting member and forming it into a predetermined shape. In addition to the compound (T), the light-emitting member of the present invention may contain various additives within a range that does not impair the effects of the present invention. The components of the light-emitting member of the present invention will be described in detail below.

<Compound (T)>
The compound (T) is a compound having a structure represented by general formula (T).

一般式（Ｔ）において、
Ａ～Ｌは、それぞれ独立して、芳香族炭化水素環又はヘテロ芳香環を表す。
ｎ１～ｎ６は、それぞれ独立して、０～２の整数を表す。
Ｙａ及びＹｂは、それぞれ独立して、ＯＨ基、ＮＨＣＯＲａ（Ｒａは炭化水素基を表す。）基、ＮＨＳＯ_２Ｒｂ（Ｒｂは炭化水素基を表す。）基、又はＮＨＰＯ（ＯＲｆ）（ＯＲｇ）（Ｒｆ及びＲｇはそれぞれ炭化水素基を表す。）基を表す。
Ｙｃ～Ｙｌは、それぞれ独立して、水素原子又は置換基を表す。
ただし、Ｙａ～Ｙｌのうち少なくとも１つは、炭素数４～１２の直鎖状若しくは分岐状のアルキル基（ａ）、又は下記一般式（Ｐ）で表される構造を有する基（Ｐ）を含む基である。

（一般式（Ｐ）において、※は置換部位を表す。Ｑは単結合又は２価の連結基を表す。ｎは１～９の整数を表す。Ｒ_５１は水素原子又はメチル基を表す。）

In general formula (T),
A to L each independently represent an aromatic hydrocarbon ring or a heteroaromatic ring.
n1 to n6 each independently represent an integer of 0 to 2.
Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group).
Yc to Yl each independently represent a hydrogen atom or a substituent.
However, at least one of Ya to Yl is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the following general formula (P):

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

In general formula (T), A to L each independently represent an aromatic hydrocarbon ring or a heteroaromatic ring. The number of carbon atoms in the aromatic hydrocarbon ring or heteroaromatic ring is preferably 4 to 10. Examples of heteroatoms in the heteroaromatic ring include an oxygen atom, a nitrogen atom, and a sulfur atom. Specific examples of the aromatic hydrocarbon ring or heteroaromatic ring include a benzene ring, a naphthalene ring, a pyridine ring, a thiophene ring, a pyrrole ring, and a furan ring, with a benzene ring and a naphthalene ring being preferred.

In general formula (T), n1 to n6 each independently represent an integer of 0 to 2, preferably 0 or 1. In compound (T), the structure connecting the squarylium ring and the nitrogen atom is preferably a benzene ring, a biphenyl ring, or a naphthalene ring. Specifically, this is as described for compound (1).

In compound (T), at least one of Ya to Yl is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the above general formula (P) (hereinafter also referred to as a substituent (E)). In compound (T), the position substituted with the substituent (E), that is, the position of Ya to Yl, is the position that bonds in the direction toward the central squarylium ring.

In addition, Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group). When Ya and Yb have a substituent (E), Ra, Rb, Rf, or Rg is the substituent (E). However, the substituent (E) in this case is limited to a substituent (E) containing an alkyl group (a).

The substituent (E) may be the alkyl group (a) or the group (P) itself, or may be a group in which the alkyl group (a) or the group (P) is bonded to the main skeleton via a divalent linking group. Examples of the linking group include a phenylene group, -O-, an ester bond (-C(=O)O- or -OC(=O)-), an amide bond (-NHCO-), and combinations thereof. As the linking group, -O- and a phenylene group are preferred, and a 1,4-phenylene group is particularly preferred.

When Yc to Yl are substituents (E), it is preferable that the substituent (E) is an alkyl group (a) which may have -O- as a linking group, or the group (P) itself. When Ra, Rb, Rf, or Rg is a substituent (E), it is preferable that it is an alkyl group (a).

The number of substituents (E) in compound (T) may be 1 or more, and is preferably in the range of 1 to 8, more preferably in the range of 2 to 8, and even more preferably in the range of 2 to 4. The preferred positions of the substituents (E) in compound (T) will be explained in more specific compounds described later.

In the substituent (E), examples of the linear alkyl group (a) having 4 to 12 carbon atoms include n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl. Examples of the branched alkyl group (a) having 4 to 12 carbon atoms include isobutyl, s-butyl, t-butyl, 1-propylbutyl, 1-ethylpentyl, 2,4,4-trimethylpentyl, 2-ethylbutyl, 2,2-dimethylpropyl, 2-ethylhexyl, and 2-butyloctyl.

From the viewpoint of solubility, the alkyl group (a) is preferably a branched alkyl group (a) having 4 to 12 carbon atoms. As the branched alkyl group (a), a group having a structure represented by any of the following formulas (a1) to (a7) is preferable. Here, the group (a1) is a 1-propylbutyl group, the group (a2) is a 1-ethylpentyl group, the group (a3) is a 2,4,4-trimethylpentyl group, the group (a4) is an isobutyl group, the group (a5) is a 2-ethylbutyl group, the group (a6) is a 2-ethylhexyl group, and the group (a7) is a 2-butyloctyl group.

When Ra, Rb, Rf or Rg is a branched alkyl group (a), the alkyl group (a) is preferably a group (a1), a group (a2), a group (a3) or a group (a4). When the branched alkyl group (a) is bonded to any other position, the branched alkyl group (a) is preferably a group (a4), a group (a5), a group (a6) or a group (a7).

When the substituent (E) is a group (P), the number n, which indicates the number of repetitions of the oxyethylene group, may be within the range of 1 to 9. From the viewpoint of ease of production, the number n is preferably 2, 3, 4, or 8. In the group (P), Q is a single bond or a divalent linking group. When Q is a divalent linking group, examples of the linking group include an alkylene group having 1 to 4 carbon atoms, a carbonyl group (-C(=O)-), an arylene group having 6 to 12 carbon atoms, and combinations thereof. Q is preferably a single bond, an alkylene group having 1 to 2 carbon atoms, or a carbonyl group. When the group (P) is bonded to the main skeleton via a linking group, the linking group is preferably a phenylene group, and more preferably a 1,4-phenylene group, as described above.

In compound (T), when they are not substituent (E), Ra, Rb, Rf, Rg, and Yc to Yl each include an atom or group selected from a hydrogen atom, an alkyl group or alkoxy group having 1 to 3 carbon atoms, and an aryl group (however, they do not have either a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms). Examples of the aryl group include a phenyl group, a tolyl group, and a xylyl group.

When not a substituent (E), Ra, Rb, Rf, and Rg are preferably methyl groups. When not a substituent (E), Yc to Yl are preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or phenyl groups.

In A to L of compound (T), the hydrogen atom bonded to the aromatic hydrocarbon ring or heteroaromatic ring at a position other than Ya to Yl may be substituted. A to L of compound (T) may further have a substituent (E) at a position other than Ya to Yl, as long as the effect of the present invention is not impaired. Such a position is, for example, a position other than Ya to Yl that is bonded in the direction toward the central squarylium ring. A substituent other than the substituent (E) may be bonded to such a position, and examples of the substituent in this case include the same substituents as those when Ya to Yl are other than the substituent (E).

In the case where A to L of compound (T) have a substituent at a position other than the above, the substituent is preferably a group that does not have a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms. Specific examples of such a substituent include an alkyl group or alkoxy group having 1 to 3 carbon atoms, and an aryl group (however, the group does not have either a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms).

(Compound (1))
The compound (T) is preferably a compound (1) having a structure represented by the following general formula (1).

In formula (1), _L1 represents a group having a structure represented by formula (L1), (L2) or (L3), _{and L2} represents a group having a structure represented by formula (L4), (L5) or (L6).

In formulas (L1) to (L6), *1 and *4 each represent a site bonded to N in general formula (1). *2 and *3 each represent a site bonded to a carbon of the squarylium ring in general formula (1). R ₁ , R ₅ , R ₂₁ and R ₂₇ each independently represent an OH group, an NHCORa (Ra represents a hydrocarbon group), an NHSO ₂ Rb (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) (Rf and Rg each represent a hydrocarbon group). R ₂ to R ₄ , R ₆ to R ₈ , R ₁₁ to R ₁₈ , R ₂₂ to R ₂₆ and R ₂₈ to R ₃₂ each independently represent a hydrogen atom or a substituent.

In formula (1), Ar ₁ to Ar ₄ each independently represent a group having a structure represented by formula (A), formula (B) or formula (C) below.

In formulae (A) to (C), * indicates a connection site with the N atom. X ₁ to X ₂₇ each independently represent a hydrogen atom or a substituent.

In general formula (1), any of L ₁ , L ₂ and Ar ₁ to Ar ₄ has a linear or branched alkyl group (a) having 4 to 12 carbon atoms or a group (P) having a structure represented by general formula (P) at at least one of the following specified positions:

The predetermined position in _L1 or _L2 is Ra when _R1 , _R5 , _R21 and _R27 are NHCORa groups (excluding group (P)), Rb when _R1 , R5, _R21 and _R27 are _NHSO2Rb groups (excluding group (P)), Rf or Rg when R1, _R5 , _R21 and _R27 are NHPO(ORf)(ORg) groups (excluding group ( _P )), _R2 , _R11 , _{R12 , R6} , _R15 , _R16 , _R26 and _R32 . The predetermined positions in Ar ₁ to Ar ₄ are X ₁ , X ₅ , X ₁₁ , X ₂₁ and X ₂₇ , as well as X ₃₁ and X ₃₅ in the following formula (D).

Furthermore, in general formula (1 ₎ , R ₃ , R ₄ , R ₁₃ , R ₁₄ , R ₂₃ , R ₂₄ , R ₂₅ , R ₇ , R ₈ , R ₁₇ , R ₁₈ , R ₂₉ , R ₃₀ and R ₃₁ in L _{1 or L 2, and X 2 , X 3 , X 4 , X 12 , X 13 , X 14 , X 15 , X 22 , X 23 , X 24 and X 25 in Ar 1 to Ar 4 do not have a linear or branched alkyl group or a (} poly)oxyalkylene group having 4 or more carbon atoms. However, X ₃ , X ₁₃ and X ₂₄ may be a group having a structure represented by the following formula (D).

In formula (D), * indicates a connecting site. X ₃₁ to X ₃₅ each independently represent a hydrogen atom or a substituent. However, at least one of X ₃₁ and X ₃₅ is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group having a group (P) having a structure represented by general formula (P), and X ₃₂ to X ₃₄ do not have a linear or branched alkyl group having 4 or more carbon atoms or a (poly)oxyalkylene group.

In compound (1), "any of L ₁ , L ₂ , and Ar ₁ to Ar ₄ has an alkyl group (a) or a group (P) at at least one of the predetermined positions" means that in compound (1), at least one of the predetermined positions is substituted with a substituent (substituent (E)) containing an alkyl group (a) or a group (P). In compound (1), the predetermined position substituted with a substituent (E) is a position that bonds toward the central squarylium ring.

Specifically, the predetermined position in _L1 or _L2 is Ra when _R1 , _{R5, R21} and _R27 are NHCORa groups (excluding group (P)), Rb when R1, _R5 , _R21 and _R27 are _NHSO2Rb groups (excluding group ( _P )), Rf or Rg when _R1 , _R5 , _R21 and _R27 are NHPO(ORf)(ORg) groups (excluding group ( _P )), _R2 , R11, _R12 , _{R6 , R15} , _R16 , _R26 and _R32 . The predetermined positions in Ar ₁ to Ar ₄ are X 31 and X 35 when X ₁ , X ₅ , X ₁₁ , X ₂₁ and X ₂₇ , and X ₃ , X ₁₃ and X ₂₄ are groups having a structure represented by the above formula ( _{D )} (group (D)).

That is, in the compound (1), in _L1 or _L2 , when _R1 , R5, _R21 and _R27 are NHCORa groups, Ra, when R1, R5, _R21 and R27 are _NHSO2Rb groups, Rf or Rg when NHPO(ORf)(ORg) groups, _R2 , R11, _R12 , _R6 , _R15 , _R16 , _R26 and _R32 , _X1 , _X5 , _X11 , _X21 and _X27 of _Ar1 to _Ar4 , and X31 and _X35 when _X3 , _X13 and _X24 are group (D), at least one of _them is a substituent (E). However, Ra, _Rb , Rf and Rg are limited to the substituent (E) containing an alkyl group (a).

The substituent (E) is the same as the substituent (E) in the case of the above compound (T), including preferred embodiments. When R ₂ , R ₁₁ , R ₁₂ , R ₆ , R ₁₅ , R ₁₆ , R ₂₆ or R ₃₂ is a substituent (E), the substituent (E) is preferably an alkyl group (a) which may have -O- as a linking group or the group (P) itself. When Ra, Rb, Rf or Rg is a substituent (E), it is preferably an alkyl group (a). When _{L 1} or L ₂ has a substituent (E), it is preferable that R ₁ , R ₅ , R ₂₁ or R ₂₇ is NHCORa, and Ra is an alkyl group (a).

When _X1 , _X5 , _X11 , _X21 , and _X27 , and _X3 , _X13 , and _X24 are group (D), and _X31 and _X35 are substituents (E), the substituent (E) may be the alkyl group (a) or group (P) itself, or the alkyl group (a) or group (P) having a linking group. The alkyl group (a) or group (P) itself which may have -O- as a linking group is preferable.

Here, in addition to the above, compound (1) may optionally have a substituent (E) at R ₂₂ and R ₂₈ in L ₁ or L ₂ , and at X ₁₆ , X ₁₇ and X ₂₆ in Ar ₁ to Ar ₄ .

The number of the substituents (E) in the compound (1) is the same as that of the substituents (E) in the compound (T) above. The preferred position of the substituents (E) in the compound (1) will be described in more specific compounds described later.

In the compound (1), when not a substituent (E), Ra, Rb, Rf and Rg include an alkyl group having 1 to 3 carbon atoms, a linear or branched alkyl group having 4 or more carbon atoms, or an aryl group not having a polyoxyalkylene group. R ₂ , R ₁₁ , R ₁₂ , R 6 , R ₁₅ , R ₁₆ , R ₂₂ , R ₂₆ , R ₂₈ , R ₃₂ , X ₁ , X _{5 , X 11 , X 16 , X 17 , X 21 , X 26 , X 27 , X 31 and X 35 include a hydrogen atom , an alkyl group} or alkoxy group having 1 to 3 carbon atoms, a linear or branched alkyl group having 4 or more carbon atoms, or an aryl group not having a polyoxyalkylene group. Examples of the aryl group include a phenyl group, a tolyl group, and a xylyl group.

When not a substituent (E), Ra, Rb, Rf and Rg are preferably methyl groups. When not a substituent (E), R ₂ , R ₁₁ , R ₁₂ , R ₆ , R ₁₅ , R ₁₆ , R ₂₂ , R ₂₆ , R ₂₈ and R ₃₂ are preferably hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, more preferably hydrogen atoms. When not a substituent (E), X ₁ , X ₅ , X ₁₁ , X 16 _, X ₁₇ , X ₂₁ , X ₂₆ , X ₂₇ , X ₃₁ and X ₃₅ are preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or phenyl groups, more preferably hydrogen atoms, methyl groups or phenyl groups.

In the general formula (1 ₎ , R ₃ , R ₄ , R ₁₃ , R ₁₄ , R ₂₃ , R ₂₄ , R ₂₅ , R ₇ , _{R 8} , R ₁₇ , R ₁₈ , R ₂₉ , R ₃₀ and R ₃₁ in L 1 or L 2, X ₂ , X ₃ , X 4 , X ₁₂ , X ₁₃ , X ₁₄ , X ₁₅ , X ₂₂ , X ₂₃ , X ₂₄ and X ₂₅ in Ar ₁ to Ar ₄ , and X ₃₂ to X ₃₄ when X ₃ , X ₁₃ and X ₂₄ are group (D), represent atoms or groups bonded to the main skeleton at positions _other than the above-mentioned specified positions. These do not have a linear or branched alkyl group or polyoxyalkylene group having 4 or more carbon atoms.

Specific examples of R ₃ , R ₄ , R ₁₃ , R ₁₄ , R ₂₃ , R ₂₄ , R ₂₅ , R ₇ , R ₈ , R ₁₇ , R ₁₈ , R ₂₉ , R ₃₀ and R ₃₁ in L ₁ or L ₂ , X ₂ , X ₃ , X 4 , X ₁₂ , X ₁₃ , X ₁₄ , X ₁₅ , X ₂₂ , X ₂₃ , X ₂₄ and X ₂₅ in Ar ₁ to Ar ₄ , and X ₃₂ to X ₃₄ when X _{3 ,} X ₁₃ and X ₂₄ are group (D) include a hydrogen atom, an alkyl group or alkoxy group having 1 to 3 carbon atoms, an aryl group (however, not having a linear or branched alkyl group or polyoxyalkylene group having 4 or more carbon atoms), and the like. Of these, R ₃ , R ₄ , R ₁₃ , R ₁₄ , R ₂₃ , R ₂₄ , R ₂₅ , R ₇ , R ₈ , R ₁₇ , R ₁₈ , R ₂₉ , R ₃₀ and R ₃₁ are preferably hydrogen atoms, and X ₂ , X ₃ , X ₄ , X 12 , X ₁₃ , X ₁₄ , X ₁₅ , X ₂₂ , X ₂₃ , X ₂₄ , X ₂₅ and X ₃₂ to X ₃₄ are preferably hydrogen atoms, methyl groups, or phenyl _groups .

Compound (1) is preferably a compound having a symmetrical skeleton with respect to a central squarylium ring. Specific examples of such compounds include compounds (3) to (11) having structures represented by the following general formulas (3) to (11). The symbols in general formulas (3) to (11) represent the same categories as the symbols in general formula (1), including preferred embodiments.

Compounds (3) to (5) are compounds in which L ₁ is a group (L1) and L ₂ is a group (L4) in compound (1). Compounds (6) to (8) are compounds in which L ₁ is a group (L2) and L ₂ is a group (L5) in compound (1). Compounds (9) to (11) are compounds in which L ₁ is a group (L3) and L ₂ is a group (L6) in compound (1). In the embodiment of the present invention, from the viewpoint of emitting light in the near-infrared long wavelength region and being able to be incorporated in a component at a high concentration, compounds (3) to (5) are preferred, and compound (3) is more preferred.

Among the compounds (3), preferred compounds include compounds (1a) to (1d) having structures represented by the following general formulas (1a) to (1d). Among the compounds (1c) and (1d), the structure of the more preferred compound (1e) is shown in the following general formula (1e). Compounds (1a) to (1e) are novel compounds that have not been described in the literature. From the viewpoint of ease of production, it is preferable that compounds (3) to (11) and compounds (1a) to (1e) not only have a symmetrical skeleton with respect to the central squarylium ring, but also have symmetrical substituents.

Below, compounds (3) to (11) and compounds (1a) to (1e) are described as examples of compound (1), but the present invention is not limited to these compounds.

Compound (3) having a structure represented by general formula (3) is a compound in which L ₁ is a group (L1), L ₂ is a group (L4), and Ar ₁ to Ar ₄ are all groups (A) in compound (1).

In the compound (3), when R ₁ and R ₅ are OH groups (the compound is also referred to as compound (31)), R ₂ , R ₆ , and at least one of X ₁ and X ₅ in each of the four groups (A) are substituents (E). Instead of or in addition to these, X ₃ may be a group (D). In the compound (31), it is preferable that at least one of X ₁ and X ₅ in each of the four groups (A) is a substituent (E). Furthermore, it is preferable that one substituent (E) is present in each of the four groups (A).

That is, in the general formula (3), when the groups (A) corresponding to Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ in the general formula (1) are the groups (A1), (A2), (A3), and (A4), it is preferable that in the compound (31), the substituents (E) are present in each of X ₁ or X ₅ in the group (A1), X ₁ or X ₅ in the group (A2), X ₁ or X ₅ in the group (A3), and X ₁ or X ₅ in the group (A4). In that case, it is preferable that R ₂ , R ₆ , R ₃ , R ₄ , R ₇ , and R ₈ are hydrogen atoms. Of _X1 and _X5 in the groups (A1), (A2), (A3) and (A4), _X1 or _X5 , _X2 , _X3 and _X4 which are not the substituent (E) are preferably a hydrogen atom, a methyl group or a phenyl group. As the substituent (E) in the compound (31), the groups described above can be applied without any particular limitation.

In the compound (31), examples of the compound in which at least one of _X1 and _X5 in the four groups (A) is a substituent (E) include a compound (1a) having a structure represented by the following general formula (1a) and a compound (1c) having a structure represented by the following general formula (1c).

In general formula (1a), each Rc independently represents a hydrogen atom or a substituent, and at least one of the four Rcs is an alkyl group (a) or a group (P) which may have -O- as a linking group. The substituent (E) in compound (1a) is a group having a structure in which the alkyl group (a) or the group (P) is bonded to a 1,4-phenylene group which is a linking group. The substituent (E) may be a group having a 1,4-phenylene group and -O- in that order as linking groups, and in which the alkyl group (a) is bonded to the -O-.

Table I shows examples of compounds in which all four Rc in compound (1a) are the same alkyl group (a), alkyl group (a) having -O- as a linking group, or group (P). Table I lists the compound names and the types of Rc possessed by the compounds. In Table I, only abbreviations are shown for the compound names. Similarly, in the tables showing examples of other compounds shown below, only abbreviations are shown for the compound names.

In Table I, "n-butyl" refers to an n-butyl group, "n-pentyl" refers to an n-pentyl group, "n-hexyl" refers to an n-hexyl group, "n-heptyl" refers to an n-heptyl group, "n-octyl" refers to an n-octyl group, "n-nonyl" refers to an n-nonyl group, "n-decyl" refers to an n-decyl group, "n-undecyl" refers to an n-undecyl group, and "n-dodecyl" refers to an n-dodecyl group. An n-butyl group having -O- as a linking group is represented as "-O-n-butyl". Group (a1) is represented as (a1). Group (P) is represented as (P), and the type of Q, the number of n, and the type of R ₅₁ are shown in parentheses after "(P)", such as (P) (Q = -CH ₂ -, n = 2, R ₅₁ = CH ₃ ). However, when Q is a single bond, the notation of Q is omitted. The same applies to the descriptions in the tables relating to other compounds described later.

In general formula (1c), each Rd independently represents a hydrogen atom or a substituent, and at least one of the four Rds is an alkyl group (a), an alkyl group (a) having -O- as a linking group, or a group (P). Each Xa independently represents an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group, and Xa bonded to the 4th position may be a group (D). In other cases, Xa does not have a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms as a substituent. m represents an integer of 0 to 4. The substituent (E) of compound (1c) is the alkyl group (a) or group (P) itself, or an alkyl group (a) having -O- as a linking group.

In compound (1c), in the four groups (A) bonded to the nitrogen atom, the hydrogen atoms at positions other than the position to which Rd is bonded may be substituted with a substituent Xa. When compound (1c) has a substituent Xa, it is preferable that the substituent Xa is bonded to a carbon atom other than the carbon atom adjacent to the carbon atom bonded to the nitrogen atom. Compound (1c) does not have a substituent Xa, or if it has a substituent Xa, the number of the substituents is preferably 1 or 2, and more preferably 1.

Table II shows examples of compounds (1c) in which all four groups (A) are the same. All Rds in the four groups (A) are the same alkyl group (a) or group (P). Table II shows the compound name, the type of Rd possessed by the compound, and the groups or atoms bonded to the carbon atoms other than the carbon atom to which Rd is bonded in group (A), in order from the group bonded to the carbon atom adjacent to the carbon atom on the opposite side to the nitrogen atom of the carbon atom to which Rd is bonded, as X11, X12, X13, and X14. In Table II, "-O-(a2)" indicates group (a2) to which -O- is bonded as a linking group. In addition, "2,4,6-trimethoxyphenyl" indicates a 2,4,6-trimethoxyphenyl group, "Me" indicates a methyl group, and "Ph" indicates a phenyl group. The same applies to the descriptions in the tables relating to other compounds described below.

In the compound (3), when R ₁ and R ₅ are NHCORa groups (the compound is also referred to as compound (32)), at least one of Ra, R ₂ , R ₆ , and each of X ₁ and X ₅ in the four groups (A) is a substituent (E). Instead of or in addition to these, X ₃ may be a group (D). However, Ra is limited to a substituent (E) containing an alkyl group (a). In the compound (32), it is preferable that at least one of Ra, each of X ₁ and X ₅ in the four groups (A) is a substituent (E). Furthermore, it is preferable that one substituent (E) is present in each of the four groups (A).

That is, in the compound (32), as in the compound (31), it is preferable that the substituent (E) is present in the group (A1) as _X1 or _X5 , in the group (A2) as _X1 or _X5 , in the group (A3) as _X1 or _X5 , and in the group (A4) as _X1 or _X5 . In that case, it is preferable that Ra is an alkyl group (a) or a methyl group. Furthermore, it is preferable that _R2 , _R6 , _R7 , and _R8 are hydrogen atoms. It is preferable that _X1 or _X5 , X2, _X3 , and X4, which are not the substituent (E) among X1 and _X5 in the group ( _A1 ), group (A2), group ( _A3 ), and group (A4 ₎ , are hydrogen atoms, methyl groups, or phenyl groups. As the substituent (E) in the compound (32), each group described above can be applied without any particular limitation.

In compound (32), examples of a compound in which at least one of _X1 and _X5 in the four groups (A) is a substituent (E) include compound (1b) having a structure represented by the following general formula (1b) and compound (1d) having a structure represented by the following general formula (1d).

In the general formula (1b), each Ra independently represents a hydrocarbon group. Each Rc independently represents a hydrogen atom or a substituent. Either of the two Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of the four Rcs represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the general formula (P). In the compound (1b), the groups corresponding to Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ in the general formula (1) are groups (A), and the substituent (E) of the group (A) is a group having a structure in which the alkyl group (a) or the group (P) is bonded to a 1,4-phenylene group which is a linking group. The substituent (E) of the group (A) may be a group having a 1,4-phenylene group and -O- in that order as a linking group, with an alkyl group (a) bonded to the -O-. Ra is preferably the alkyl group (a) or an alkyl group having 1 to 3 carbon atoms.

In compound (1b), examples of compounds in which two Ra are the same alkyl group and all four Rc are the same alkyl group (a), alkyl group (a) having -O- as a linking group, or group (P) are shown in Table III. Table III lists the compound names and the types of Rc and Ra that the compounds have.

In general formula (1d), each Ra independently represents a hydrocarbon group. Each Re independently represents a hydrogen atom or a substituent. Each Xa independently represents an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group, and when Xa is bonded to the 4th position, it may be a group (D). In other cases, Xa does not have a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms as a substituent. m represents an integer of 0 to 4. However, in general formula (1d), any of the Ra's represents an alkyl group (a), or at least one of the four Re's is an alkyl group (a), an alkyl group (a) having -O- as a linking group, or a group (P), or a group (D) is bonded to the 4th position as Xa.

As described above, in compound (1d), in the four groups (A) bonded to the nitrogen atom, the hydrogen atoms at positions other than the position to which Re is bonded may be substituted with a substituent Xa. When compound (1d) has a substituent Xa, it is preferable that the substituent Xa is bonded to a carbon atom other than the carbon atom adjacent to the carbon atom bonded to the nitrogen atom. Compound (1d) does not have a substituent Xa, or if it has a substituent Xa, the number of Xa is preferably 1 or 2, and more preferably 1. In addition, in a group having a benzene ring skeleton that is four groups (A) bonded to a nitrogen atom, when Xa is at the 4th position of the benzene ring, the Xa is preferably a group (D).

In compound (1d), Ra or Re corresponds to the substituent (E). Or, Xa is bonded to the 4th position of the benzene ring having Re, and the Xa is a group (D). In compound (1d), only Ra may be a substituent (E), or only Re may be a substituent (E). The compound (1d) may have a structure in which Ra and Re are not substituents (E), but Xa is bonded to the 4th position of the benzene ring having Re, and the Xa is a group (D). Two or three of these may be a substituent (E) or have a substituent (E).

When Ra is a substituent (E), the substituent (E) is an alkyl group (a). When Ra is not a substituent (E), Ra is preferably an alkyl group having 1 to 3 carbon atoms. When Re is a substituent (E), the substituent (E) is an alkyl group (a), an alkyl group (a) having -O- as a linking group, or the group (P) itself. The substituent (E) that the group (D) has on X ₃₁ or X ₃₅ is preferably an alkyl group (a), an alkyl group (a) having -O- as a linking group, or the group (P) itself. When Re, X ₃₁ and X ₃₅ of the group (D) are not a substituent (E), an alkyl group having 1 to 3 carbon atoms or a phenyl group is preferably used. In the compound (1d), Re is preferably a substituent (E).

Table IV shows examples of compounds (1d) in which the two Ra's and the four groups (A) are all the same. The two Ra's are methyl, ethyl (indicated by "Et" in the table), or alkyl (a). The Re's in the four groups (A) are all the same alkyl (a), group (P), methyl, or phenyl. Table IV shows the compound name, the type of Ra and Re that the compound has, and the groups or atoms that are bonded to carbon atoms other than the carbon atom to which Re is bonded in group (A), in order from the group bonded to the carbon atom next to the carbon atom on the opposite side to the nitrogen atom of the carbon atom to which Re is bonded, as X11, X12, X13, and X14. X12 corresponds to the 4th position in the benzene ring of group (A). "(D)-1" in Table IV shows a group having a structure represented by the following formula.

In compounds (1c) and (1d), it is preferable that the 4-position of the benzene ring of the four groups (A) bonded to the nitrogen atom does not have a substituent. An example of such a compound is compound (1e) having a structure represented by the following general formula (1e).

In general formula (1e), Ya and Yb each independently represent an OH group or an NHCORa group (Ra represents a hydrocarbon group). Each Re each independently represents a hydrogen atom or a substituent. Each Xa each independently represents an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group. However, Xa does not have a linear or branched alkyl group or a (poly)oxyalkylene group having 4 or more carbon atoms as a substituent. m represents an integer of 0 to 3. However, any of the Ra's represents an alkyl group (a), or at least one of the four Re's represents an alkyl group (a), an alkyl group (a) having -O- as a linking group, or a group (P).

The same explanation can be applied to each group in compound (1e) except that the 4-position on the benzene ring of the four groups (A) bonded to the nitrogen atom in each group in compound (1c) and compound (1d) above does not have a substituent.

Specific examples of compounds classified as compound (1e) include compounds (1c)-1 to (1c)-38 and compound (1c)-40 among the compounds shown in Table II above. Furthermore, examples of compounds classified as compound (1d)-1 to (1d)-31, compound (1d)-33, compound (1d)-35, compound (1d)-37, compound (1d)-39, and compound (1d)-41 among the compounds shown in Table IV above.

Compound (4) having a structure represented by general formula (4) is a compound in which L ₁ is a group (L1), L ₂ is a group (L4), and Ar ₁ to Ar ₄ are all groups (B) in compound (1).

In the compound (4), when R ₁ and R ₅ are OH groups, at least one of R ₂ , R ₆ and each X ₁₁ in the four groups (B) is a substituent (E). Alternatively, instead of or in addition to these, X ₁₃ may be a group (D). Note that each X ₁₆ and X ₁₇ can be a substituent (E) as desired. In the following description, in the compound (4) having a structure represented by general formula (4), a compound in which R ₁ and R ₅ in general formula (4) are OH groups is referred to as compound (41).

In the compound (41), it is preferable that at least one of _X11 in each of the four groups (B) is a substituent (E). Furthermore, it is preferable that one substituent (E) is present in each of the four groups (B).

That is, in the general formula (4), the groups (B) corresponding to Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ in the general formula (1) are group (B1), group (B2), group (B3), and group (B4), respectively, and in the compound (41), the substituent (E) is preferably present in X ₁₁ of the group (B1), X ₁₁ of the group (B2), X ₁₁ of the group (B3), and X ₁₁ of the group (B4). In that case, R ₂ , R ₆ , R ₇ , and R ₈ are preferably hydrogen atoms. X ₁₂ , X ₁₃ , X ₁₄ , X 15 , X ₁₆ , and X ₁₇ in the group (B1), group (B2), group (B3), and group (B4 ₎ are preferably hydrogen atoms, methyl groups, or phenyl groups. As the substituent (E) in the compound (41), the groups explained above can be applied without any particular limitation.

In the compound (4), when R ₁ and R ₅ in the general formula (4) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (42). In the compound (42), at least one of Ra, Rb, Rf, Rg, R ₂ , R ₆ , and each X ₁₁ in the four groups (B) is a substituent (E). Alternatively, instead of or in addition to these, X ₁₃ may be a group (D). Note that each X ₁₆ and X ₁₇ can be a substituent (E) arbitrarily. However, Ra, Rb, Rf, and Rg are limited to the substituent (E) containing an alkyl group (a).

In the compound (42), it is preferable that at least one of Ra, Rb, Rf, and Rg, and each _X11 in the four groups (B) is a substituent (E). When the four groups (B) have a substituent (E), it is preferable that one substituent (E) is present in each of the four groups (B).

Examples of Ra, Rb, Rf, and Rg that are not the substituent (E) include an alkyl group having 1 to 3 carbon atoms, a phenyl group, a tolyl group, an aryl group such as a xylyl group, etc. When not the substituent (E), R ₂ and R ₆ , as well as R ₃ , R ₄ , R ₇ , and R ₈ , are preferably hydrogen atoms. In the groups (B1), (B2), (B3), and (B4), X ₁₂ , X ₁₃ , X ₁₄ , X ₁₅ , X ₁₆ , and X ₁₇ are preferably hydrogen atoms, methyl groups, or phenyl groups. As the substituent (E) in the compound (42), the groups described above can be applied without any particular restrictions.

Table V shows an example of compound (4). In the table, "tolyl" refers to the tolyl group.

Compound (5) having a structure represented by general formula (5) is a compound in which L ₁ is a group (L1), L ₂ is a group (L4), and Ar ₁ to Ar ₄ are all groups (C) in compound (1).

In the compound (5), when R ₁ and R ₅ in the general formula (5) are OH groups, the compound is also called compound (51). In the compound (51), at least one of R ₂ , R ₆ , and each of X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E). Alternatively, instead of or in addition to these, X ₂₄ may be a group (D). Note that each X ₂₆ can be a substituent (E) as desired. In the compound (51), it is preferable that at least one of X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E). Furthermore, it is preferable that one substituent (E) is present in each of the four groups (C).

That is, in the general formula (5), when the groups (C) corresponding to Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ in the general formula (1) are group (C1), group (C2), group (C3), and group (C4), in the compound (51), it is preferable that the substituents (E) are present in each of X ₂₁ or X ₂₇ in the group (C1), X ₂₁ or X ₂₇ in the group (C2), X ₂₁ or X ₂₇ in the group (C3), and X ₂₁ or X ₂₇ in the group (C4). In that case, it is preferable that R ₂ and R ₆ , and R ₃ , R ₄ , R ₇ , and R ₈ are hydrogen atoms. Among _X21 and _X27 in the group (C1), group (C2), group (C3) and group (C4), _X21 and _X27 that are not the substituent (E), and _X22 , _X23 , _X24 , _X25 and _X26 are preferably a hydrogen atom, a methyl group or a phenyl group. As the substituent (E) in the compound (51), each group described above can be applied without any particular limitation.

In the compound (5), when R ₁ and R ₅ in the general formula (5) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (52). In the compound (52), at least one of Ra, Rb, Rf, Rg, R ₂ , R ₆ , and each of X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E). Alternatively, instead of or in addition to these, X ₂₄ may be a group (D). Note that each X ₂₆ can be a substituent (E) arbitrarily. However, Ra, Rb, Rf, and Rg are limited to the substituent (E) containing an alkyl group (a).

In the compound (52), it is preferable that at least one of Ra, Rb, Rf, and Rg, and each of _X21 and _X27 in the four groups (C) is a substituent (E). When the four groups (C) have a substituent (E), it is preferable that one substituent (E) is present in each of the four groups (C).

Examples of Ra, Rb, Rf, and Rg that are not the substituents (E) include alkyl groups having 1 to 3 carbon atoms, aryl groups such as phenyl groups, tolyl groups, and xylyl groups. When not the substituents (E), R ₂ and R ₆ , as well as R ₃ , R ₄ , R ₇ , and R ₈ , are preferably hydrogen atoms. Among X ₂₁ and X _{27 in the groups (C1), (C2), (C3), and (C4), X 21 and X 27 that are} not the substituents (E), as well as X ₂₂ , X ₂₃ , X ₂₄ , X ₂₅ , and X ₂₆ , are preferably hydrogen atoms, methyl groups, or phenyl groups. As the substituents (E) in the compound (52), the groups described above can be applied without any particular restrictions.

An example of compound (5) is shown in Table VI.

Compounds (6) to (8) having structures represented by general formulas (6) to (8) are compounds in which L ₁ is a group (L2) and L ₂ is a group (L5) in compound (1). Compound (6) is a compound in which Ar ₁ to Ar ₄ are all group (A), compound (7) is a compound in which Ar ₁ to Ar ₄ are all group (B), and compound (8) is a compound in which Ar ₁ to Ar ₄ are all group (C).

In the compounds (6) to (8), the portions corresponding to Ar ₁ to Ar ₄ in the general formula (1) can be explained with reference to the compounds (3) to (5). The compounds (6) to (8) have in common that L ₁ is a group (L2) and L ₂ is a group (L5). In the compound (6), when R ₁ and R ₅ in the general formula (6) are OH groups, the compound is also called a compound (61). Similarly, in the compound (7), when R ₁ and R ₅ in the general formula (7) are OH groups, the compound is also called a compound (71). In addition, in the compound (8), when R ₁ and R ₅ in the general formula (8) are OH groups, the compound is also called a compound (81).

In compound (61), at least one of R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₁ and X ₅ in the four groups (A) is a substituent (E). In compound (71), at least one of R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₁₁ in the four groups (B) is a substituent (E). In compound (81), at least one of R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E).

Alternatively, instead of or in addition to these, _X3 in compound (61), _X13 in compound (71), and _X24 in compound (81) may each be a group (D). In compound (71), each _X16 and _X17 may be optionally substituted with a substituent (E). In compound (81), each _X26 may be optionally substituted with a substituent (E). In compound (61), compound (71), and compound (81), it is preferable that one substituent (E) is present in each of the four groups (A), group (B), and group (C).

In the compounds (61), (71) and (81), R ₂ , R ₆ , R ₁₁ , R 12 , R ₁₅ and R ₁₆ , and R ₃ , R 4 _, R ₇ , R ₈ , R ₁₃ , R ₁₄ , R ₁₇ and R ₁₈ , which are _not the substituents (E), are preferably hydrogen atoms or methyl groups. In the compound (61), among the X ₁ to X ₅ possessed by the four groups (A), the X ₁ to X ₅ which are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (71), among the X ₁₁ to X ₁₇ possessed by the four groups (B), the X ₁₁ to X ₁₇ which are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (81), among X ₂₁ to X ₂₇ contained in the four groups (C), X ₂₁ to X ₂₇ that are not the substituent (E) or the group (D) are preferably a hydrogen atom, a methyl group, or a phenyl group.

In the case of compound (6), when R ₁ and R ₅ in the general formula (6) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (62). Similarly, in the case of compound (7), when R ₁ and R ₅ in the general formula (7) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (72). In addition, in the case of compound (8), when R ₁ and R ₅ in the general formula (8) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (82).

In compound (62), at least one of Ra, Rb, Rf, Rg, R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₁ and X ₅ in the four groups (A) is a substituent (E). In compound (72), at least one of Ra, Rb, Rf, Rg, R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₁₁ in the four groups (B) is a substituent (E). In compound (82), at least one of Ra, Rb, Rf, Rg, R ₂ , R ₆ , R ₁₁ , R ₁₂ , R ₁₅ , R ₁₆ , and each X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E).

Alternatively, instead of or in addition to these, _X3 in compound (62), _X13 in compound (72), and _X24 in compound (82) may each be a group (D). In compound (72), each _X16 and _X17 may be optionally substituted with a substituent (E). In compound (82), each _X26 may be optionally substituted with a substituent (E). However, Ra, Rb, Rf, and Rg are limited to the substituent (E) containing an alkyl group (a).

In compounds (62), (72) and (82), it is preferable that the substituent (E) is present in each of the four groups (A), (B) and (C).

In the compounds (62), (72) and (82), R ₂ , R ₆ , R ₁₁ , R 12 , R ₁₅ and R ₁₆ , and R ₃ , R 4 _, R ₇ , R ₈ , R ₁₃ , R ₁₄ , R ₁₇ and R ₁₈ , which are _not the substituents (E), are preferably hydrogen atoms. In the compound (62), among the X ₁ to X ₅ possessed by the four groups (A), the X ₁ to X ₅ which are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (72), among the X ₁₁ to X ₁₇ possessed by the four groups (B), the X ₁₁ to X ₁₇ which are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (82), among X ₂₁ to X ₂₇ contained in the four groups (C), X ₂₁ to X ₂₇ that are not the substituent (E) or the group (D) are preferably a hydrogen atom, a methyl group, or a phenyl group.

Specific examples of compound (6), compound (7) and compound (8) are shown in Tables VII, VIII and IX, respectively. In Table IX, "-O-(a4)" represents a group (a4) bonded with -O- as a linking group.

Compounds (9) to (11) having structures represented by general formulas (9) to (11) are compounds in which L ₁ is a group (L3) and L ₂ is a group (L6) in compound (1). Compound (9) is a compound in which Ar ₁ to Ar ₄ are all group (A), compound (10) is a compound in which Ar ₁ to Ar ₄ are all group (B), and compound (11) is a compound in which Ar ₁ to Ar ₄ are all group (C).

In the compounds (9) to (11), the explanations in the compounds (3) to (5) can be applied to the portions corresponding to Ar ₁ to Ar ₄ in the general formula (1). The compounds (9) to (11) have in common that L ₁ is a group (L3) and L ₂ is a group (L6). In the compound (9), when R ₂₁ and R ₂₇ in the general formula (9) are OH groups, the compound is also called a compound (91). Similarly, in the compound (10), when R ₂₁ and R ₂₇ in the general formula (10) are OH groups, the compound is also called a compound (101). In the compound (11), when R ₂₁ and R ₂₇ in the general formula (11) are OH groups, the compound is also called a compound (111).

In compound (91), at least one of R ₂₆ , R ₃₂ , and each of X ₁ and X ₅ in the four groups (A) is a substituent (E). In compound (101), at least one of R ₂₆ , R ₃₂ , and each of X ₁₁ in the four groups (B) is a substituent (E). In compound (111), at least one of R ₂₆ , R ₃₂ , and each of X ₂₁ and X ₂₇ in the four groups (C) is a substituent (E).

Alternatively, instead of or in addition to these, _X3 in compound (91), _X13 in compound (101), and _X24 in compound (111) may each be a group (D). In compound (91), _R22 and _R28 can be optionally substituted with a substituent (E). In compound (101), _R22 , _R28 , each _X16 , and _X17 can be optionally substituted with a substituent (E). In compound (111), _R22 , _R28 , and each _X26 can be optionally substituted with a substituent (E). In compound (91), compound (101), and compound (111), it is preferable that one substituent (E) is present in each of the four groups (A), group (B), and group (C).

In the compound (91), the compound (101) and the compound (111), R ₂₂ to R ₂₆ and R ₂₈ to R ₃₂ that are not the substituents (E) are preferably hydrogen atoms or methyl groups. In the compound (91), among X ₁ to X ₅ that the four groups (A) have, X ₁ to X ₅ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (101), among X ₁₁ to X ₁₇ that the four groups (B) have, X ₁₁ to X ₁₇ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (111), among X ₂₁ to X ₂₇ that the four groups (C) have, X ₂₁ to X ₂₇ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups.

In the case of compound (9), when R ₂₁ and R ₂₇ in the general formula (9) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (92). Similarly, in the case of compound (10), when R ₂₁ and R ₂₇ in the general formula (10) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (102). In addition, in the case of compound (11), when R ₂₁ and R ₂₇ in the general formula (11) are NHCORa group, NHSO ₂ Rb group, or NHPO(ORf)(ORg) group, the compound is also called compound (112).

In compound (92), at least one of Ra, Rb, Rf, Rg, _R22 , _R26 , _R28 , _R32 , and each _X1 and _X5 in the four groups (A) is a substituent (E). In compound (102), at least one of Ra, Rb, Rf, Rg, _R22 , _R26 , _R28 , _R32 , and each _X11 in the four groups (B) is a substituent (E). In compound (112), at least one of Ra, Rb, Rf, Rg, _R22 , _R26 , _R28 , _R32 , and each _X21 and _X27 in the four groups (C) is a substituent (E).

Alternatively, instead of or in addition to these, _X3 in compound (92), _X13 in compound (102), and _X24 in compound (112) may each be a group (D). In compound (92), _R22 and _R28 can be optionally substituted with a substituent (E). In compound (102), _R22 , _R28 , each _X16 , and _X17 can be optionally substituted with a substituent (E). In compound (112), _R22 , _R28 , and each _X26 can be optionally substituted with a substituent (E). However, Ra, Rb, Rf, and Rg are limited to the substituent (E) containing an alkyl group (a).

In compounds (92), (102) and (112), it is preferable that the substituent (E) is present in each of the four groups (A), (B) and (C).

In the compound (92), the compound (102) and the compound (112), R ₂₂ to R ₂₆ and R ₂₈ to R ₃₂ that are not the substituents (E) are preferably hydrogen atoms. In the compound (92), among X ₁ to X ₅ in the four groups (A), X ₁ to X ₅ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (102), among X ₁₁ to X ₁₇ in the four groups (B), X ₁₁ to X ₁₇ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups. In the compound (112), among X ₂₁ to X ₂₇ in the four groups (C), X ₂₁ to X ₂₇ that are not the substituents (E) or the group (D) are preferably hydrogen atoms, methyl groups or phenyl groups.

Specific examples of compound (9), compound (10) and compound (11) are shown in Tables X, XI and XII, respectively.

The above are examples of compound (1). Of compound (1), compounds (1a) to (1d) are preferred as described above. As compound (1a), compound (1a)-1, compound (1a)-12, and compound (1a)-20 are preferred from the viewpoint of further exerting the effects of the present invention.

Similarly, as compound (1b), compound (1b)-14 and compound (1b)-18 are preferred. As compound (1c), compound (1c)-9, compound (1c)-12, compound (1c)-31 and compound (1c)-42 are preferred. As compound (1d), compound (1d)-1, compound (1d)-14, compound (1d)-36, compound (1d)-39 and compound (1d)-40 are preferred.

As compound (4), compound (4)-5, compound (4)-6, compound (4)-9, and compound (4)-10 are preferred. As compound (5), compound (5)-3, compound (5)-4, and compound (5)-9 are preferred.

As the compound (6), the compounds (6)-3, (6)-4 and (6)-8 are preferred. As the compound (7), the compounds (7)-4, (7)-5, (7)-6 and (7)-8 are preferred. As the compound (8), the compounds (8)-3, (8)-4 and (8)-10 are preferred.

As the compound (9), the compounds (9)-4, (9)-6, (9)-7 and (9)-10 are preferred. As the compound (10), the compounds (10)-2, (10)-4, (10)-5 and (10)-8 are preferred. As the compound (11), the compounds (11)-2, (11)-3 and (11)-7 are preferred.

[Synthesis method]
Compound (1) according to the present invention can be synthesized by referring to the methods described in, for example, Chemistry of Materials, Vol. 23, p. 4789 (2011) or The Journal of Physical Chemistry, Vol. 91, p. 5184 (1987), or the methods described in the reference documents described in these documents. As an example, the synthesis examples of exemplary compounds (1a)-1, (1b)-1, (1c)-1, and (1d)-1 are shown below.

<Synthesis of Exemplary Compound (1a)-1>
Compound (1a)-1 can be synthesized, for example, by the following scheme (A). In the following explanation, the amounts of compounds used, the treatment temperature, the time, etc. are examples and can be appropriately adjusted. The same applies to the synthesis of other compounds.

(Step 1)
m-Anisidine (reagent 1-1), 1.5 equivalents of 1-bromo-2-iodobenzene (reagent 1-2), 5% tris(dibenzylideneacetone)dipalladium(0), 10% tris-tert-butylphosphonium tetrafluoroborate, and 3 equivalents of sodium tert-butoxide are refluxed in 30 mL of xylene. This is extracted, concentrated, and then purified by silica gel column chromatography to obtain intermediate 1-1.

(Step 2)
Intermediate 1-1, 1.1 equivalents of 4-butylphenylboronic acid (reagent 1-3), 5% bis(dibenzylideneacetone)palladium(0), 10% 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, and 6 equivalents of potassium phosphate are heated in a 10:1 mixed solvent of 1,2-dimethoxyethane and water. This is extracted, concentrated, and then purified by silica gel chromatography to obtain intermediate 1-2.

(Step 3)
Next, intermediate 1-2 is cooled to 0° C. in methylene chloride, and a 1M solution of boron tribromide in methylene chloride is added dropwise using a dropping funnel and stirred for 1 hour at 0° C. Then, the mixture is returned to room temperature and stirred for 1 hour, after which water is added for extraction, concentration, and purification by silica gel chromatography to obtain intermediate 1-3.

(Step 4)
Finally, the obtained intermediate 1-3 and 3,4-dihydroxy-3-cyclobutene-1,2-dione are heated in a 1:1 mixed solvent of toluene and butanol for 6 hours. After cooling, the green crystals that fall are collected by filtration to obtain compound (1a)-1. The structure of the compound can be confirmed by mass spectrometry (MS) and ^1H -NMR. Figure 1 shows the ^1H -NMR spectrum of compound (1a)-1 (400 MHz, measurement solvent CDCl3).

<Synthesis of exemplary compound (1b)-1>
Compound (1b)-1 can be synthesized, for example, according to the following scheme (B).

(Step 1)
3-Nitroaniline (reagent 2-1), 1-bromo-2-iodobenzene (reagent 2-2), tris(dibenzylideneacetone)dipalladium(0), tris-tert-butylphosphonium tetrafluoroborate, sodium tert-butoxide, and xylene (30 mL) are refluxed, extracted, concentrated, and purified by silica gel column chromatography to obtain intermediate 2-1.

(Step 2)
Intermediate 2-1, 4-butylphenylboronic acid (reagent 2-3), bis(dibenzylideneacetone)palladium(0), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, and potassium phosphate are heated in a 4:1 mixture of 1,2-dimethoxyethane and water. This is extracted, concentrated, and then purified by silica gel chromatography to obtain intermediate 2-2.

(Step 3)
Next, in a 1:1 mixed solvent of ethanol and tetrahydrofuran, intermediate 2-2 is subjected to catalytic reduction with hydrogen after adding Pd-C (10%) catalyst. After 6 hours, it is confirmed that the reaction is complete, and the Pd-C is removed by filtration through Celite. The mixture is concentrated to obtain intermediate 2-3.

(Step 4)
Next, this intermediate 2-3 is reacted with valeryl chloride (reagent 2-4) to obtain intermediate 2-4.

(Step 5)
Finally, the obtained intermediate 2-4 and 3,4-dihydroxy-3-cyclobutene-1,2-dione (reagent 2-5) are heated in a 1:1 toluene-butanol mixed solvent for 6 hours. After cooling, the mixture is extracted, concentrated, and purified by silica gel column chromatography to obtain compound (1b)-1. The structure of the compound can be confirmed by MS and ^1H -NMR.

<Synthesis of exemplary compound (1c)-1>
Compound (1c)-1 can be synthesized, for example, according to the following scheme (C).

(Step 1)
2-Butylaniline (reagent 3-1), 2.1 equivalents of 3-bromoanisole (reagent 3-2), 0.05 equivalents of tris(dibenzylideneacetone)dipalladium(0), 0.15 equivalents of tris-tert-butylphosphonium tetrafluoroborate, and 1.5 equivalents of sodium tert-butoxide are stirred in 20 mL of toluene at 100° C. for 6 hours. This is extracted and concentrated, and then purified by silica gel column chromatography to obtain intermediate 3-1.

(Step 1a)
Separately, 3 equivalents of p-toluenesulfonic acid is dissolved in 50 mL of acetonitrile for the reagent 3-1, cooled to 0°C, and a solution of 2 equivalents of sodium nitrite and 2.5 equivalents of potassium iodide dissolved in 20 mL of water is added dropwise over 30 minutes, and after the dropwise addition, the mixture is stirred at room temperature for 1 hour. This is extracted and purified by silica gel column chromatography to obtain intermediate 3-2.

(Step 2)
Intermediate 3-1 is reacted with 1.3 equivalents of intermediate 3-2, 0.03 equivalents of tris(dibenzylideneacetone)dipalladium(0), 0.1 equivalents of tris-tert-butylphosphonium tetrafluoroborate, 1.5 equivalents of sodium tert-butoxide in 30 mL of xylene at 135° C. for 16 hours. The mixture is extracted and concentrated, and then purified by silica gel column chromatography to obtain intermediate 3-3.

(Step 3)
Intermediate 3-3 is dissolved in 30 mL of dehydrated methylene chloride and cooled to 0° C. Two equivalents of a methylene chloride solution (1 M) of boron tribromide are added dropwise to the solution, which is then stirred at room temperature for 8 hours. The solution is extracted, concentrated, and purified by silica gel column chromatography to obtain intermediate 3-4.

(Step 4)
Finally, the obtained intermediate 3-4 and 0.4 equivalents of 3,4-dihydroxy-3-cyclobutene-1,2-dione (reagent 3-3) are heated in a 1:2 toluene-butanol mixed solvent at 115°C for 16 hours. After cooling, extraction, concentration, and purification by silica gel column chromatography are obtained to obtain compound (1c)-1. The structure of the compound can be confirmed by MS and ^1H -NMR. Figure 2 shows the ^1H -NMR spectrum of compound (1c)-1 (400 MHz, measurement solvent CDCl3).

<Synthesis of exemplary compound (1d)-1>
Compound (1d)-1 can be synthesized, for example, according to the following scheme (D).

(Step 1)
o-Toluidine (reagent 4-1) is reacted with 1 equivalent of 2-bromotoluene (reagent 4-2), 0.03 equivalent of [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride-methylene chloride adduct, 2 equivalents of sodium tert-butoxide, and 200 mL of toluene at 100° C. for 6 hours. This is extracted and concentrated, and then purified by silica gel column chromatography to obtain intermediate 4-1.

(Step 2)
Intermediate 4-1 is reacted with 1.2 equivalents of 3-bromonitrobenzene (reagent 4-3), 0.03 equivalents of tris(dibenzylideneacetone)dipalladium(0), 0.05 equivalents of tris-tert-butylphosphonium tetrafluoroborate, and 2 equivalents of sodium tert-butoxide in 150 mL of xylene at 130° C. for 16 hours. The mixture is extracted and concentrated, and then purified by silica gel column chromatography to obtain intermediate 4-2.

(Step 3)
Next, this intermediate 4-2 is dissolved in 250 mL of ethyl acetate and subjected to catalytic reduction reaction with hydrogen in the presence of 5 g of Pd-C (10%) catalyst at room temperature for 16 hours. The Pd-C is removed by filtration through Celite, and the mixture is concentrated to obtain intermediate 4-3.

(Step 4)
Next, this intermediate 4-3 is dissolved in 150 mL of methylene chloride, 1.5 equivalents of triethylamine is added thereto, and the solution is cooled to 0° C., 1.2 equivalents of valeryl chloride (reagent 4-4) is added thereto, and the mixture is stirred at room temperature for 16 hours. This is extracted, concentrated, and then purified by silica gel column chromatography to obtain intermediate 4-4.

(Step 5)
Finally, the obtained intermediate 4-4 and 3,4-dihydroxy-3-cyclobutene-1,2-dione (reagent 4-5) are heated in a 1:1 toluene-butanol mixed solvent for 6 hours. After cooling, extraction, concentration, and purification by silica gel column chromatography are performed to obtain compound (1d)-1. The structure of the compound can be confirmed by MS and ^1H -NMR. Figure 3 shows the ^1H -NMR spectrum of compound (1d)-1 (400 MHz, measurement solvent CDCl3).

<Optical Properties of Compound (T)>
Compound (T) is a compound that absorbs red light and emits near-infrared fluorescent light. Among compounds (T), compound (1) is preferred in terms of its optical properties. The emission spectrum of compound (T) can be confirmed by the following method.

Compound (T) is adjusted to 10 ⁻⁶ M in a toluene solution, and the emission spectrum of this sample is measured at room temperature (300 K) using a spectrofluorophotometer (Hitachi High-Technos Corporation, F7000).

Compound (T) is a near-infrared light-emitting compound that exhibits fluorescent emission with a maximum emission wavelength (wavelength at which the emission intensity is maximum; also called "emission peak wavelength") exceeding 700 nm in the resulting emission spectrum. The emission peak wavelength of compound (T) is preferably 700 nm or more, and more preferably 710 nm or more.

The absorption peak wavelength is determined by adjusting the compound (T) to 10 ⁻⁶ M in a toluene solution and measuring the absorption spectrum of this sample at room temperature (300 K). A spectrophotometer (Hitachi High-Technos Corporation, F7000) is used to measure the absorption spectrum.

In addition, the luminescence quantum yield of a solution in which compound (T) is dissolved in toluene, etc., and the luminescence quantum yield of a thin film in which compound (T) is dispersed in a matrix material can be measured and used for evaluation, for example, by the following method.

The luminescence quantum yield Φ (%) is expressed as the ratio of the number of absorbed photons to the number of emitted photons. If all excited molecules return to the ground state through fluorescence, the luminescence quantum yield Φ (%) will be 100%, but if non-radiative deactivation occurs, it will not be 100%.

Nonradiative deactivation is a transition that returns to the ground state without emitting fluorescence. In addition to relaxation to the triplet state due to intersystem crossing, there are also internal conversions in which the energy of the electronic state is converted into vibrational energy, etc., and ultimately becomes thermal energy, and energy transfers in which energy is transferred to other molecules.

When the rate constants of the fluorescent transition and the non-radiative transition of a molecule in an excited state are Kf and Knr, respectively, the luminescence quantum yield Φ (%) is expressed by the following formula.
Φ (%) = (Kf/(Kf+Knr))×100

Therefore, in order to improve the luminescence quantum yield, it is necessary to suppress the non-radiative deactivation of molecules in an excited state.

[Light-emitting member]
The light-emitting member of the present invention contains the above-mentioned compound (T), and thus has an emission peak in the long wavelength region of near infrared light and can achieve a high light emission quantum yield. Among the compounds (T), compound (1) is preferred because it can achieve the above characteristics at a higher level. The light-emitting member of the present invention includes a light-emitting thin film, a light-emitting particle, and the like. The light-emitting thin film can also be used as a wavelength conversion film.

The luminescent material of the present invention can be used for bioimaging, for example, as a label in biology and medicine as a dye for a new type of fluorescent probe. In addition, compound (T), which emits fluorescence as excess energy when excited electrons return to the ground state, has wavelength conversion ability due to the difference in absorption and emission energy, and can be used as a color conversion filter in dyes, pigments, optical filters, agricultural films, etc.

Luminescent thin film
The luminescent thin film, which is an embodiment of the luminescent member of the present invention, is characterized by containing a compound (T). The luminescent thin film can be produced by forming a composition obtained by adding a matrix material to compound (T) for film formation stability or the like, or a composition obtained by further adding a solvent thereto, into a thin film.

Examples of matrix materials include (meth)acrylate resins, polyester resins, polyamide resins, polyimide resins, polystyrene resins, polyepoxy resins, polyester resins, amino resins, fluorine resins, phenol resins, polyurethane resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinyl alcohol resins, polyether resins, polyether ketone resins, polyphenylene sulfide resins, polycarbonate resins, and aramid resins, with polystyrene resins, polyethylene resins, polypropylene resins, and polyvinyl chloride resins being preferred. Copolymers of these resins are also preferred.

(Meth)acrylate resins are synthesized by homopolymerizing or copolymerizing various methacrylate or acrylate monomers, and the desired (meth)acrylate resins can be obtained by varying the monomer species and monomer composition ratio. In the present invention, (meth)acrylate monomers can be copolymerized with copolymerizable monomers having unsaturated double bonds other than (meth)acrylate monomers, and poly(meth)acrylate resins can be mixed with multiple other resins.

Examples of monomer components forming the (meth)acrylate resin used in the present invention include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, di(ethylene glycol)ethyl ether (meth)acrylate, ethylene glycol methyl ether (meth)acrylate, isobornyl (meth)acrylate, ethyltrimethylammonium chloride (meth)acrylate, trifluoroethyl (meth)acrylate, octafluoropentyl (meth)acrylate, 2-acetamidomethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-dimethylamino ... ethylaminoethyl (meth)acrylate, 3-trimethoxysilanepropyl (meth)acrylate, benzyl (meth)acrylate, tridecyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate Examples of the acrylates include ethyl (meth)acrylate and glycidyl (meth)acrylate, and preferred are (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, benzyl (meth)acrylate, tridecyl (meth)acrylate, dodecyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

Polystyrene-based resins include homopolymers of styrene monomers, or random copolymers, block copolymers, and graft copolymers obtained by copolymerizing monomers having other unsaturated double bonds that are copolymerizable with styrene monomers. In addition, blends and polymer alloys obtained by blending such polymers with other polymers are also included. Examples of the styrene monomer include styrene, α-methylstyrene, α-ethylstyrene, α-methylstyrene-p-methylstyrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene, and other nuclear alkyl-substituted styrenes, and nuclear halogenated styrenes such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, dichlorostyrene, dibromostyrene, trichlorostyrene, and tribromostyrene, among which styrene and α-methylstyrene are preferred.

Examples of resins used in the present invention by homopolymerizing or copolymerizing these include copolymer resins such as benzyl methacrylate/ethyl acrylate or butyl acrylate, copolymer resins such as methyl methacrylate/2-ethylhexyl methacrylate, copolymer resins such as methyl methacrylate/methacrylic acid/stearyl methacrylate/acetoacetoxyethyl methacrylate, copolymer resins of styrene/acetoacetoxyethyl methacrylate/stearyl methacrylate, copolymer resins of styrene/2-hydroxyethyl methacrylate/stearyl methacrylate, and copolymer resins such as 2-ethylhexyl methacrylate/2-hydroxyethyl methacrylate.

The weight average molecular weight of the above resin is preferably in the range of 1,000 to 1,000,000, more preferably 5,000 to 800,000, and even more preferably 10,000 to 600,000.

In the luminescent thin film, the compound (T) may be used alone or in combination of two or more. The content of the compound (T) in the luminescent thin film is preferably 0.001 parts by mass and 50 parts by mass relative to 100 parts by mass of the matrix material. When the content of the compound (T) is within this range, the luminescent thin film emits light in the long wavelength region of near infrared light and can achieve a high luminescence quantum yield. The more preferred lower limit of the content of the compound (T) is 0.01 parts by mass, the more preferred upper limit is 10 parts by mass, the even more preferred lower limit is 0.05 parts by mass, the even more preferred upper limit is 8 parts by mass, the particularly preferred lower limit is 0.1 parts by mass, and the particularly preferred upper limit is 5 parts by mass. The luminescent thin film can be used appropriately within a thickness range of 0.1 nm to 1 mm.

Luminous Particles
The luminescent particles, which are an embodiment of the luminescent member of the present invention, are characterized by containing a compound (T). The luminescent particles may be luminescent particles having the compound (T) adsorbed on the particle surface, or luminescent particles encapsulating the compound (T).

For example, the compound (T) can be aggregated in a polymer particle dispersion to produce luminescent particles. Alternatively, the luminescent particles may contain the compound (T) by using a swelling polymer in which the polymer particles absorb the solvent and expand in volume when immersed in the solvent.

The polymer particles may be commercially available or may be synthesized by a conventionally known method. The conventionally known method is not particularly limited, but may include dispersion polymerization, suspension polymerization, emulsion polymerization, etc., with emulsion polymerization being preferred. Specifically, the polymer is preferably a thermoplastic resin such as melamine resin or polystyrene resin. The monomers used as the raw material for the polymer may be any of the various monomers listed as the monomers of the matrix material in the above-mentioned luminescent thin film.

In addition, there are no particular limitations on the solvent used when agglomerating compound (T) in the polymer particle dispersion. Any known solvent can be used.

The volume average particle diameter of the polymer particles is preferably within the range of 0.01 to 50 μm, more preferably 0.02 to 1 μm, and even more preferably 0.04 to 0.5 μm.

When the volume average particle diameter is within the above range, the resulting luminescent particles can be used in a variety of applications. Specifically, the volume average particle diameter can be measured using a laser diffraction/scattered light particle size distribution measuring device, LS13320 model.

The weight average molecular weight of the polymer particles is preferably in the range of 1,000 to 1,000,000, more preferably 5,000 to 800,000, and even more preferably 10,000 to 600,000.

The polymer particles contained in the luminescent particles may be of one type or of two or more types, but typically are of one type.

Luminescent particles can also be produced by adding compound (T) to a solution of a resin raw material and then proceeding with a polymerization reaction. For example, when a thermosetting resin such as melamine resin is used as the base resin, a reaction mixture containing the resin raw material (monomer or oligomer or prepolymer, for example, methylol melamine, which is a condensate of melamine and formaldehyde), compound (T), and preferably also a surfactant and a polymerization reaction accelerator (such as an acid) is heated, and a polymerization reaction is allowed to proceed by emulsion polymerization to produce luminescent particles encapsulating compound (T).

In addition, when a thermoplastic resin such as a styrene-based copolymer is used as the base resin, a reaction mixture containing the raw material of the resin, compound (T) (a monomer to which compound (T) has been previously bonded by a covalent bond or the like may be used as the raw material monomer of the resin), and a polymerization initiator (benzoyl peroxide, azobisisobutyronitrile, etc.) can be heated and a polymerization reaction can be caused to proceed by radical polymerization or ionic polymerization, thereby producing luminescent particles encapsulating compound (T).

In addition, for example, luminescent particles can be produced by using silica as a base material and encapsulating compound (T) within it. In this case, a solution in which inorganic semiconductor nanoparticles, compound (T), and a silica precursor such as tetraethoxysilane are dissolved is dropped into a solution in which ethanol and ammonia are dissolved, and the silica precursor is hydrolyzed to produce the luminescent particles.

In the luminescent particles, the compound (T) may be used alone or in combination of two or more kinds. The content of the compound (T) in the luminescent particles is preferably 0.001 parts by mass at the lower limit and 50 parts by mass at the upper limit relative to 100 parts by mass of the polymer particles. When the content of the compound (T) is within this range, the luminescent thin film emits light in the long wavelength region of near infrared light and can achieve a high luminescence quantum yield. The more preferred lower limit of the content of the compound (T) is 0.01 parts by mass, the more preferred upper limit is 10 parts by mass, and the even more preferred lower limit is 0.1 parts by mass.

Wavelength conversion film and infrared emitting surface light source
The above-mentioned light-emitting thin film as a light-emitting member can be used as a wavelength conversion film to prepare an infrared-emitting surface light source. The wavelength conversion film can be applied to an infrared-emitting surface light source because it has a light-emitting thin film containing the compound (T) and emits infrared light (near-infrared light). The wavelength conversion film may be composed of only the above-mentioned light-emitting thin film, or may be a laminated film laminated with other layers.

An infrared-emitting surface light source comprises a surface light source that emits visible light and a wavelength conversion film that converts the visible light, particularly red light, emitted from the surface light source into near-infrared light, and preferably has a maximum emission wavelength in the infrared wavelength range of more than 700 nm.

Figure 4 shows a basic example of the configuration of an infrared-emitting surface light source having a wavelength conversion film with a light-emitting thin film containing compound (T). The infrared-emitting surface light source 1 shown in Figure 4 has a configuration in which a wavelength conversion film 3 that converts the visible light of the red-emitting (R) surface light source 2 to near-infrared light (IR) is disposed on a surface light source 2 that emits visible light, for example, a red-emitting (R) organic EL element.

A surface light source that emits visible light (red) is a light source that has the characteristic of emitting at least red light, and is preferably a surface light source that has a luminance uniformity of 70% or more when uniformly emitting light. A specific surface light source is preferably an organic EL element.

The infrared-emitting surface light source 1 may be configured in such a way that a wavelength conversion film 3 manufactured separately from the surface light source 2 that emits visible light (red) is superimposed on the surface light source 2 that emits visible light (red). Alternatively, the wavelength conversion film 3 may be laminated on the surface light source 2 that emits visible light (red).

The wavelength conversion film 3 may be composed of a single layer of a luminescent thin film containing the compound (T), or may be a laminated structure having a luminescent thin film as shown in Fig. 5. The wavelength conversion film 3 shown in Fig. 5 has a luminescent thin film 5 containing the compound (T), and a gas barrier film 4B is bonded to one surface of the luminescent thin film 5 via an adhesive layer 6, and a gas barrier film 4A is bonded to the other surface.

The thickness of the infrared-emitting surface light source 1 is determined appropriately depending on the application, but is preferably 0.1 to 1000 μm from the standpoint of flexibility and compactness, and more preferably in the range of 1 to 500 μm. Such an infrared-emitting surface light source is suitable for use in biometric measuring devices and biometric authentication devices.

[Photoelectric conversion member]
The photoelectric conversion member of the present invention contains a compound (T). The photoelectric conversion member can be used as a member of a near-infrared photoelectric conversion element.

A near-infrared photoelectric conversion element to which the photoelectric conversion member of the present invention is applied is an element having a photoelectric conversion unit between a pair of opposing electrodes, in which light is incident on the photoelectric conversion unit from above the electrodes. The photoelectric conversion unit generates electrons and holes in response to the incident light, and a signal corresponding to the charge is read out by a semiconductor, indicating the amount of incident light corresponding to the absorption wavelength of the photoelectric conversion unit. A transistor for readout may be connected to the electrode on the side where light is not incident.

In such a near-infrared photoelectric conversion element, the photoelectric conversion material containing compound (T) can be used as a component constituting the photoelectric conversion section, specifically, as the photoelectric conversion layer described below.

The photoelectric conversion section often consists of a photoelectric conversion layer and one or more organic thin film layers other than the photoelectric conversion layer selected from the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, etc. The photoelectric conversion layer may be composed only of compound (T), but may also contain a known infrared absorbing substance in addition to compound (T).

The electrode film used in the near-infrared photoelectric conversion element plays a role of extracting holes from the photoelectric conversion layer and other organic thin film layers and collecting them when the photoelectric conversion layer included in the photoelectric conversion unit described later has hole transport properties or when an organic thin film layer other than the photoelectric conversion layer is a hole transport layer having hole transport properties. Also, when the photoelectric conversion layer included in the photoelectric conversion unit has electron transport properties or when the organic thin film layer is an electron transport layer having electron transport properties, the electrode film plays a role of extracting electrons from the photoelectric conversion layer and other organic thin film layers and ejecting them.

Therefore, there are no particular limitations on the materials that can be used as electrode films as long as they have a certain degree of conductivity, but it is preferable to select a material taking into consideration its adhesion to adjacent photoelectric conversion layers and other organic thin film layers, electron affinity, ionization potential, stability, etc.

Materials that can be used as the electrode film include, for example, conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive substances such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline; and carbon.

These materials may be mixed as necessary, or may be laminated in two or more layers. The conductivity of the material used for the electrode film is not particularly limited as long as it does not unnecessarily interfere with the light reception of the photoelectric conversion element, but it is preferable that it is as high as possible from the viewpoint of the signal strength of the photoelectric conversion element and power consumption. For example, an ITO film having a sheet resistance value of 300 Ω/□ or less functions sufficiently as an electrode film, but since substrates with ITO films having a conductivity of about several Ω/□ are also commercially available, it is desirable to use a substrate having such high conductivity.

The thickness of the ITO film (electrode film) can be selected arbitrarily taking into account electrical conductivity, but is usually about 5 to 500 nm, preferably about 10 to 300 nm. Methods for forming films such as ITO include conventionally known deposition methods, electron beam methods, sputtering methods, chemical reaction methods, and coating methods. The ITO film provided on the substrate may be subjected to UV-ozone treatment, plasma treatment, etc., as necessary.

Examples of materials for the transparent electrode film used on at least one of the sides where light is incident include ITO, IZO, _SnO2 , ATO (antimony-doped tin oxide), ZnO, AZO (aluminum-doped zinc oxide), GZO (gallium-doped zinc oxide), _TiO2 , and FTO (fluorine-doped tin oxide).

The photoelectric conversion section of the photoelectric conversion element includes at least a photoelectric conversion layer and an organic thin film layer other than the photoelectric conversion layer. An organic semiconductor film is generally used for the photoelectric conversion layer constituting the photoelectric conversion section, and the compound (T) of the present invention is contained in this organic semiconductor thin film. The organic semiconductor film may be a single layer or multiple layers. In the case of a single layer, a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film thereof (bulk heterostructure) is used. On the other hand, in the case of multiple layers, it is about 2 to 10 layers, and has a structure in which either a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film thereof (bulk heterostructure) is laminated, and a buffer layer may be inserted between the layers.

In the photoelectric conversion element according to the present invention, the organic thin film layer other than the photoelectric conversion layer constituting the photoelectric conversion section is also used as a layer other than the photoelectric conversion layer, for example, an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, a crystallization prevention layer, or an interlayer contact improvement layer. In particular, by using it as one or more thin film layers selected from the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, and a hole blocking layer, it is preferable to obtain an element that efficiently converts even weak light energy into an electrical signal.

The electron transport layer transports electrons generated in the photoelectric conversion layer to the electrode and blocks the movement of holes from the electrode to which the electrons are transported to the photoelectric conversion layer. The hole transport layer transports generated holes from the photoelectric conversion layer to the electrode and blocks the movement of electrons from the electrode to which the holes are transported to the photoelectric conversion layer. The electron blocking layer prevents the movement of electrons from the electrode to the photoelectric conversion layer, prevents recombination within the photoelectric conversion layer, and reduces dark current. The hole blocking layer prevents the movement of holes from the electrode to the photoelectric conversion layer, prevents recombination within the photoelectric conversion layer, and reduces dark current.

Figure 6 shows a typical element structure of a photoelectric conversion element. In the embodiment of Figure 6, 11 represents an insulating part, 12 represents one electrode film, 13 represents an electron blocking layer, 14 represents a photoelectric conversion layer, 15 represents a hole blocking layer, 16 represents the other electrode, and 17 represents an insulating substrate or another organic photoelectric conversion element. Although a readout transistor is not shown in the figure, it is sufficient that it is connected to the electrode 12 or 16, and further, if the photoelectric conversion layer 14 is transparent, it may be formed on the outside of the electrode on the side opposite to the side where light is incident. Light may be incident on the organic photoelectric conversion element from either the top or bottom, as long as the components other than the photoelectric conversion layer 14 do not excessively inhibit the incidence of light of the main absorption wavelength of the photoelectric conversion layer.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

Example 1
In the compound (1), the compounds classified into compound (3), specifically, compounds (1a) to (1d) and compounds (4) to (11) having the structures shown below were prepared.

Compound (1a)-1, compound (1a)-12, and compound (1a)-20, which are classified as compound (1a), were produced according to the above scheme (A), and their structures were confirmed by MS and ¹ H-NMR.

Compound (1b)-14, which is classified as compound (1b), was produced according to the above scheme (B), and its structure was confirmed by MS and ¹ H-NMR.

Compound (1c)-9, compound (1c)-12, and compound (1c)-31, which are classified as compound (1c), were produced according to the above scheme (C), and their structures were confirmed by MS and ¹ H-NMR.

Compound (1d)-1, compound (1d)-14, compound (1d)-36, compound (1d)-39 and compound (1d)-40, which are classified as compound (1d), were produced according to the above scheme (D), and their structures were confirmed by MS and ^1H -NMR.

Regarding compound (4), compounds (4)-5, (4)-6, (4)-9 and (4)-10 were produced according to the above schemes (A) to (D), and their structures were confirmed by MS and ^1H -NMR.

Regarding compound (5), compounds (5)-3, (5)-4 and (5)-9 were produced according to the methods of the above schemes (A) to (D), and their structures were confirmed by MS and ¹ H-NMR.

Regarding compound (6), compounds (6)-3, (6)-4 and (6)-8 were produced according to the methods of the above schemes (A) to (D), and their structures were confirmed by MS and ¹ H-NMR.

Regarding compound (7), compounds (7)-4, (7)-5, (7)-6 and (7)-8 were produced according to the above schemes (A) to (D), and their structures were confirmed by MS and ^1H -NMR.

Regarding compound (8), compounds (8)-3, (8)-4 and (8)-10 were produced according to the methods of the above schemes (A) to (D), and their structures were confirmed by MS and ¹ H-NMR.

Regarding compound (9), compounds (9)-4, (9)-6, (9)-7 and (9)-10 were produced according to the above schemes (A) to (D), and their structures were confirmed by MS and ^1H -NMR.

Regarding compound (10), compounds (10)-2, (10)-4, (10)-5 and (10)-8 were produced according to the above schemes (A) to (D), and their structures were confirmed by MS and ¹ H-NMR.

Regarding compound (11), compounds (11)-2, (11)-3 and (11)-7 were produced according to the methods of the above schemes (A) to (D), and their structures were confirmed by MS and ¹ H-NMR.

The obtained compounds were adjusted to 10 ^-6 M in a toluene solution, and the fluorescence spectrum of the sample was measured at room temperature (300K). A spectrofluorophotometer (Hitachi High-Technos Corporation, F7000) was used to measure the emission spectrum. In addition, an absorption spectrum was measured using a sample prepared in the same manner. A spectrophotometer (Hitachi High-Technos Corporation, F7000) was used to measure the absorption spectrum. For each of the compounds obtained above, an emission peak was observed in the range of 700 to 900 nm.

Example 2
Among the compounds obtained in Example 1, the compounds shown in Table XIII below, and comparative compound R-1 (a compound described in WO 2018/008721) and comparative compound R-2 (a compound described in Chem. Mater, 23, 4789, 2011) whose structures are shown below were evaluated for luminescence quantum yield in solution and in a thin film state by the following methods.

(1) Evaluation of luminescence quantum yield in solution Each of the above compounds was adjusted to 10 ⁻⁶ M in a toluene solution, and the absolute PL (luminescence) quantum yield of this sample solution (hereinafter referred to as "PLQY solution") was measured at room temperature (300 K) using an absolute PL quantum yield measurement device (manufactured by Hamamatsu Photonics KK: C11347).

(2) Evaluation of luminescence quantum yield in thin film A matrix material, polystyrene (manufactured by ACROS ORGANICS, weight average molecular weight Mw = 260,000) and a comparative compound R-1 were added to toluene to a concentration of 10 ⁻² M, and these were placed in an eggplant flask and heated to 80°C with stirring to fully dissolve.

Using the obtained solution, a thin film was formed on a PET (polyethylene terephthalate) film using an applicator, and then the film was dried at room temperature for 10 minutes, heated and dried at 80°C for 10 minutes, and peeled off from the PET film to prepare a luminescent thin film (comparative example) containing compound R-1. In addition, compound R-1 was replaced with comparative compound R-2 to prepare a luminescent thin film (comparative example) containing compound R-2. Furthermore, luminescent thin films of the present invention were prepared in the same manner except that compound R-1 was replaced with each compound according to the present invention shown in Table XIII. The absolute PL (luminescence) quantum yields (hereinafter referred to as "PLQY films") of these samples were measured at room temperature (300K). The absolute PL (luminescence) quantum yields were measured using an absolute PL quantum yield measurement device (manufactured by Hamamatsu Photonics KK: C11347).

The absolute PL (luminescence) quantum yield of the corresponding luminescent thin film when the absolute PL (luminescence) quantum yield of the luminescent thin film in a toluene solution is taken as 1.00 is shown in Table XIII below as a relative value of the luminescence quantum yield, i.e., PLQY film/PLQY solution.

As can be seen from Table XIII, the luminescent thin films using comparative compound R-1 and compound R-2 maintained luminescence quantum yields of 0.19 and 0.13, respectively, from the solution state, whereas the luminescent thin films using each compound according to the present invention maintained a luminescence quantum yield of 0.50 or more, the same as in the solution state, and concentration quenching was significantly suppressed. Furthermore, the luminescent thin films using each compound according to the present invention had a luminescence quantum yield at a level suitable for practical use.

Example 3
The luminescence quantum yields in solution and in luminescent particles were measured for the compounds shown in Table XIV below among the compounds obtained in Example 1 above, and for the comparative compounds R-1 and R-2.

(1) Evaluation of luminescence quantum yield in solution Each of the above compounds was adjusted to 10 ⁻⁶ M in a toluene solution, and the absolute PL (luminescence) quantum yield of this sample solution (hereinafter referred to as "PLQY solution") was measured at room temperature (300 K) using an absolute PL quantum yield measurement device (manufactured by Hamamatsu Photonics KK: C11347).

(2) Preparation of luminescent particles and evaluation of luminescence quantum yield To 96 μL of polystyrene (PS) particle dispersion (solid content 5.2 mass%, volume average particle size of polystyrene particles 0.12 μm, dispersion medium: water), 100 μL of water, 50 μL of a 2% aqueous solution of a nonionic surfactant (Kolliphor P407: manufactured by Sigma-Aldrich), and 100 μL of a 0.01 mmol/L THF solution of each of the above compounds were added to prepare a mixture of polystyrene particles and each compound. The mixture was stirred at 25 ° C. for 2 minutes to prepare polystyrene particles containing each compound.

The obtained polystyrene particle dispersion was used to settle the particles using a centrifugal purification method, and after removing the supernatant, pure water was added to redisperse the particles. This operation (centrifugal purification and redispersion) was repeated four times to obtain luminescent particle dispersions 1 to 15 containing each compound.

The absolute PL (luminescence) quantum yield of the luminescent particle dispersions 1 to 15 obtained above was measured using an absolute PL quantum yield measurement device (C11347-01 manufactured by Hamamatsu Photonics). The absolute PL (luminescence) quantum yield of the corresponding luminescent particle dispersion when the absolute PL (luminescence) quantum yield of the luminescent thin film in a toluene solution is set to 1.00 is shown in Table XIV below as a relative value of the luminescence quantum yield, i.e., PLQY particles/PLQY solution.

From Table XIV, it can be seen that the luminescent particles using comparative compound R-1 and the luminescent particles using compound R-2 maintained luminescence quantum yields of 0.30 and 0.20, respectively, from the solution state, whereas the luminescent particles using each compound according to the present invention maintained a luminescence quantum yield of 0.50 or more, the same as in the solution state, and concentration quenching was significantly suppressed. Furthermore, the luminescent particles using each compound according to the present invention had a luminescence quantum yield at a level suitable for practical use.

Example 4
A wavelength converting film having a luminescent thin film containing compound (1a)-1 as the compound of the present invention was prepared according to the following method, and an infrared-emitting surface light source was prepared using the wavelength converting film. The prepared wavelength converting film was wavelength converting film 3 having the configuration shown in Figure 5, and the infrared-emitting surface light source was infrared-emitting surface light source 1 having the configuration shown in Figure 4.

(Fabrication of wavelength conversion film 3)
A matrix material, polystyrene (manufactured by ACROS ORGANICS, weight average molecular weight Mw=260,000) and compound (1a)-1 were added to a solvent, toluene, in a mass ratio of 99:1, and the mixture was placed in an eggplant flask and heated to 80° C. with stirring to dissolve thoroughly.

Next, the mixed solution obtained was applied with an applicator onto a gas barrier film 4A having an inorganic gas barrier layer 4A made of _SiOx formed on the entire surface of one side of a polyethylene naphthalate film (manufactured by Teijin DuPont) to a thickness of 500 nm using an atmospheric pressure plasma discharge treatment apparatus having the configuration described in JP-A-2004-68143. After drying at room temperature for 10 minutes, it was further heated and dried at 80° C. for 10 minutes to form a light-emitting thin film 5.

Then, a gas barrier film 4B with a sealing adhesive was prepared and laminated to the surface of the luminescent thin film 5 opposite to the gas barrier film 4A side, and sealing was performed using a vacuum laminator under heating conditions of 90°C. Then, a heat treatment was performed at 110°C for 30 minutes to harden the adhesive and form an adhesive layer 6, thereby producing a wavelength conversion film 3. Although not shown, the wavelength conversion film 3 is configured to include the polyethylene naphthalate film used as the base material.

(Preparation of infrared emitting surface light source)
An infrared-emitting surface light source 1 having the configuration shown in Fig. 4 was produced by closely contacting the light-emitting surface of an organic EL element, which is a surface light source 2 emitting red light (R), with a wavelength conversion film 3. It was confirmed that by making the surface light source emitting red light (R) emit light, the red light of the surface light source emitting red light (R) was converted into near-infrared light.

Example 5
In this example, a photoelectric conversion element having a photoelectric conversion layer containing the compound (1d)-39 obtained above as the compound of the present invention was prepared as follows, and its performance was evaluated.

A 150 nm thick indium tin oxide (ITO) transparent conductive film was deposited on a glass substrate and patterned to a width of 2 mm using standard photolithography techniques and hydrochloric acid etching to form a transparent electrode. The patterned transparent electrode was then ultrasonically cleaned with a surfactant and ultrapure water, then ultrasonically cleaned with ultrapure water, then dried with nitrogen blowing, and finally cleaned with ultraviolet light and ozone.

On this transparent substrate, a 1 mg/mL chloroform solution of compound (1d)-39 was spin-coated to a film thickness of 60 nm, and then heated and dried at 140° C. in the air for 10 minutes. After this, the substrate was brought into a glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 140° C. for 10 minutes under a nitrogen atmosphere. Next, the substrate on which the organic layer was formed was placed in a vacuum deposition apparatus. The element was set so that a 2 mm wide shadow mask was perpendicular to the transparent electrode, and the pressure inside the vacuum deposition apparatus was reduced to 10 ⁻³ Pa or less, after which fullerene C60 was deposited to 40 nm, bathocuproine to 10 nm, and Al to 100 nm. Finally, heating was performed at 120° C. for 30 minutes to obtain a photoelectric conversion element 1 according to the present invention. The deposition rate was 2 nm/sec in each case, and the size was 2 mm square.

The obtained photoelectric conversion element 1 was sealed using an aluminum cap and a UV curing resin (UV RESIN XNR5570-B1, manufactured by Nagase ChemteX Corporation) under a nitrogen atmosphere. When the photoelectric conversion element 1 produced above was irradiated with light of an intensity of 100 mW/ ^cm2 from a solar simulator (AM1.5G filter), an electrical signal was confirmed, and it was confirmed that the element functioned sufficiently as a photoelectric conversion element.

In the above, compound (1d)-39 was replaced with compound (4)-6, compound (5)-4, compound (6)-8, compound (7)-6, compound (8)-4, compound (9)-10, compound (10)-4, and compound (11)-2, and photoelectric conversion elements were similarly prepared and evaluated. As a result, an electrical signal was confirmed in each of these elements, and it was confirmed that they functioned sufficiently as photoelectric conversion elements.

According to the present invention, it is possible to provide a light-emitting component that can achieve a high light emission quantum yield in the long near-infrared wavelength region, which contains a light-emitting compound that can emit light in the long near-infrared wavelength region and can be incorporated into components at a high concentration. It is also possible to provide a light-emitting compound that can emit light in the long near-infrared wavelength region and can be incorporated into components at a high concentration. Furthermore, it is possible to provide a photoelectric conversion component that can obtain a high external quantum efficiency by using a light-emitting compound that can emit light in the long near-infrared wavelength region and can be incorporated into components at a high concentration.

REFERENCE SIGNS LIST 1 Infrared emitting surface light source 2 Surface light source emitting visible light 3 Wavelength conversion film 4A, 4B Gas barrier film 5 Luminescent thin film 6 Adhesive layer IR Near infrared light R Red light emission 11 Insulating portion 12 Upper electrode 13 Electron blocking layer 14 Photoelectric conversion layer 15 Hole blocking layer 16 Lower electrode 17 Insulating substrate or other photoelectric conversion element

Claims (9)

A light-emitting member comprising a compound having a structure represented by the following general formula (T2):

[In the general formula (T2),
A to L each independently represent an aromatic hydrocarbon ring.
Each of n1 to n6 independently represents an integer of 0 or 1.
Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group).
Yc to Yl each independently represent a hydrogen atom or a substituent.
However, at least one of Ya and Yb is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the following general formula (P):

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.) The light-emitting member according to claim 1, wherein in the general formula (T2), at least one of Ye to Yl is a linear or branched alkyl group having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the general formula (P). A light emitting member comprising a compound having a structure represented by the following general formula (1b):

(In general formula (1b), each Ra independently represents a hydrocarbon group. Each Rc independently represents a hydrogen atom or a substituent. Either of two Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Rc's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by general formula (P).) A light emitting member comprising a compound having a structure represented by the following general formula (1d):

(In general formula (1d), each Ra independently represents a hydrocarbon group. Each Re independently represents a hydrogen atom or a substituent. Each Xa independently represents an alkyl group or an alkoxy group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group, and Xa bonded to the 4th position may be a group having a structure represented by the following formula (D). m represents an integer of 0 to 4. However, in general formula (1d), either of two Ra represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Re represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the above general formula (P), or a group having a structure represented by the following formula (D) is bonded to the 4th position as Xa.)

(In formula (D), * denotes a connecting site. X ₃₁ to X ₃₅ each independently represent a hydrogen atom or a substituent. However, at least one of X ₃₁ and X ₃₅ is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group having a group (P) having a structure represented by the following general formula (P), and X ₃₂ to X ₃₄ do not have a linear or branched alkyl group having 4 or more carbon atoms or a (poly)oxyalkylene group.)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.) The light-emitting member according to any one of claims 1 to 4, wherein the light-emitting member is a light-emitting thin film. The light-emitting member according to any one of claims 1 to 4, wherein the light-emitting member is a light-emitting particle. A light-emitting compound having a structure represented by the following general formula (1a):

(In general formula (1a), each Rc independently represents a hydrogen atom or a substituent, and at least one of the four Rc represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the following general formula (P).)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.) A light-emitting compound having a structure represented by the following general formula (1b):

(In general formula (1b), each Ra independently represents a hydrocarbon group. Each Rc independently represents a hydrogen atom or a substituent. Either of two Ra's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or at least one of four Rc's represents a linear or branched alkyl group (a) having 4 to 12 carbon atoms which may have -O- as a linking group, or a group (P) having a structure represented by the following general formula (P).)

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.) A photoelectric conversion member comprising a compound having a structure represented by the following general formula (T):

[In the general formula (T),
A to L each independently represent an aromatic hydrocarbon ring or a heteroaromatic ring.
n1 to n6 each independently represent an integer of 0 to 2.
Ya and Yb each independently represent an OH group, an NHCORa group (Ra represents a hydrocarbon group), an _NHSO2Rb group (Rb represents a hydrocarbon group), or an NHPO(ORf)(ORg) group (Rf and Rg each represent a hydrocarbon group).
Yc to Yl each independently represent a hydrogen atom or a substituent.
However, at least one of Ya to Yl is a linear or branched alkyl group (a) having 4 to 12 carbon atoms, or a group containing a group (P) having a structure represented by the following general formula (P):

(In formula (P), * represents a substitution site. Q represents a single bond or a divalent linking group. n represents an integer of 1 to 9. R ₅₁ represents a hydrogen atom or a methyl group.)

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