JP6876320B2 - Method for producing higher-order acene derivatives - Google Patents

Description

The present invention relates to higher acene derivatives and methods for producing them.

It is said that the high performance of electronic devices based on miniaturization, which has been achieved according to Moore's Law, will end within the next 10 years due to its physical limitations. Therefore, it is desired to emerge an innovative new material that breaks the limits of existing silicon materials. Among them, graphene nanoribbon (GNR) is attracting attention because it exhibits superior physical properties to existing silicon semiconductors.

Examples of the method for producing GNR include a method of forming by electron beam lithography using a negative resist (hydrosilsesquioxane) (Non-Patent Document 1 and the like), and a method of chemically incising carbon nanotubes (for example, Patent Document 1). ), A method of forming graphite flakes dissolved in an organic solvent by a sonochemical method (Non-Patent Document 2 and the like) and the like have been reported.

Recently, anthracene dimers have been synthesized and deposited on a gold (Au) or silver (Ag) metal substrate having a flat (111) crystal plane at the atomic level under ultra-high vacuum, and a radical reaction by heating the substrate. (Non-Patent Document 3, etc., hereinafter, this method is referred to as a sublimation method) is disclosed.

Japanese Unexamined Patent Publication No. 2012-158514 Japanese Unexamined Patent Publication No. 2014-218386

M. Y. Han et al., Phys. Rev. Lett., 98 (2007), 206805 X. Li et al., Science, 319 (2008), 1229 J. Cai et al., Nature, 466 (2010), 470 Chen Y. et al., ACS Nano, 7 (2013), 6123 Zhang, H. et al., J. Am. Chem. Soc., 137 (2015), 4022 Abdurakhmanova, N. et al., Carbon, 77 (2014), 1187

GNR is roughly classified into an armchair type and a zigzag type according to the structure of its edge (side edge), and it is known that the former has a semiconductor property and the latter has a metallic property. Therefore, it is expected that an armchair type GNR will be used as a semiconductor material such as a transistor. When used as a semiconductor material, it is necessary to have an energy bandgap of an appropriate size, but it is known that in an armchair type GNR, the size of the bandgap decreases as the width of the GNR (ribbon width) increases. (Patent Document 2 etc.). In the sublimation method using anthracene dimer as a precursor (Non-Patent Document 3, Non-Patent Document 4, etc.), a GNR having a uniform ribbon width can be produced, but a GNR having a ribbon width of 1 nm or more can be produced. Therefore, it is not possible to obtain a sufficient bandgap size as a semiconductor material. At present, in order to produce a wide GNR, it is necessary to use precursors having different molecular structures (Non-Patent Document 5), and it is necessary to rethink the molecular design for each precursor.
On the other hand, a sublimation method using oligophenylene or the like as a precursor has also been reported (Non-Patent Document 6), but the ribbon width is clean enough to obtain stable quality as a semiconductor device (that is, the ribbon width is uniquely determined). There is a problem that it is not possible to obtain a complete GNR.

An object of the present invention is to easily produce a GNR having a uniform ribbon width in which the ribbon width is uniquely determined, and to provide a compound which can be a material compound of such a GNR.

The present inventor considers that if higher-order acenes can be correctly arranged side by side in an organic solvent, it is possible to easily produce a GNR having a uniform ribbon width in which the ribbon width is uniquely determined. As a result of searching for a higher-order acene derivative having such properties from among the acene derivatives, it was found that the higher-order acene derivative in which an odd number of benzene rings are linearly condensed is useful as a material compound for the above GNR. Find out and complete the present invention.

That is, in the present invention, the 1st and 4th positions of the central benzene ring, which is one benzene ring in the center of the higher-order acene in which three or more odd benzene rings are linearly condensed, are halogens, respectively. Substituted with (fluorine group, chlorine group, bromo group, iodine group),
It is a higher-order acene derivative in which a diketone is crosslinked between the 1-position and the 4-position of each one benzene ring located symmetrically on both sides of the central benzene ring.

In the above-mentioned higher-order acene derivative, the 1st and 4th positions substituted with halogen refer to the positions in the central benzene ring and do not indicate the positions in the whole higher-order acene. That is, when the higher-order acene is anthracene, the 1st and 4th positions of the central benzene ring mean the 5th and 10th positions of anthracene. The same applies to the 1st and 4th positions where the diketone is crosslinked.

In order to obtain a certain wide GNR, it is conceivable to prepare a higher-order acene having the same width as a precursor by a sublimation method, but the higher-order acene generally has low solubility in an organic solvent and is also low in solubility. , It is not easy to handle because it is unstable.

On the other hand, the higher-order acene derivative according to the present invention adds two halogens to one benzene ring (central benzene ring) constituting the higher-order acene, and is symmetrical on both sides of the central benzene ring. Since it is composed of a higher-order acene derivative in which a diketone is crosslinked to each of the benzene rings at various positions, even the higher-order acene derivative is soluble in an organic solvent. In addition, it is easily converted into higher-order acene by irradiating it with light. As a result, it becomes easy to handle when producing GNR by the sublimation method, and it becomes possible to produce GNR in which the ribbon width is uniquely determined. In particular, since the higher-order acene derivative according to the present invention is soluble in organic solvents even in higher-order acenes of heptacene or higher, a wide GNR (width of 7 or more benzene rings) can be easily prepared. .. In addition, higher-order acene derivatives for producing GNRs of various widths can be produced by a unified method.

GNR can be obtained from the higher-order acene derivative according to the present invention by various steps. For example, in the case of a higher-order acene (heptacene) derivative having 7 benzene rings, the GNR is obtained by the step shown in FIG. Is obtained. That is,
a) A higher-order acene derivative is deposited on an Au (111) substrate and debromineed to form a polymer chain (Fig. 1 (a)).
b) Irradiate with light having a wavelength of 450 nm (450 ± 20 nm) to remove the diketone from the polymer chain (Fig. 1 (b)).
c) Dehydrogenate by heating at a temperature of 400 ° C (400 ± 20 ° C) (Fig. 1 (c)).

In the higher-order acene derivative according to the present invention, two halogens are bonded to the central benzene ring, and diketones are crosslinked to the two benzene rings at symmetrical positions on both sides of the central benzene ring. Therefore, it is possible to obtain a polymer chain in which higher-order acene derivatives are correctly arranged side by side. Then, after producing such a polymer chain, the diketone can be easily removed only by irradiating with light, so that a GNR in which the ribbon width is uniquely determined by the subsequent dehydrogenation can be produced.

As a method for producing the higher-order acene derivative according to the present invention, the following method is possible.
a) Dimethyl acetylenedicarboxylate (DMAD) is crosslinked and added to a higher-order acene derivative having a quinone in the central ring by the Diels-Alder reaction.
b) Remove the ester group at the crosslinked part by decarboxylation reaction.
c) Oxygen of quinone is removed by reduction reaction, and halogen is added to the isotope.
d) Oxygen is added to the crosslinked portion by an oxidation reaction to form a diketone.

また、以下の式(２)は、上記高次アセン誘導体のトランス形態の構造を示す。

Specifically, when the higher acene is heptacene and the halogen is bromine (bromo group), one embodiment of the higher acene derivative according to the present invention is [7,16-dibromo-5,9,14. , 18-Tetrahydro-5,18: 9,14-Bisetanoheptacene-19,20,21,22-Tetraketone]. The structure of this higher-order acene derivative is shown in the following formula (1).

Further, the following formula (2) shows the structure of the trans form of the higher-order acene derivative.

Further, the method for producing the higher-order acene derivative is as follows, for example.
a) Dimethyl acetylenedicarboxylate (DMAD) is crosslinked and added to 7,16-heptasenquinone by the Diels-Alder reaction.
b) Remove the ester group at the crosslinked part by decarboxylation reaction.
c) The oxygen of the quinone is removed by the reduction reaction, and a bromo group is added to the isotope.
d) Oxygen was added to the crosslinked part by the oxidation reaction, and 7,16-dibromo-5,9,14,18-tetrahydro-5,18: 9,14-bisethanoheptacene-19,20,21,22- Form tetraketone.

The higher-order acene derivative according to the present invention is basically soluble in an organic solvent, and in particular, even a derivative of a higher-order acene higher than heptacene is soluble in an organic solvent. In addition, it is easily converted into higher-order acene by irradiating it with light. These make it easy to handle when making graphene nanoribbons (GNR) by the sublimation method, and the wide (width of 7 or more benzene rings), the ribbon width is uniquely determined, and the ribbon width is uniform and clean. Can be produced. In addition, higher-order acene derivatives that can be used to produce GNRs of various widths can be produced by a unified method.

FIG. 3 is a manufacturing process diagram of GNR using the higher-order acene derivative according to the present invention. FIG. 6 is a process diagram for synthesizing a higher-order acene derivative according to an embodiment of the present invention.

Hereinafter, specific examples of the higher-order acene derivative and the method for producing the same according to the present invention will be described in detail with reference to the drawings. As the reagents and solvents used for the synthesis in the examples shown below, commercially available products were used as they were, or those purified by distillation in the presence of a desiccant were used. NMR was measured using JNM-ECX400P, JNM-ECX500 and JNM-ECA600 manufactured by JEOL Ltd., and tetramethylsilane (TMS) was used as an internal standard.

In this example, a higher-order acene derivative represented by the symbol 1 in FIG. 2 was produced.

[Formation of compound 3 = process (i)]
7,16-Heptasenquinone (1.0 g, 2.45 mmol) and dimethyl acetylenedicarboxylate (8.4 ml) were suspended in xylene (240 ml), and the mixture was heated and stirred in an autoclave at 170 ° C. for 3 days. After completion of the reaction, the reaction solvent was distilled off under reduced pressure, the obtained residue was purified by silica column chromatography fluffy (ethyl acetate: hexane = 1: 1, Rf = 0.43), and further recrystallized using methanol. , The desired product was isolated in a yield of 43% (730 mg, 1.05 mmol).
The results of structural analysis of the target product by ¹ H nuclear magnetic resonance spectroscopy ( ¹ H NMR) are shown below.
^{1 1} H NMR (CDCl ₃ , 400 MHz): δ 8.23 (s, 4 H), 7.45-7.42 (m, 4 H), 7.10-7.06 (m, 4 H), 5.68 (s, 4 H), 3.81 ( s, 12 H) ppm.
From this result, the target compound is the compound represented by the symbol 3 in FIG. 2 (5,7,9,14,16,18-hexahydro-19,20,21,22-tetracarboxymethyl-5,18: 9, It was confirmed to be 14-bisethenoheptasen-7,16-dione).

[Formation of compound 5 = process (ii), (iii)]
Under an ice bath, a 10% aqueous sodium hydroxide solution (10 ml) was added dropwise to a suspension of compound 3 (730 mg, 1.05 mmol) in methanol (15 ml). Then, the reaction solution was heated and stirred at 60 ° C. for 6 hours. After completion of the reaction, 6 M hydrochloric acid was added under an ice bath until the reaction solution became acidic. Further, ethyl acetate was added, and the organic layer obtained by the liquid separation operation was washed with saturated brine, dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was reprecipitated with ethyl acetate and hexane to give compound 4 in a crude yield of 668 mg.

The obtained compound 4 (700 mg) and copper powder (140 mg) were suspended in quinoline (12 ml), and the mixture was heated and stirred at 240 ° C. for 90 minutes with a microwave reactor. After completion of the reaction, the reaction solution was diluted with methylene chloride, and copper powder was removed by short column chromatography (methylene chloride). Next, this methylene chloride solution was washed with 3 M aqueous HCl solution and saturated brine. The organic layer was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica column chromatography fluffy (methylene chloride: hexane = 2: 1, Rf = 0.33), and reprecipitation was performed using methylene chloride and methanol to obtain the desired product in a yield of 54% (Methylene chloride: hexane = 2: 1, Rf = 0.33). 275 mg, 0.60 mmol) was isolated.

The desired product shows the result of structural analysis by ¹ H nuclear magnetic resonance spectroscopy as follows.
^{1 1} H NMR (CDCl ₃ , 400 MHz): δ 8.10 (s, 4H), 7.35-7.31 (m, 4 H), 7.05-6.98 (m, 8 H), 5.36-5.33 (m, 4 H) ppm.
From the above results, the target compound is the compound represented by symbol 5 in FIG. 2 (5,7,9,14,16,18-hexahydro-5,18: 9,14-bisethenoheptacene-7,16- Zeon) was confirmed.

[Formation of compound 6 = process (iv)]
Aluminum powder (729 mg, 27 mmol), mercury (II) chloride (15 mg, 0.06 mmol) and carbon tetrabromide (96 mg, 0.29 mmol) were added to cyclohexanol (14 ml) under an argon atmosphere at 160 ° C. Was heated and stirred for 5 hours. Then, the temperature was returned to room temperature, and compound 5 (560 mg, 1.22 mmol) was added. After heating again at 160 ° C. for 7 hours, the temperature was returned to room temperature, and the reaction solution was diluted with methylene chloride. After adding water to the reaction solution, the organic layer was washed with water and saturated brine, dried over sodium sulfate, and evaporated under reduced pressure. The obtained residue was reprecipitated with methylene chloride and methanol to isolate the desired product in a yield of 48% (251 mg, 0.58 mmol).
The desired product shows the result of structural analysis by ¹ H nuclear magnetic resonance spectroscopy as follows.
^{1 1} H NMR (CDCl ₃ , 400 MHz): δ 8.04 (s, 2 H), 7.70 (s, 4 H), 7.35-7.32 (m, 8 H), 7.02-6.99 (m, 4 H), 5.20 ( s, 4 H) ppm.
From the above results, it was confirmed that the target product was the compound represented by the symbol 6 in FIG. 2 (5,9,14,18-tetrahydro-5,18: 9,14-bisethenoheptacene).

[Formation of compound 7 = process (v)]
Compound 6 (96 mg, 0.29 mmol) was suspended in chloroform (180 ml) under an ice bath, and N-bromosuccinimide (816 mg, 4.58 mmol) was added over 5 minutes. The mixture was stirred under an ice bath for 10 minutes, saturated aqueous sodium hydrogen sulfite solution was added, and the reaction was stopped. The organic layer was washed with water and saturated brine, and dried over sodium sulfate. After distilling off the solvent under reduced pressure, the obtained residue was purified by silica column chromatography fluffy (methylene chloride: hexane = 1: 2, Rf = 0.48), and further precipitated with methylene chloride and methanol. The desired product was isolated in a yield of 20% (243 mg, 0.41 mmol).

The desired product shows the result of structural analysis by ¹ H nuclear magnetic resonance spectroscopy as follows.
^{1 1} H NMR (CDCl ₃ , 400 MHz): δ 8.31 (s, 2 H), 7.39-7.36 (m, 4 H), 7.05-7.01 (m, 8 H), 5.31-5.32 (m, 4 H) ppm ..
From the above results, the target compound is the compound represented by symbol 7 in FIG. 2 (7,16-dibromo-5,9,14,18-tetrahydro-5,18: 9,14-bisethenoheptasen). It was confirmed that.

[Formation of compound 8 = process (vi)]
Compound 7 (240 mg, 0.41 mmol) suspended in acetone (200 ml) under an ice bath with N-methylmorpholine-N-oxide (524 mg, 4.47 mmol) and microencapsulated osmium tetroxide (VIII) (23). An acetone solution (100 ml) of mg) was added dropwise over 5 minutes. The mixture was stirred under an ice bath for 15 minutes and then reacted at room temperature for 2 days. A saturated aqueous sodium dithionite solution was added to stop the reaction, the solvent was evaporated under reduced pressure, and then ethyl acetate was added. The ethyl acetate solution was washed with water and saturated brine, and dried over sodium sulfate. After distilling off the solvent under reduced pressure, the obtained residue was subjected to silica column chromatography fluffy (ethyl acetate: methylene chloride = 1: 5) to isolate the desired product in a yield of 95% (258 mg, 0.39 mmol). did. Of the target substances, the trans form was 158 mg (Rf = 0.50 and 0.38), and the cis form was 100 mg (Rf = 0.25).

For trans isomer and cis-isomer, shows the result of structural analysis by ¹ H nuclear magnetic resonance spectroscopy as follows.
Transformer body
^{1 1} H NMR (DMSO-d6, 500 MHz): δ 8.36 (s, 2 H), 7.46-7.45 (m, 4 H), 7.18-7.16 (m, 4 H), 4.87 (s, 4 H), 4.65 (s, 4 H), 3.99 (s, 4 H) ppm.
Sis body
^{1 1} H NMR (DMSO-d6, 500 MHz): δ 8.35 (s, 2 H), 7.45-7.43 (m, 4 H), 7.20-7.18 (m, 4 H), 4.90 (s, 4 H), 4.65 (s, 4 H), 4.00 (s, 4 H) ppm.
From the above results, the target product is the compound represented by symbol 8 in FIG. 2 (7,16-dibromo-5,9,14,18-tetrahydro-19,20,21,22-tetrahydroxy-5,18. : 9,14-Bis etanoheptasen) was confirmed.

[Compound 1 = Preparation of higher-order acene derivative = Process (vii)]
Trifluoroacetic anhydride (1 ml) was added dropwise at −78 ° C. over 10 minutes to a mixed solution of dimethyl sulfoxide (5 ml) and methylene chloride (15 ml) under an argon atmosphere. 45 minutes after the completion of the dropwise addition, the trans compound compound 8 (100 mg, 0.15 mmol) dissolved in a mixed solvent of dimethyl sulfoxide (15 ml) and methylene chloride (50 ml) was added dropwise over 40 minutes at -78 ° C. Stirred for 2 hours. Then, the reaction was stopped by dropping diisopropylethylamine over 5 minutes, and the reaction solution was returned to room temperature. This reaction solution was added to a 3 M aqueous HCl solution and extracted with methylene chloride. After separating the organic layer, the organic layer was washed with water and saturated brine, and dried over sodium sulfate. After distilling off the solvent under reduced pressure, the obtained residue was subjected to silica column chromatography fluffy (ethyl acetate: methylene chloride = 1: 5, Rf = 0.70), and further precipitated with methylene chloride and heptane. The product was isolated in a yield of 73% (73 mg, 0.11 mmol).

The results of structural analysis of the target object by the nuclear magnetic resonance spectral method are shown below.
^{1 1} H NMR (CDCl ₃ , 600 MHz): δ 8.67 (s, 2 H), 7.57-7.54 (m, 4 H), 7.45-7.43 (m, 4 H), 5.31 (s, 4 H) ppm.
From the above results, the target compound is the compound represented by symbol 1 in FIG. 2 (7,16-dibromo-5,9,14,18-tetrahydro-5,18: 9,14-bisethanoheptacene-19. , 20,21,22-tetraketone) was confirmed.

As described above, a higher-order acene derivative can be produced by introducing a bromo substituent into the higher-order acene as a starting material in advance and proceeding with the synthesis by the method according to the present invention. By using this higher-order acene derivative, it is possible to easily prepare a GNR having a uniform width, in which linkage is unlikely to occur except for the bromo substituent of the central benzene ring.

In the above example, a bromo group was introduced at the 1st and 4th positions of the central benzene ring of the higher acene derivative, but a halogen other than the bromo group (element of the 17th group of the periodic table) may be introduced. Among halogens, fluorine, chlorine, bromo, and iodine are known to have very similar chemical properties. Therefore, any of fluorine group, chlorine group, and iodine group was introduced instead of the bromo group. Even in this case, it is presumed that the same result as in the above embodiment can be obtained.
Further, in the above embodiment, a synthesis example of a higher-order acene derivative (heptacene derivative) in which 7 benzene rings are linearly arranged has been described, but an appropriate odd number such as 3 or 5 or 9 benzene rings has been described. It is presumed that the same results as in the above-mentioned Examples can be obtained for the derivative of higher-order acene in which the benzene rings of benzene are arranged in a straight line.
Further, in the present specification, the usefulness of the higher-order acene derivative according to the present invention as a material compound of GNR has been described, but this does not deny the possibility of using it for substances other than GNR.

In the present invention, the 1st and 4th positions of the central benzene ring of higher-order acene in which three or more odd benzene rings are linearly condensed are replaced with halogens (fluorine group, chlorine group, bromo group, iodine group). Provided is a novel higher-order acene derivative in which a diketone is crosslinked between the 1-position and the 4-position of each one benzene ring located symmetrically on both sides of the central benzene ring. Due to such a characteristic structure, the higher-order acene derivative according to the present invention tends to form a polymer chain that is correctly arranged side by side and has a possibility of being used as a material for graphene nanoribbons.

Claims (1)

a) Dimethyl acetylenedicarboxylate (DMAD) was crosslinked and added to 7,16-heptasenquinone by the Diels-Alder reaction.
b) Remove the ester group at the crosslinked part by decarboxylation reaction.
c) The oxygen of the quinone is removed by the reduction reaction and a bromo group is added to the isotope.
d) Oxygen was added to the crosslinked part by the oxidation reaction, and 7,16-dibromo-5,9,14,18-tetrahydro-5,18: 9,14-bisethanoheptacene-19,20,21,22- Forming tetraketone,
A method for producing a higher-order acene derivative, which comprises a step of adding oxygen to a crosslinked portion by an oxidation reaction, which comprises hydroxylating the crosslinked portion and further oxidizing the crosslinked portion.

Images