JP6146860B2 - Metal complex and fuel cell cathode containing the same - Google Patents
Metal complex and fuel cell cathode containing the same Download PDFInfo
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- JP6146860B2 JP6146860B2 JP2013121811A JP2013121811A JP6146860B2 JP 6146860 B2 JP6146860 B2 JP 6146860B2 JP 2013121811 A JP2013121811 A JP 2013121811A JP 2013121811 A JP2013121811 A JP 2013121811A JP 6146860 B2 JP6146860 B2 JP 6146860B2
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- metal complex
- independently
- integer
- oxygen
- carbon atoms
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- 150000004696 coordination complex Chemical class 0.000 title claims description 85
- 239000000446 fuel Substances 0.000 title claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 68
- 239000001301 oxygen Substances 0.000 claims description 68
- 229910052760 oxygen Inorganic materials 0.000 claims description 68
- 125000004432 carbon atom Chemical group C* 0.000 claims description 28
- 238000006243 chemical reaction Methods 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 229910052799 carbon Inorganic materials 0.000 claims description 16
- 125000000217 alkyl group Chemical group 0.000 claims description 15
- 239000003054 catalyst Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 8
- 150000001450 anions Chemical class 0.000 claims description 7
- 239000003446 ligand Substances 0.000 claims description 7
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 5
- 150000001768 cations Chemical class 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910020366 ClO 4 Inorganic materials 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000006722 reduction reaction Methods 0.000 description 51
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 36
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 18
- 230000009467 reduction Effects 0.000 description 15
- 239000000243 solution Substances 0.000 description 15
- 239000000126 substance Substances 0.000 description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- -1 ferrocenium ion Chemical class 0.000 description 14
- 150000002430 hydrocarbons Chemical group 0.000 description 13
- 125000003367 polycyclic group Chemical group 0.000 description 13
- 239000000843 powder Substances 0.000 description 13
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 12
- JFDZBHWFFUWGJE-UHFFFAOYSA-N benzonitrile Chemical compound N#CC1=CC=CC=C1 JFDZBHWFFUWGJE-UHFFFAOYSA-N 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 12
- 238000003786 synthesis reaction Methods 0.000 description 12
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- 238000010992 reflux Methods 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 description 8
- 239000003638 chemical reducing agent Substances 0.000 description 8
- 229940125904 compound 1 Drugs 0.000 description 8
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 8
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 7
- 238000002484 cyclic voltammetry Methods 0.000 description 7
- KTWOOEGAPBSYNW-UHFFFAOYSA-N ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- YLEIFZAVNWDOBM-ZTNXSLBXSA-N ac1l9hc7 Chemical compound C([C@H]12)C[C@@H](C([C@@H](O)CC3)(C)C)[C@@]43C[C@@]14CC[C@@]1(C)[C@@]2(C)C[C@@H]2O[C@]3(O)[C@H](O)C(C)(C)O[C@@H]3[C@@H](C)[C@H]12 YLEIFZAVNWDOBM-ZTNXSLBXSA-N 0.000 description 6
- BOXSCYUXSBYGRD-UHFFFAOYSA-N cyclopenta-1,3-diene;iron(3+) Chemical compound [Fe+3].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 BOXSCYUXSBYGRD-UHFFFAOYSA-N 0.000 description 6
- 229910052697 platinum Inorganic materials 0.000 description 6
- 125000001424 substituent group Chemical group 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 238000002848 electrochemical method Methods 0.000 description 5
- ROFVEXUMMXZLPA-UHFFFAOYSA-N Bipyridyl Chemical group N1=CC=CC=C1C1=CC=CC=N1 ROFVEXUMMXZLPA-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 150000001721 carbon Chemical group 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical class CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000007306 turnover Effects 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 238000005481 NMR spectroscopy Methods 0.000 description 3
- 238000002835 absorbance Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000012153 distilled water Substances 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000001308 synthesis method Methods 0.000 description 3
- 229910052727 yttrium Inorganic materials 0.000 description 3
- QDRMVEFETHGPKI-UHFFFAOYSA-N (5-borono-2,7-ditert-butyl-9,9-dimethylxanthen-4-yl)boronic acid Chemical compound C1=C(C(C)(C)C)C=C2C(C)(C)C3=CC(C(C)(C)C)=CC(B(O)O)=C3OC2=C1B(O)O QDRMVEFETHGPKI-UHFFFAOYSA-N 0.000 description 2
- AJKVQEKCUACUMD-UHFFFAOYSA-N 2-Acetylpyridine Chemical compound CC(=O)C1=CC=CC=N1 AJKVQEKCUACUMD-UHFFFAOYSA-N 0.000 description 2
- HKOAFLAGUQUJQG-UHFFFAOYSA-N 2-pyrimidin-2-ylpyrimidine Chemical group N1=CC=CN=C1C1=NC=CC=N1 HKOAFLAGUQUJQG-UHFFFAOYSA-N 0.000 description 2
- OJJSJAIHWCFVBK-UHFFFAOYSA-N 4,5-dibromo-2,7-ditert-butyl-9,9-dimethylxanthene Chemical compound C1=C(C(C)(C)C)C=C2C(C)(C)C3=CC(C(C)(C)C)=CC(Br)=C3OC2=C1Br OJJSJAIHWCFVBK-UHFFFAOYSA-N 0.000 description 2
- 102000000634 Cytochrome c oxidase subunit IV Human genes 0.000 description 2
- 108090000365 Cytochrome-c oxidases Proteins 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 238000001237 Raman spectrum Methods 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- DGEZNRSVGBDHLK-UHFFFAOYSA-N [1,10]phenanthroline Chemical group C1=CN=C2C3=NC=CC=C3C=CC2=C1 DGEZNRSVGBDHLK-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 2
- ZSWFCLXCOIISFI-UHFFFAOYSA-N cyclopentadiene Chemical group C1C=CC=C1 ZSWFCLXCOIISFI-UHFFFAOYSA-N 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000000655 nuclear magnetic resonance spectrum Methods 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 238000000967 suction filtration Methods 0.000 description 2
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 2
- QKLXBIHSGMPUQS-FGZHOGPDSA-M (3r,5r)-7-[4-(4-fluorophenyl)-2,5-dimethyl-1-phenylpyrrol-3-yl]-3,5-dihydroxyheptanoate Chemical compound CC1=C(CC[C@@H](O)C[C@@H](O)CC([O-])=O)C(C=2C=CC(F)=CC=2)=C(C)N1C1=CC=CC=C1 QKLXBIHSGMPUQS-FGZHOGPDSA-M 0.000 description 1
- QTKIQLNGOKOPOE-UHFFFAOYSA-N 1,1'-biphenyl;propane Chemical group CCC.C1=CC=CC=C1C1=CC=CC=C1 QTKIQLNGOKOPOE-UHFFFAOYSA-N 0.000 description 1
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 1
- 239000005695 Ammonium acetate Substances 0.000 description 1
- NBIXGGAXQJRYSC-UHFFFAOYSA-N C(C)(C)(C)C1=CC=2C(C3=CC(=CC=C3OC2C=C1)C(C)(C)C)(C)C.N1=C(C=CC=C1)C1=NC=CC=C1C1=NC=CC=C1 Chemical compound C(C)(C)(C)C1=CC=2C(C3=CC(=CC=C3OC2C=C1)C(C)(C)C)(C)C.N1=C(C=CC=C1)C1=NC=CC=C1C1=NC=CC=C1 NBIXGGAXQJRYSC-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910002549 Fe–Cu Inorganic materials 0.000 description 1
- 101000578940 Homo sapiens PDZ domain-containing protein MAGIX Proteins 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- VLIXVDTXTZTYNE-UHFFFAOYSA-N N1=C(C=CC=C1)C(C=CC1=CC=CC2=CC3=CC=CC(=C3C=C12)C=CC(C1=NC=CC=C1)=O)=O Chemical compound N1=C(C=CC=C1)C(C=CC1=CC=CC2=CC3=CC=CC(=C3C=C12)C=CC(C1=NC=CC=C1)=O)=O VLIXVDTXTZTYNE-UHFFFAOYSA-N 0.000 description 1
- AWZICBRXAMNMNQ-UHFFFAOYSA-N N1=C(C=CC=C1)C(CC(CC(=O)C1=NC=CC=C1)C1=CC=CC2=CC3=CC=CC(=C3C=C12)C(CC(C1=NC=CC=C1)=O)CC(C1=NC=CC=C1)=O)=O Chemical compound N1=C(C=CC=C1)C(CC(CC(=O)C1=NC=CC=C1)C1=CC=CC2=CC3=CC=CC(=C3C=C12)C(CC(C1=NC=CC=C1)=O)CC(C1=NC=CC=C1)=O)=O AWZICBRXAMNMNQ-UHFFFAOYSA-N 0.000 description 1
- 102100028326 PDZ domain-containing protein MAGIX Human genes 0.000 description 1
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical group C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- NVJHHSJKESILSZ-UHFFFAOYSA-N [Co].N1C(C=C2N=C(C=C3NC(=C4)C=C3)C=C2)=CC=C1C=C1C=CC4=N1 Chemical compound [Co].N1C(C=C2N=C(C=C3NC(=C4)C=C3)C=C2)=CC=C1C=C1C=CC4=N1 NVJHHSJKESILSZ-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- SRVFFFJZQVENJC-IHRRRGAJSA-N aloxistatin Chemical compound CCOC(=O)[C@H]1O[C@@H]1C(=O)N[C@@H](CC(C)C)C(=O)NCCC(C)C SRVFFFJZQVENJC-IHRRRGAJSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 229940043376 ammonium acetate Drugs 0.000 description 1
- 235000019257 ammonium acetate Nutrition 0.000 description 1
- UFEHDZBGPNZLQG-UHFFFAOYSA-N anthracene-1,8-dicarbaldehyde Chemical compound C1=CC(C=O)=C2C=C3C(C=O)=CC=CC3=CC2=C1 UFEHDZBGPNZLQG-UHFFFAOYSA-N 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- SPKJCVZOZISLEI-UHFFFAOYSA-N cyclopenta-1,3-diene;1-cyclopenta-1,3-dien-1-ylethanone;iron(2+) Chemical compound [Fe+2].C=1C=C[CH-]C=1.CC(=O)C1=CC=C[CH-]1 SPKJCVZOZISLEI-UHFFFAOYSA-N 0.000 description 1
- SRXXWRNTLKDBGA-UHFFFAOYSA-N cyclopenta-1,3-diene;cyclopenta-2,4-dien-1-ylidenemethylideneazanide;iron(2+) Chemical compound [Fe+2].C=1C=C[CH-]C=1.N#CC1=CC=C[CH-]1 SRXXWRNTLKDBGA-UHFFFAOYSA-N 0.000 description 1
- WMKGGPCROCCUDY-PHEQNACWSA-N dibenzylideneacetone Chemical compound C=1C=CC=CC=1\C=C\C(=O)\C=C\C1=CC=CC=C1 WMKGGPCROCCUDY-PHEQNACWSA-N 0.000 description 1
- ZOCHARZZJNPSEU-UHFFFAOYSA-N diboron Chemical compound B#B ZOCHARZZJNPSEU-UHFFFAOYSA-N 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000002330 electrospray ionisation mass spectrometry Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910021397 glassy carbon Inorganic materials 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- SEYZDJPFVVXSRB-UHFFFAOYSA-N iron(2+);1,2,3,4,5-pentamethylcyclopenta-1,3-diene Chemical compound [Fe+2].CC=1C(C)=C(C)[C-](C)C=1C.CC=1C(C)=C(C)[C-](C)C=1C SEYZDJPFVVXSRB-UHFFFAOYSA-N 0.000 description 1
- KYMNSBSWJPFUJH-UHFFFAOYSA-N iron;5-methylcyclopenta-1,3-diene;methylcyclopentane Chemical compound [Fe].C[C-]1C=CC=C1.C[C-]1[CH-][CH-][CH-][CH-]1 KYMNSBSWJPFUJH-UHFFFAOYSA-N 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- DLEDOFVPSDKWEF-UHFFFAOYSA-N lithium butane Chemical compound [Li+].CCC[CH2-] DLEDOFVPSDKWEF-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- MZRVEZGGRBJDDB-UHFFFAOYSA-N n-Butyllithium Substances [Li]CCCC MZRVEZGGRBJDDB-UHFFFAOYSA-N 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- AICOOMRHRUFYCM-ZRRPKQBOSA-N oxazine, 1 Chemical compound C([C@@H]1[C@H](C(C[C@]2(C)[C@@H]([C@H](C)N(C)C)[C@H](O)C[C@]21C)=O)CC1=CC2)C[C@H]1[C@@]1(C)[C@H]2N=C(C(C)C)OC1 AICOOMRHRUFYCM-ZRRPKQBOSA-N 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 150000004032 porphyrins Chemical class 0.000 description 1
- LPNYRYFBWFDTMA-UHFFFAOYSA-N potassium tert-butoxide Chemical compound [K+].CC(C)(C)[O-] LPNYRYFBWFDTMA-UHFFFAOYSA-N 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 150000003222 pyridines Chemical class 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000029058 respiratory gaseous exchange Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- KBLZDCFTQSIIOH-UHFFFAOYSA-M tetrabutylazanium;perchlorate Chemical compound [O-]Cl(=O)(=O)=O.CCCC[N+](CCCC)(CCCC)CCCC KBLZDCFTQSIIOH-UHFFFAOYSA-M 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 125000001834 xanthenyl group Chemical group C1=CC=CC=2OC3=CC=CC=C3C(C12)* 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Landscapes
- Inert Electrodes (AREA)
- Pyridine Compounds (AREA)
- Plural Heterocyclic Compounds (AREA)
Description
本発明は、金属錯体およびこれを含む燃料電池用カソードに関する。 The present invention relates to a metal complex and a fuel cell cathode containing the same.
深刻なエネルギー問題および環境問題に直面している現在、新たな発電システムとして燃料電池に大きな期待が寄せられている。燃料としては、水素が最も一般的に使用されるが、この他にもメタノールまたはグルコースを使用する燃料電池も開発されている。燃料電池では、アノードで起きる燃料物質の酸化反応と、カソードで起きる還元反応の電位差分だけ起電力が得られる。総ての燃料電池において、カソード反応は酸素還元反応である。これは酸素が空気中に多量に存在し入手しやすい物質であるばかりではなく、水へ還元される平衡電極電位が＋１．２２９Ｖ（ｖｓ．ＮＨＥ、ｐＨ０）と正側であることが主たる理由である。水素、メタノール、グルコースが酸化される平衡電極電位はいずれもほぼ０Ｖであるから、起電力はカソード反応に依存する。従って、できる限り平衡電極電位に近い電位で酸素を還元することが望まれる。具体的には、平衡電極電位（＋１．２２９Ｖ ｖｓ．ＮＨＥ、ｐＨ０）に近い電位で酸素を４電子還元することが望まれる（スキーム１）。ところが、酸素還元反応では酸素を還元し過酸化水素を生成する反応（スキーム２）も生じる可能性がある。スキーム２の反応における平衡電極電位は＋０．６９５Ｖ（ｖｓ．ＮＨＥ、ｐＨ０）と比較的負側であるため、過酸化水素を発生する割合が大きいほど酸素還元反応が進行する電位も負側になり、燃料電池としての性能が低下する。さらに、過酸化水素は燃料電池を劣化させる。よって、過酸化水素を発生せずに正電位で酸素を還元できる触媒が要求されている。現在のところ、このような要求を満たす触媒として、白金あるいは白金を主とする合金が一般的に用いられているが、これ以外の触媒が望まれている。 In the face of serious energy and environmental problems, there is a great expectation for fuel cells as a new power generation system. Hydrogen is most commonly used as the fuel, but other fuel cells using methanol or glucose have also been developed. In a fuel cell, an electromotive force can be obtained by a potential difference between an oxidation reaction of a fuel substance occurring at an anode and a reduction reaction occurring at a cathode. In all fuel cells, the cathode reaction is an oxygen reduction reaction. This is mainly due to the fact that oxygen is not only a large quantity in the air and is easily available, but the equilibrium electrode potential to be reduced to water is +1.229 V (vs. NHE, pH 0) and positive. is there. Since the equilibrium electrode potential at which hydrogen, methanol and glucose are oxidized is almost 0 V, the electromotive force depends on the cathode reaction. Therefore, it is desirable to reduce oxygen at a potential as close to the equilibrium electrode potential as possible. Specifically, it is desired to perform 4-electron reduction of oxygen at a potential close to the equilibrium electrode potential (+1.229 V vs. NHE, pH 0) (Scheme 1). However, in the oxygen reduction reaction, there may be a reaction (Scheme 2) in which oxygen is reduced to generate hydrogen peroxide. Since the equilibrium electrode potential in the reaction of Scheme 2 is relatively negative at +0.695 V (vs. NHE, pH 0), the potential at which the oxygen reduction reaction proceeds becomes negative as the hydrogen peroxide generation rate increases. The performance as a fuel cell is reduced. Furthermore, hydrogen peroxide degrades the fuel cell. Therefore, there is a need for a catalyst that can reduce oxygen at a positive potential without generating hydrogen peroxide. At present, platinum or an alloy mainly composed of platinum is generally used as a catalyst that satisfies such requirements, but other catalysts are desired.
ところで、好気性生物の呼吸において、鉄と銅の２核錯体を活性中心とするシトクロムｃ酸化酵素が酸素の還元を行っていることが知られており、遷移金属錯体が酸素還元触媒として機能することが期待される。実際に、非特許文献１にはシトクロムｃ酸化酵素の構造をモデルとしたＦｅ−Ｃｕ錯体（化学式ｉ）が、非特許文献２および３にはＣｏを中心金属とするポルフィリン（化学式ｉｉ）が、非特許文献４にはコロール錯体（化学式ｉｉｉ）が、非特許文献５には複数の金属を含有する高分子錯体（化学式ｉｖ）が、酸素を４電子還元して水を生成することが報告されている。 By the way, it is known that cytochrome c oxidase having an active center of a binuclear complex of iron and copper performs oxygen reduction in respiration of an aerobic organism, and the transition metal complex functions as an oxygen reduction catalyst. It is expected. In fact, Non-Patent Document 1 shows an Fe-Cu complex (chemical formula i) modeled on the structure of cytochrome c oxidase, and Non-Patent Documents 2 and 3 show porphyrin (chemical formula ii) having Co as a central metal. Non-Patent Document 4 reports that a corol complex (chemical formula iii) is produced, and Non-patent Document 5 reports that a polymer complex (chemical formula iv) containing a plurality of metals produces water by 4-electron reduction of oxygen. ing.
しかしながら、前記文献に記載された金属錯体を用いた酸素還元反応では水とともに一定量の過酸化水素が生成する。酸素還元反応における過酸化水素の発生量は、回転リングディスク電極を用いた電気化学測定により確認できる。回転リングディスク電極とは、ディスク状の炭素電極と、その外側に配置されたリング状の白金電極からなる電極である。詳細は後述するが、回転リングディスク電極を用いた電気化学測定は、１）金属錯体を炭素電極（ディスク電極）上に担持して、酸素を含む水に浸し、一定の速度で電極を回転させながらディスク電極の電位を正側から負側へ掃引する、２）酸素還元反応により生じた水以外の活性酸素種（過酸化水素等）を遠心力によってリング電極上に移動させる、３）リング電極に電位をかけて活性酸素種のみを酸化し、その際にリング電極上に流れる電流の大きさから、活性酸素種の発生量を特定する、という手順で行なわれる。すなわち、リング電極の電流値が大きいほど過酸化水素等が生成していることになる。 However, in the oxygen reduction reaction using the metal complex described in the above document, a certain amount of hydrogen peroxide is generated together with water. The amount of hydrogen peroxide generated in the oxygen reduction reaction can be confirmed by electrochemical measurement using a rotating ring disk electrode. The rotating ring disk electrode is an electrode composed of a disk-shaped carbon electrode and a ring-shaped platinum electrode arranged on the outside thereof. Although details will be described later, electrochemical measurement using a rotating ring disk electrode is as follows: 1) A metal complex is supported on a carbon electrode (disk electrode), immersed in water containing oxygen, and the electrode is rotated at a constant speed. 2) The potential of the disk electrode is swept from the positive side to the negative side. 2) Active oxygen species other than water (hydrogen peroxide, etc.) generated by the oxygen reduction reaction are moved onto the ring electrode by centrifugal force. 3) The ring electrode. A potential is applied to oxidize only the active oxygen species, and the generation amount of the active oxygen species is specified from the magnitude of the current flowing on the ring electrode. That is, as the current value of the ring electrode increases, hydrogen peroxide and the like are generated.
例えば、非特許文献３には、コバルト−ポルフィンリンをキサンテン骨格で架橋した化学式（ｉｉｉ）の金属錯体について、回転リングディスク電極を用いて電気化学測定を行なったところ、酸素還元反応が進行すると同時にリング電極での電流が上昇することが報告されている（図１参照）。図１は、＋０．５Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）以下の電位においてディスク電極電流が増加すると同時にリング電極電流も増加することを示す。このことから酸素還元反応において過酸化水素が生成していることが分かる。 For example, Non-Patent Document 3 discloses that when a metal complex having the chemical formula (iii) obtained by crosslinking cobalt-porphine with a xanthene skeleton is subjected to electrochemical measurement using a rotating ring disk electrode, an oxygen reduction reaction proceeds. It has been reported that the current at the ring electrode increases (see FIG. 1). FIG. 1 shows that the ring electrode current increases at the same time as the disk electrode current increases at a potential of +0.5 V (vs. Ag / AgCl) or less. This shows that hydrogen peroxide is generated in the oxygen reduction reaction.
このように、従来知られている金属錯体は、酸素還元反応において過酸化水素を生成させやすい。このことに鑑み、本発明は、過酸化水素を発生させずに速やかに酸素を水へ還元しうる活性を有する金属錯体を提供することを課題とする。 Thus, conventionally known metal complexes are likely to generate hydrogen peroxide in the oxygen reduction reaction. In view of this, an object of the present invention is to provide a metal complex having an activity capable of quickly reducing oxygen to water without generating hydrogen peroxide.
発明者らは鋭意検討の結果、特定の金属錯体が上記課題を解決できることを見出し、本発明を完成した。すなわち、前記課題は以下の本発明により解決される。
［１］後述する一般式（Ｉ）で表される金属錯体。
［２］後述する一般式（１）で表される化合物と、ＣｏＳＯ４またはＦｅＳＯ４とを混合しながら加熱する工程、
前記反応系に、酸素と、後述する一般式（２ａ）、（２ｂ）、または（２ｃ）で表される化合物とを加え、加熱する工程、および
前記反応系にＺｎ・Ｙ−ｎで表される塩（Ｚｎはｎ価のカチオンであり、Ｙおよびｎは前述のとおり定義される）を加える工程、を含む、［１］に記載の金属錯体の製造方法。
［３］前記［１］に記載の金属錯体を含む、燃料電池用カソード。
［４］前記［３］に記載のカソードを備える燃料電池。
［５］前記［１］に記載の金属錯体を触媒として用いる、酸素を水に還元する方法。
As a result of intensive studies, the inventors have found that a specific metal complex can solve the above problems, and have completed the present invention. That is, the said subject is solved by the following this invention.
[1] A metal complex represented by the following general formula (I).
[2] A step of heating while mixing a compound represented by the general formula (1) described later and CoSO 4 or FeSO 4 ;
Table in the reaction system, oxygen, described below general formula (2a), (2b), or a compound represented by the added (2c), heating, and Z n · Y -n to the reaction system The method for producing a metal complex according to [1], comprising a step of adding a salt (Z n is an n-valent cation, and Y and n are defined as described above).
[3] A fuel cell cathode comprising the metal complex according to [1].
[4] A fuel cell comprising the cathode according to [3].
[5] A method for reducing oxygen to water using the metal complex according to [1] as a catalyst.
本発明により、過酸化水素を発生させずに速やかに酸素を水へ還元しうる活性を有する金属錯体を提供できる。 According to the present invention, a metal complex having an activity capable of quickly reducing oxygen to water without generating hydrogen peroxide can be provided.
以下、本発明を説明する。本発明において「〜」はその両端の値を含む。
１．金属錯体
本発明の金属錯体は、一般式（Ｉ）で表される。
The present invention will be described below. In the present invention, “to” includes values at both ends thereof.
1. Metal Complex The metal complex of the present invention is represented by the general formula (I).
式中、ＭはＣｏまたはＦｅである。
式（ｙ）で表される結合は、二重結合または単結合を示す。
In the formula, M is Co or Fe.
The bond represented by the formula (y) represents a double bond or a single bond.
Ｘは、炭素原子または酸素原子である。Ｘが炭素原子である場合は、Ｘを含む多環炭化水素基（以下単に「多環炭化水素基」ともいう）は、１，８−アントラセンジイル基であることが好ましい。すなわち、式（ｙ）で表される結合はすべて二重結合であることが好ましい。Ｘが酸素原子である場合は、多環炭化水素基は、４，５−キサンテンジイル基であることが好ましい。すなわち、式（ｙ）で表される結合はすべて単結合であることが好ましい。 X is a carbon atom or an oxygen atom. When X is a carbon atom, the polycyclic hydrocarbon group containing X (hereinafter also simply referred to as “polycyclic hydrocarbon group”) is preferably a 1,8-anthracenediyl group. That is, all the bonds represented by the formula (y) are preferably double bonds. When X is an oxygen atom, the polycyclic hydrocarbon group is preferably a 4,5-xanthenediyl group. That is, all the bonds represented by formula (y) are preferably single bonds.
Ｒ３は多環炭化水素基に結合する炭素数が１〜４のアルキル基である。多環炭化水素基が１，８−アントラセンジイル基である場合、Ｒ３は２〜７位の炭素原子に結合する。本発明においてアルキル基は異性体も含むので、炭素数が１〜４のアルキル基とは、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、またはｔ−ブチル基である。ｈはＲ３のベンゼン環上の個数を示し、独立に０〜３の整数である。「ｈは独立に０〜３の整数である」とは、式（Ｉ）において右に存在するｈと左に存在するｈの値が、同一または異なることを意味する。Ｒ３の数が多いと立体障害により金属錯体が化学的に不安定になる場合があるのでｈは０〜１が好ましく、０がより好ましい。またＲ３が存在する場合、嵩高いと立体障害により金属錯体が化学的に不安定になる場合があるのでこの観点からはＲ３はメチル基であることが好ましい。一方、多環炭化水素基が芳香環でない場合は多環炭化水素基が屈曲しやすいので、これに結合する二つのターピリジル基が接近して不安定になる場合がある。このためＲ３が比較的嵩高いとＲ３同士の反発により多環炭化水素基の屈曲が抑制されるので、安定性が向上するという利点がある。この場合、Ｒ３はプロピル基、ブチル基であることが好ましく、ブチル基であることがより好ましい。
ただし、２位および７位にＲ３が存在すると、合成が困難となる場合があるので、Ｒ３は２位および７位には存在しないことが好ましい。
R 3 is an alkyl group having 1 to 4 carbon atoms bonded to the polycyclic hydrocarbon group. When the polycyclic hydrocarbon group is a 1,8-anthracenediyl group, R 3 is bonded to a carbon atom at the 2-7 position. In the present invention, an alkyl group includes an isomer, and therefore an alkyl group having 1 to 4 carbon atoms is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or a t-butyl group. It is a group. h represents the number of R 3 on the benzene ring and is independently an integer of 0 to 3. “H is independently an integer of 0 to 3” means that the value of h present on the right and the value of h present on the left in the formula (I) are the same or different. If the number of R 3 is large, the metal complex may become chemically unstable due to steric hindrance, so h is preferably 0 to 1, and more preferably 0. When R 3 is present, if it is bulky, the metal complex may be chemically unstable due to steric hindrance. Therefore, from this viewpoint, R 3 is preferably a methyl group. On the other hand, when the polycyclic hydrocarbon group is not an aromatic ring, the polycyclic hydrocarbon group tends to bend, so that the two terpyridyl groups bonded thereto may approach and become unstable. For this reason, when R 3 is relatively bulky, bending of the polycyclic hydrocarbon group is suppressed due to repulsion between R 3, so that there is an advantage that stability is improved. In this case, R 3 is preferably a propyl group or a butyl group, and more preferably a butyl group.
However, if R 3 is present in the 2-position and 7-position, because it may synthesis is difficult, R 3 is preferably not present in the 2 and 7 positions.
Ｒ４は多環炭化水素基に結合する炭素数が１〜３のアルキル基である。ｉはＲ４の個数を示し、０〜２の整数である。多環炭化水素基が１，８−アントラセンジイル基である場合、Ｒ４は９および１０位の炭素原子に結合できる。前述の理由から、ｉは０〜１が好ましく、０がより好ましい。またＲ４が存在する場合はメチル基であることが好ましい。多環炭化水素基が４，５−キサンテンジイル基である場合、Ｒ４は９位の炭素原子に結合できる。Ｒ４はメチル基が好ましく、ｉは２が好ましい。 R 4 is an alkyl group having 1 to 3 carbon atoms bonded to the polycyclic hydrocarbon group. i represents the number of R 4, it is an integer of 0-2. When the polycyclic hydrocarbon group is a 1,8-anthracenediyl group, R 4 can be bonded to the 9 and 10-position carbon atoms. For the reasons described above, i is preferably 0 to 1, and more preferably 0. When R 4 is present, it is preferably a methyl group. When the polycyclic hydrocarbon group is a 4,5-xanthenediyl group, R 4 can be bonded to the 9th carbon atom. R 4 is preferably a methyl group, and i is preferably 2.
Ｒ５〜Ｒ７は２，２’：６’２’’−ターピリジル基の、３〜６位の炭素原子、３’と５’位の炭素原子、および３’’〜６’’位の炭素原子にそれぞれ結合する炭素数が１〜３のアルキル基である。ｊ、ｋ、およびｌはこれらの基の個数を示し、それぞれ独立に０〜３の整数、０〜２の整数、および０〜３の整数である。前述の理由から、ｊ、ｋ、およびｌは０〜１が好ましく、０がより好ましい。またＲ５〜Ｒ７はが存在する場合はメチル基であることが好ましい。ただし、Ｒ６が存在すると、合成が困難となる場合があるので、Ｒ６は存在しないことが好ましい。
Ｌは一般式（Ｉａ）、（Ｉｂ）、または（Ｉｃ）で表される二座配位子である。
R 5 to R 7 are carbon atoms at positions 3 to 6 and carbon atoms at positions 3 ′ and 5 ′ and carbons at positions 3 ″ to 6 ″ of the 2,2 ′: 6′2 ″ -terpyridyl group. It is an alkyl group having 1 to 3 carbon atoms bonded to each atom. j, k, and l represent the number of these groups, and are independently an integer of 0 to 3, an integer of 0 to 2, and an integer of 0 to 3, respectively. For the reasons described above, j, k, and l are preferably 0 to 1, and more preferably 0. Moreover, when R < 5 > -R < 7 > exists, it is preferable that it is a methyl group. However, when R 6 is present, because it may synthesis becomes difficult, it is preferable not to R 6 is present.
L is a bidentate ligand represented by the general formula (Ia), (Ib), or (Ic).
Ｉａは２，２’−ジピリジン骨格を有する二座配位子である。式中のＮ原子から延びる線は、当該Ｎ元素が金属に配位していることを意味する。Ｒ１は３〜６位の炭素原子および３’〜６’位の炭素原子に結合する炭素数１〜３のアルキル基である。ｄはＲ１の個数を示し、独立に０〜４の整数である。合成が容易であるという観点からｄは０〜１が好ましく、０がより好ましい。一方で、ピリジン環に置換基が導入されていると当該置換基と前記ターピリジル基との間で相互作用が生じて金属錯体の安定性が増加しうる。しかしながら、置換基が過度に嵩高いまたは過度に多いとこの安定効果が得られにくいので、Ｒ１が存在する場合はメチル基であることが好ましい。この場合、ｄは１〜２が好ましく、１がより好ましい。特に２，２’−ジピリジンにおける６および６’位の炭素原子にＲ１が結合することが好ましい。 Ia is a bidentate ligand having a 2,2′-dipyridine skeleton. The line extending from the N atom in the formula means that the N element is coordinated to the metal. R 1 is an alkyl group having 1 to 3 carbon atoms bonded to 3 to 6 carbon atoms and 3 ′ to 6 ′ carbon atoms. d shows the number of R 1 and is an integer of 0-4 independently. From the viewpoint of easy synthesis, d is preferably 0 to 1, and more preferably 0. On the other hand, when a substituent is introduced into the pyridine ring, an interaction occurs between the substituent and the terpyridyl group, thereby increasing the stability of the metal complex. However, when the substituent is excessively bulky or excessively large, it is difficult to obtain this stabilizing effect. Therefore, when R 1 is present, a methyl group is preferable. In this case, d is preferably 1 to 2, and more preferably 1. In particular, R 1 is preferably bonded to carbon atoms at the 6 and 6 ′ positions in 2,2′-dipyridine.
Ｉｂは２，２’−ジピリミジン骨格を有する二座配位子である。Ｒ１は４〜６位および４’〜６’位の炭素原子に結合する炭素数１〜３のアルキル基である。ｅはＲ１の個数を示し、独立に０〜３の整数である。合成が容易であるという観点からｅは０〜１が好ましく、０がより好ましい。一方で、前述のとおり置換基とターピリジル基との相互作用による安定化の観点からは、Ｒ１が存在する場合はメチル基であることが好ましい。この場合、ｅは１〜２が好ましく、１がより好ましい。特に２，２’−ジピリミジンにおける６および６’位の炭素原子にＲ１が結合することが好ましい。 Ib is a bidentate ligand having a 2,2′-dipyrimidine skeleton. R 1 is an alkyl group having 1 to 3 carbon atoms bonded to 4 to 6-position and 4 ′ to 6′-position carbon atoms. e represents the number of R 1 and is an integer of 0 to 3 independently. From the viewpoint that synthesis is easy, e is preferably 0 to 1, and more preferably 0. On the other hand, as described above, from the viewpoint of stabilization due to the interaction between the substituent and the terpyridyl group, when R 1 is present, a methyl group is preferable. In this case, e is preferably 1 to 2, and more preferably 1. In particular, R 1 is preferably bonded to carbon atoms at the 6 and 6 ′ positions in 2,2′-dipyrimidine.
Ｉｃは１，１０−フェナントロリン骨格を有する二座配位子である。Ｒ１は２〜４位および７〜９位の炭素原子に結合する炭素数１〜３のアルキル基である。Ｒ２は５位および６位の炭素原子に結合する炭素数１〜３のアルキル基である。ｆはＲ１の個数を示し、独立に０〜３の整数である。ｇはＲ２の個数を示し、０〜２の整数である。合成が容易であるという観点からｆおよびｇは０〜１が好ましく、０がより好ましい。一方で、前述のとおり置換基とターピリジル基との相互作用による安定化の観点から、Ｒ１およびＲ２が存在する場合はメチル基であることが好ましい。この場合、ｆおよびｇは１〜２が好ましく、１がより好ましい。特に、１，１０−フェナントロリンにおける２および９位の炭素原子にＲ１が結合することが好ましい。 Ic is a bidentate ligand having a 1,10-phenanthroline skeleton. R 1 is an alkyl group having 1 to 3 carbon atoms bonded to the carbon atoms at the 2-4 and 7-9 positions. R 2 is an alkyl group having 1 to 3 carbon atoms bonded to the carbon atoms of the 5 and 6 positions. f shows the number of R 1 and is an integer of 0-3 independently. g represents the number of R 2, is an integer of 0-2. From the viewpoint of easy synthesis, f and g are preferably 0 to 1, and more preferably 0. On the other hand, as described above, from the viewpoint of stabilization due to the interaction between the substituent and the terpyridyl group, when R 1 and R 2 are present, a methyl group is preferable. In this case, f and g are preferably 1 to 2, and more preferably 1. In particular, R 1 is preferably bonded to the carbon atoms at the 2 and 9 positions in 1,10-phenanthroline.
Ｙ−ｎは、ｎ価のカウンターアニオンである。カウンターアニオンとは電荷バランスを取るために結合するアニオンである。ｎは１〜４の整数、ｍはｎ×ｍ＝４を満足する整数である。すなわち、Ｙが１価のアニオンである場合、ｍは４である。（Ｙ−ｎ）ｍは特に限定されず、通常錯体の分野で用いられるアニオンであればよいが、合成しやすいとの観点から、（ＰＦ６ −）４、（ＣｌＯ４ −）４、（ＢＦ４ −）４、または（ＰＰｈ４ −）４が好ましい。 Y- n is an n-valent counter anion. A counter anion is an anion that binds to balance the charge. n is an integer of 1 to 4, and m is an integer satisfying n × m = 4. That is, m is 4 when Y is a monovalent anion. (Y n ) m is not particularly limited, and may be any anion usually used in the field of complexes. From the viewpoint of easy synthesis, (PF 6 − ) 4 , (ClO 4 − ) 4 , (BF 4 -) 4 or, (PPh 4 -) 4 is preferred.
以下に特に好ましい金属錯体の二例を示す。 Two examples of particularly preferred metal complexes are shown below.
２．金属錯体の特性
（１）還元剤としての性質
本発明の金属錯体は、過酸化水素を発生させずに速やかに酸素を水へ還元しうる活性を有する。反応系によっても異なるが、本発明の金属錯体は非常に微量な量で酸素を還元できる。例えば、金属錯体の量は、１モルのＯ２に対して０．００５〜０．０２モルが好ましい。また還元反応は温和な条件で行なうことができ、１０〜３０℃の室温にて実施できる。反応における溶媒は、水または通常使用される有機溶媒のいずれを用いてもよい。
詳細は実施例に示すが、本発明の金属錯体は主として酸素の４電子還元反応（前述のスキーム１の反応）を進行させるので、過酸化水素を発生せずに酸素を水へと還元できる。この機序は限定されないが、下記スキームのように考えられる。
2. Properties of Metal Complex (1) Properties as a Reducing Agent The metal complex of the present invention has an activity capable of quickly reducing oxygen to water without generating hydrogen peroxide. Although depending on the reaction system, the metal complex of the present invention can reduce oxygen in a very small amount. For example, the amount of the metal complex is preferably 0.005 to 0.02 mol with respect to 1 mol of O 2 . The reduction reaction can be performed under mild conditions, and can be performed at a room temperature of 10 to 30 ° C. As the solvent in the reaction, either water or a commonly used organic solvent may be used.
Although details are shown in the examples, the metal complex of the present invention mainly proceeds with a four-electron reduction reaction of oxygen (the reaction of the above-mentioned scheme 1), so that oxygen can be reduced to water without generating hydrogen peroxide. Although this mechanism is not limited, it is considered as the following scheme.
まず、Ａで表されるCo(III)-O-O-Co(III)構造を有する金属錯体が１電子ずつ二段階の還元を受けてＢで表されるCo(II)-O-O-Co(II) 構造を有する金属錯体を生成する。次に、Co(II)-O-O-Co(II)が２電子の還元を受けると共にプロトン化し、O-O結合が切断されて、Ｃで表される金属錯体が形成される。金属錯体Ｃにおけるアクア配位子は酸素分子と置換されて水を生成し、金属錯体Ａが再生される。酸素の４電子還元反応は、架橋パーオキソCo-O-O-Co構造を経て進行するが、本発明の金属錯体は、この架橋パーオキソ構造を安定化させるため、４電子還元反応を選択的に進行させると考えられる。 First, a metal complex having a Co (III) -OO-Co (III) structure represented by A undergoes two-step reduction of one electron at a time, and Co (II) -OO-Co (II) represented by B A metal complex having a structure is produced. Next, Co (II) —O—O—Co (II) undergoes two-electron reduction and is protonated, and the O—O bond is cleaved to form a metal complex represented by C. The aqua ligand in the metal complex C is substituted with oxygen molecules to generate water, and the metal complex A is regenerated. The 4-electron reduction reaction of oxygen proceeds via a bridged peroxo Co—OO—Co structure, but the metal complex of the present invention stabilizes the bridged peroxo structure, and thus the 4-electron reduction reaction proceeds selectively. Conceivable.
（２）用途
本発明の金属錯体は、酸素還元反応の触媒として有用である。さらに本発明の金属錯体は水に不溶であるので、水系の酸素還元反応の触媒として特に好適であり、燃料電池のカソードに使用することができる。
(2) Use The metal complex of the present invention is useful as a catalyst for oxygen reduction reaction. Furthermore, since the metal complex of the present invention is insoluble in water, it is particularly suitable as a catalyst for an aqueous oxygen reduction reaction, and can be used for a cathode of a fuel cell.
３．金属錯体の製造方法
本発明の金属錯体は、
第１工程：一般式（１）で表される化合物と、ＣｏＳＯ４またはＦｅＳＯ４とを混合しながら加熱する工程、
第２工程：前記反応系に、酸素と、一般式（２ａ）、（２ｂ）、または（２ｃ）で表される化合物とを加え、加熱する工程、および
第３工程：前記反応系にＺｎ・Ｙ−ｎで表される塩（Ｚｎはｎ価のカチオンであり、Ｙおよびｎは前述のとおり定義される）を加える工程、を経て製造されることが好ましい。
3. Method for producing metal complex The metal complex of the present invention comprises:
First step: a compound represented by the general formula (1), heating with mixing and CoSO 4 or FeSO 4,
Second step: the reaction system, and oxygen, the formula (2a), and a compound represented by (2b), or (2c) is added, a step of heating, and the third step: Z n in the reaction system · Y -n represented salt (Z n is an n-valent cation, Y and n are as defined above) preferably is manufactured through a process, adding.
（１）第１工程
本工程で使用される一般式（１）で表される化合物（以下「化合物１」ともいう）は、下記の構造を有する。
(1) 1st process The compound (henceforth "compound 1") represented by General formula (1) used at this process has the following structure.
Ｒ２〜Ｒ７およびｈ〜ｌは前述のとおりである。
本工程では、化合物１と、ＣｏＳＯ４またはＦｅＳＯ４とを撹拌して混合しながら加熱する。化合物１とＣｏＳＯ４またはＦｅＳＯ４のモル比は１：１が好ましいが、ＣｏＳＯ４またはＦｅＳＯ４がやや過剰であってもよい。加熱する温度は５０〜１００℃が好ましい。特に、作業性の点から、エタノール等のアルコールを溶媒に用いて、その還流温度で加熱することが好ましい。本工程により、化合物１のターピリジル基部分が金属に配位した金属錯体が生成すると考えられる。
R 2 to R 7 and h to l are as described above.
In this step, the compound 1 and CoSO 4 or FeSO 4 are heated while being stirred and mixed. The molar ratio of compound 1 to CoSO 4 or FeSO 4 is preferably 1: 1, but CoSO 4 or FeSO 4 may be slightly excessive. The heating temperature is preferably 50 to 100 ° C. In particular, from the viewpoint of workability, it is preferable to use an alcohol such as ethanol as a solvent and heat at the reflux temperature. This step is thought to produce a metal complex in which the terpyridyl group portion of Compound 1 is coordinated to the metal.
化合物１は公知の方法で入手できる。例えば、非特許文献６（Wada, T.; Tsuge, K.; Tanaka, K., Inorg. Chem. 2001, 40, (2), 329-337）に記載の方法や、非特許文献７（Wada, T.; Muckerman, J. T.; Fujita, E.; Tanaka, K. Dalton Trans., 2011 40, 2225-2233）に記載の方法により合成できる。以下に非特許文献６および７に記載の合成方法の概要を述べる。
非特許文献６に記載の合成法は下記スキームで表される。
Compound 1 can be obtained by a known method. For example, the method described in Non-Patent Document 6 (Wada, T .; Tsuge, K .; Tanaka, K., Inorg. Chem. 2001, 40, (2), 329-337) or Non-Patent Document 7 (Wada , T .; Muckerman, JT; Fujita, E .; Tanaka, K. Dalton Trans., 2011 40, 2225-2233). The outline of the synthesis methods described in Non-Patent Documents 6 and 7 will be described below.
The synthesis method described in Non-Patent Document 6 is represented by the following scheme.
１）水酸化ナトリウム存在下、１，８−ジホルミルアントラセンと２−アセチルピリジンのエタノール／水（５０／５０）混合溶液を室温で３時間撹拌して１，８−ビス［３−（２−ピリジル）−３−オキソ−１−プロペニル］アントラセンＡを収率９６％で得る。
２）窒素下で、Ａと２５ｍｏｌ％のｔ−ＢｕＯＫの脱水ピリジン溶液に２−アセチルピリジンを加え、５０℃で８時間撹拌して１，８−ビス［１，５−ビス（２−ピリジル）−１，５−ジオキソ−３−ペンチル］アントラセンＢを得る。
３）溶媒を減圧留去した後、過剰量の酢酸アンモニウムとエタノールを加え、３時間加熱環流して淡黄色粉末を析出させる。この粉末を濾過した後、高速液体クロマトグラフィーで精製してｂｔｐｙａｎを得る（収率４０％）。
1) In the presence of sodium hydroxide, a mixed solution of 1,8-diformylanthracene and 2-acetylpyridine in ethanol / water (50/50) was stirred at room temperature for 3 hours, and 1,8-bis [3- (2- Pyridyl) -3-oxo-1-propenyl] anthracene A is obtained with a yield of 96%.
2) Add 2-acetylpyridine to a dehydrated pyridine solution of A and 25 mol% t-BuOK under nitrogen and stir at 50 ° C. for 8 hours to 1,8-bis [1,5-bis (2-pyridyl) -1,5-Dioxo-3-pentyl] anthracene B is obtained.
3) After distilling off the solvent under reduced pressure, an excess amount of ammonium acetate and ethanol are added and heated under reflux for 3 hours to precipitate a pale yellow powder. The powder is filtered and then purified by high performance liquid chromatography to obtain btpyan (yield 40%).
非特許文献７に記載の合成法は下記スキームで表される。 The synthesis method described in Non-Patent Document 7 is represented by the following scheme.
１）触媒として１ｍｏｌ％のＰｄ２（ｄｂａ）３（ｄｂａ＝ジベンジリデンアセトン）と２−ジシクロヘキシルホスフィノトリ（イソプロピルジフェニル）、塩基として酢酸ナトリウムを用い、これらの存在下で、１，８−ジクロロアントラセンとビス（ネオペンチルグリコシラト）ジボロンの１，４−ジオキサン溶液を９０℃で二日間、窒素下で加熱撹拌することにより、収率８８％で１，８−ビス（ネオペンチルグリコシラトボリル）アントラセンを得る。
２）ジエチルエーテル中で１，８−ビス（ネオペンチルグリコシラトボリル）アントラセンにジエタノールアミンを作用させることにより、収率７６％でアントラセニル−１，８−ジボロン酸を得る。
３）触媒として５ｍｏｌ％のＰｄ（ＰＰｈ３）４と塩基として炭酸ナトリウムを用い、これらの存在下で、アントラセニル−１，８−ジボロン酸と２当量の４’−トリフリル−２，２’：４’，２”−ターピリジンのＤＭＦ溶液を窒素下、１１０℃で２４時間加熱環撹拌して目的とするｂｔｐｙａｎ得る（収率６８％）。
1) 1 mol% Pd 2 (dba) 3 (dba = dibenzylideneacetone) and 2-dicyclohexylphosphinotri (isopropyldiphenyl) as catalyst and sodium acetate as base, in the presence of 1,8-dichloro A 1,4-dioxane solution of anthracene and bis (neopentylglycosilato) diboron is heated and stirred under nitrogen at 90 ° C. for 2 days, thereby yielding 1,8-bis (neopentylglycosilatoboryl) in 88% yield. Get anthracene.
2) Anthracenyl-1,8-diboronic acid is obtained in a yield of 76% by allowing diethanolamine to act on 1,8-bis (neopentylglycosilatoboryl) anthracene in diethyl ether.
3) 5 mol% Pd (PPh 3 ) 4 as catalyst and sodium carbonate as base, and in the presence of these, anthracenyl-1,8-diboronic acid and 2 equivalents of 4′-trifuryl-2,2 ′: 4 A DMF solution of ', 2 ″ -terpyridine is heated and stirred at 110 ° C. for 24 hours under nitrogen to obtain the desired btpyan (yield 68%).
上記は多環炭化水素基がアントラセンジイル基である場合を例にした説明であるが、多環炭化水素基がキサンテンジイル基である場合も同様に合成できる。例えば、非特許文献７の方法において、出発物質を４，５−ジブロモ−２，７−ジ−ｔ−ブチル−９，９−ジメチルキサンテンをすることにより、多環炭化水素基がキサンテンジイル基である化合物を合成できる。 The above is an example of the case where the polycyclic hydrocarbon group is an anthracenediyl group, but the synthesis can be similarly performed when the polycyclic hydrocarbon group is a xanthenediyl group. For example, in the method of Non-Patent Document 7, the starting material is 4,5-dibromo-2,7-di-t-butyl-9,9-dimethylxanthene, so that the polycyclic hydrocarbon group is a xanthenediyl group. A compound can be synthesized.
（２）第２工程
本工程では、前記反応系に、酸素と、一般式（２ａ）、（２ｂ）、または（２ｃ）で表される化合物とを加え、さらに加熱する。一般式（２ａ）、（２ｂ）、または（２ｃ）で表される化合物（以下「化合物２ａ」、「化合物２ｂ」、または「化合物２ｃ」ともいう）は以下の構造を有する。
(2) Second Step In this step, oxygen and a compound represented by the general formula (2a), (2b), or (2c) are added to the reaction system and further heated. The compound represented by the general formula (2a), (2b), or (2c) (hereinafter also referred to as “compound 2a”, “compound 2b”, or “compound 2c”) has the following structure.
Ｒ１、Ｒ２、およびｄ〜ｇは前述のとおりである。
以下、説明を簡単にするため、化合物２ａを使用する場合について説明する。化合物２ａ等の使用量は、化合物１：化合物２ａのモル比が１：１となる量が好ましいが、化合物２ａがやや過剰であってもよい。加熱する温度は５０〜１００℃が好ましい。特に、作業性の点から、エタノール等のアルコールを溶媒に用いて、その還流温度で加熱することが好ましい。
R 1 , R 2 , and d to g are as described above.
Hereinafter, in order to simplify the description, a case where the compound 2a is used will be described. The amount of compound 2a and the like used is preferably such that the molar ratio of compound 1 to compound 2a is 1: 1, but compound 2a may be slightly excessive. The heating temperature is preferably 50 to 100 ° C. In particular, from the viewpoint of workability, it is preferable to use an alcohol such as ethanol as a solvent and heat at the reflux temperature.
本工程においては反応系に酸素を加えるが、作業効率の観点から、酸素は、反応系へ酸素ガスを吹き込む、または空気を吹き込むことにより添加することが好ましい。酸素は、化合物１の量に対して過剰の量を吹き込むことが好ましい。本工程により、化合物１のターピリジル基部分と、化合物２ａとが金属に配位し、かつM-O-O-M構造を有する金属錯体が生成すると考えられる。 In this step, oxygen is added to the reaction system. From the viewpoint of work efficiency, oxygen is preferably added by blowing oxygen gas or air into the reaction system. Oxygen is preferably blown in an excess amount relative to the amount of compound 1. By this step, it is considered that the terpyridyl group portion of Compound 1 and Compound 2a are coordinated to the metal and a metal complex having an M—O—O—M structure is formed.
（３）第３工程
本工程では、前記反応系にＺｎ・Ｙ−ｎで表される塩を加える。Ｚｎはｎ価のカチオンであり、Ｙおよびｎは前述のとおりである。塩としては、通常当該分野で用いられる塩を使用できる。入手容易性等の観点から、Ｙ−ｎは、（ＰＦ６ −）４、（ＣｌＯ４ −）４、（ＢＦ４ −）４、または（ＰＰｈ４ −）４であることが好ましい。またＺｎは、ＮＨ４ ＋、Ｎａ＋、またはＫ＋であることが好ましい。塩は、得られる金属錯体に対して過剰量添加されることが好ましい。具体的には、化合物１：塩＝１：５０〜１：１００となる量が好ましい。本工程の温度は限定されないが、室温（１０〜３５℃）とすることが好ましい。
本工程により前述の式（Ｉ）で表される金属錯体が得られる。通常、金属錯体は析出物として得られるので、定法により単離および精製することが好ましい。
(3) Third Step This, added salt represented by Z n · Y -n to the reaction system. Z n is an n-valent cation, Y and n are as described above. As the salt, a salt usually used in the art can be used. From the viewpoint of availability and the like, Y n is preferably (PF 6 − ) 4 , (ClO 4 − ) 4 , (BF 4 − ) 4 , or (PPh 4 − ) 4 . Z n is preferably NH 4 + , Na + , or K + . The salt is preferably added in an excess amount relative to the resulting metal complex. Specifically, an amount of Compound 1: Salt = 1: 50 to 1: 100 is preferable. Although the temperature of this process is not limited, It is preferable to set it as room temperature (10-35 degreeC).
By this step, the metal complex represented by the aforementioned formula (I) is obtained. Usually, since a metal complex is obtained as a precipitate, it is preferably isolated and purified by a conventional method.
４．燃料電池用カソード
本発明の金属錯体は電極材料に担持させることにより、燃料電池のカソードとして使用できる。カソードとは酸素還元反応が生じる電極である。電極材料は限定されず、例えばカーボンペーパーやカーボンクロス等を使用できる。電極材料に金属錯体を担持させる方法も、公知の方法を用いることができる。
さらに、本発明の金属錯体を含むカソードと、公知のアノードおよび公知の電解質とを組合せて、燃料電池とすることができる。
4). Cathode for fuel cell The metal complex of the present invention can be used as a cathode of a fuel cell by being supported on an electrode material. The cathode is an electrode where an oxygen reduction reaction occurs. The electrode material is not limited, and for example, carbon paper or carbon cloth can be used. A known method can also be used as a method for supporting the metal complex on the electrode material.
Furthermore, a fuel cell can be obtained by combining a cathode containing the metal complex of the present invention with a known anode and a known electrolyte.
［実施例１］金属錯体１の合成
本例の反応スキームを以下に示す。
[Example 1] Synthesis of metal complex 1 The reaction scheme of this example is shown below.
４０ｍｇのＣｏＳＯ４（和光純薬株式会社製）と、５０ｍｇの１，８−ビス（２，２’：６’，２”−ターピリジル）アントラセン（以下「ｂｔｐｙａｎ」ともいう）と、７０ｍＬのエタノールと１０ｍＬの蒸留水の混合溶液を２００ｍＬフラスコに装入し、エタノール還流下で、１８時間撹拌した。ｂｔｐｙａｎは、非特許文献７（Wada, T.; Muckerman, J. T.; Fujita, E.; Tanaka, K. Dalton Trans., 2011 40, 2225-2233）に記載の方法で合成したものを用いた。
続いて、２４ｍｇの２，２’−ビピリジン（東京化成株式会社製）をフラスコ内に装入し、エアポンプを用いて空気をフラスコ内に吹き込みながら、エタノール還流下で、２４時間撹拌し反応を行なった。
ＮＨ４ＰＦ６（和光純薬株式会社製）の飽和水溶液３０ｍＬをフラスコ内に装入し、室温で撹拌し、フラスコ内に結晶粉末を得た。結晶をろ過した後、上記スキームに記載の金属錯体を得た。収率は４９％であった。
40 mg CoSO 4 (manufactured by Wako Pure Chemical Industries, Ltd.), 50 mg 1,8-bis (2,2 ′: 6 ′, 2 ″ -terpyridyl) anthracene (hereinafter also referred to as “btpyan”), 70 mL ethanol, A mixed solution of 10 mL of distilled water was charged into a 200 mL flask and stirred for 18 hours under ethanol reflux. The btpyan was synthesized by the method described in Non-Patent Document 7 (Wada, T .; Muckerman, JT; Fujita, E .; Tanaka, K. Dalton Trans., 2011 40, 2225-2233).
Subsequently, 24 mg of 2,2′-bipyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) was charged into the flask, and the reaction was carried out by stirring for 24 hours under ethanol reflux while blowing air into the flask using an air pump. It was.
30 mL of a saturated aqueous solution of NH 4 PF 6 (manufactured by Wako Pure Chemical Industries, Ltd.) was charged into the flask and stirred at room temperature to obtain a crystalline powder in the flask. After filtering the crystals, the metal complex described in the above scheme was obtained. The yield was 49%.
得られた金属錯体（以下、「金属錯体１」ともいう）について以下のとおり分析し、金属錯体が上記スキームに示す構造であることを確認した。
元素分析：株式会社ジェイサイエンスラボ製の有機微量元素分析装置（ＭＩＣＲＯＣＯＲＤＥＲ ＪＭ１０）を使用して行なった。結果を表１に示す。
The obtained metal complex (hereinafter also referred to as “metal complex 1”) was analyzed as follows to confirm that the metal complex had the structure shown in the above scheme.
Elemental analysis: An organic trace element analyzer (MICROCORDER JM10) manufactured by J Science Lab Co., Ltd. was used. The results are shown in Table 1.
ＩＲ：日本分光株式会社製の赤外分光計（ＦＴ／ＩＲ−４１００）を使用して、ＫＢｒ法により行なった。８６０ｃｍ−１と５５９ｃｍ−１にＰＦ６に由来するピークを確認した。
ＥＳＩ−ＭＳ分析：Ｗａｔｅｒｓ−Ｍｉｃｒｏｍａｓｓ社製の飛行時間型質量分析計（ＬＣＴ）を使用して行なった。３７５．６ｍ／ｚのピークが確認できた。このピークは、金属錯体イオン（４＋）の質量電荷比からＯ２の質量電荷比を除き、かつＨ２Ｏの質量電荷比を加えた質量電荷比である。
ＵＶ−ｖｉｓ：株式会社島津製作所製の紫外可視分光光度計（ＵＶ−１８００）を使用して、アセトニトリル溶媒を用いて行なった。以下のピークを確認した。
λｍａｘ＝３７０ｎｍ（ε＝８４６０ｃｍ−１Ｍ−１）
λｍａｘ＝４３８ｎｍ（ε＝４５３０ｃｍ−１Ｍ−１）
IR: Performed by KBr method using an infrared spectrometer (FT / IR-4100) manufactured by JASCO Corporation. It was confirmed the peak derived from the PF 6 to 860cm -1 and 559cm -1.
ESI-MS analysis: Performed using a time-of-flight mass spectrometer (LCT) manufactured by Waters-Micromass. A peak of 375.6 m / z was confirmed. This peak is a mass-to-charge ratio obtained by removing the mass-to-charge ratio of O 2 from the mass-to-charge ratio of the metal complex ion (4+) and adding the mass-to-charge ratio of H 2 O.
UV-vis: An ultraviolet-visible spectrophotometer (UV-1800) manufactured by Shimadzu Corporation was used and an acetonitrile solvent was used. The following peaks were confirmed.
λmax = 370nm (ε = 8460cm - 1M -1)
λmax = 438nm (ε = 4530cm - 1M -1)
［実施例２］回転リングディスク電極測定
回転リングディスク電極（ＢＡＳ社製、回転リングディスク電極装置（ＲＲＤＥ−３））を準備した。回転リングディスク電極は図２に示すように、ディスク電極（炭素電極）と、その外側に設けられたリング電極（白金電極）を有し、それぞれの電極に独立に電位を印加することができる。ディスク電極に酸素還元触媒を担持し、回転リングディスク電極を水に浸し、一定の速度でディスク電極を回転させながらディスク電極の電位を正側から負側へ掃引する。すると酸素還元反応が進行する。この反応において水の他に過酸化水素等の活性酸素種が生成すると活性酸素種は遠心力によりリング電極上に移動する。リング電極に＋０．６Ｖ（ｖｓ．ＳＣＥ）程度の電位をかけると活性酸素種のみが酸化されるので、リング電極に発生する電流値の量により、過酸化水素等と活性酸素種の生成量が測定できる。
[Example 2] Measurement of rotating ring disk electrode A rotating ring disk electrode (manufactured by BAS, rotating ring disk electrode device (RRDE-3)) was prepared. As shown in FIG. 2, the rotating ring disk electrode has a disk electrode (carbon electrode) and a ring electrode (platinum electrode) provided outside the disk electrode, and a potential can be applied to each electrode independently. An oxygen reduction catalyst is supported on the disk electrode, the rotating ring disk electrode is immersed in water, and the potential of the disk electrode is swept from the positive side to the negative side while rotating the disk electrode at a constant speed. Then, an oxygen reduction reaction proceeds. In this reaction, when active oxygen species such as hydrogen peroxide are generated in addition to water, the active oxygen species move onto the ring electrode by centrifugal force. When a potential of about +0.6 V (vs. SCE) is applied to the ring electrode, only the active oxygen species are oxidized. Therefore, depending on the amount of current generated in the ring electrode, the amount of hydrogen peroxide and the production of active oxygen species is reduced. It can be measured.
実施例１で得た金属錯体１（０．５ｍＭ）のアセトン溶液を調製した。回転リングディスク電極のディスク電極（直径４ｍｍ）の上に当該アセトン溶液５０μＬを塗布し、室温で自然乾燥させた。リン酸を用いてｐＨを１に調整した水を準備し、当該水に回転リングディスク電極を浸し、炭素電極の電位を＋０．６０Ｖから０Ｖ（ｖｓ．ＳＣＥ）まで掃引した。このときリング電極には＋０．６Ｖの電位を印加し、炭素電極を１，０００ｒｐｍで回転させた。結果を図３に示す。＋０．４Ｖよりも負側の電位においてディスク電極の電流値が増加し、酸素還元反応が進行したことが分かる。一方でリング電極の電流値の増加は観測されなかった。このことから、金属錯体１は過酸化水素等の活性酸素種を発生することなく１００％の選択性で水を生成することが分かった。 An acetone solution of metal complex 1 (0.5 mM) obtained in Example 1 was prepared. 50 μL of the acetone solution was applied on the disk electrode (diameter 4 mm) of the rotating ring disk electrode and allowed to dry naturally at room temperature. Water whose pH was adjusted to 1 using phosphoric acid was prepared, the rotating ring disk electrode was immersed in the water, and the potential of the carbon electrode was swept from +0.60 V to 0 V (vs. SCE). At this time, a potential of +0.6 V was applied to the ring electrode, and the carbon electrode was rotated at 1,000 rpm. The results are shown in FIG. It can be seen that the current value of the disk electrode increased at a potential on the negative side of +0.4 V, and the oxygen reduction reaction proceeded. On the other hand, no increase in the current value of the ring electrode was observed. From this, it was found that the metal complex 1 generates water with selectivity of 100% without generating active oxygen species such as hydrogen peroxide.
［実施例３］ターンオーバー数の測定
１．０×１０−８モルの金属錯体１を１０ｍＬのアセトンに溶解してアセトン溶液を調製した。４ｃｍ２の表面積を有する炭素電極（ＢＡＳ社製）の上に当該アセトン溶液１．０ｍＬを塗布し、室温で自然乾燥させた。対極として白金板（株式会社ニラコ社製）を準備した。これらの電極を１００ミリモル／Ｌの過塩素酸水溶液に浸し、０Ｖ（ｖｓ．ＳＣＥ）で定電位電解を行った。その結果、４８Ｃの電気量が消費された。金属錯体のターンオーバー数は１，２４３回であった。炭素電極上に塗布した金属錯体が徐々に解離してしまうため、ターンオーバー数は上記の値となったが、解離しなければ金属錯体の真のターンオーバー数はより高くなると考えられた。このように、ごく少量の金属錯体により効果的に酸素還元反応を触媒できることが明らかとなった。
Example 3 Measurement of Turnover Number 1.0 × 10 −8 mol of metal complex 1 was dissolved in 10 mL of acetone to prepare an acetone solution. The acetone solution 1.0mL was apply | coated on the carbon electrode (made by BAS) which has a surface area of 4 cm < 2 >, and was naturally dried at room temperature. A platinum plate (manufactured by Niraco Co., Ltd.) was prepared as a counter electrode. These electrodes were immersed in a 100 mmol / L perchloric acid aqueous solution and subjected to constant potential electrolysis at 0 V (vs. SCE). As a result, 48C of electricity was consumed. The turnover number of the metal complex was 1,243. Since the metal complex applied on the carbon electrode gradually dissociates, the turnover number becomes the above value, but the true turnover number of the metal complex is considered to be higher if it does not dissociate. Thus, it became clear that an oxygen reduction reaction can be effectively catalyzed by a very small amount of metal complex.
［実施例４］フェロセンを還元剤とした化学的な酸素還元反応
飽和状態にある酸素に対して過剰量のフェロセン（ＦｅＩＩＣｐ２）を還元剤に用いると、酸素の４電子還元反応が進行し、水が生成するとともに酸素の飽和濃度に対して４倍の濃度のフェロセニウム（ＦｅＩＩＩＣｐ２ ＋）が生成する（下記スキーム３）。酸素の２電子還元反応が進行して過酸化水素が生成した場合には２倍の濃度のフェロセニウムが生成する（下記スキーム４）。
[Example 4] Chemical oxygen reduction reaction using ferrocene as a reducing agent When an excessive amount of ferrocene (Fe II Cp 2 ) is used as a reducing agent with respect to oxygen in a saturated state, a four-electron reduction reaction of oxygen proceeds. In addition, water is generated and ferrocenium (Fe III Cp 2 + ) having a concentration four times the oxygen saturation concentration is generated (Scheme 3 below). When the two-electron reduction reaction of oxygen proceeds to produce hydrogen peroxide, twice the concentration of ferrocenium is produced (Scheme 4 below).
従って、生成したフェロセニウムの量を定量することによって、４電子還元反応、２電子還元反応のいずれが進行したかを特定できる。 Therefore, by quantifying the amount of ferrocenium produced, it is possible to specify which of the four-electron reduction reaction and the two-electron reduction reaction has proceeded.
本例では、ストップトフロー装置（ＵＮＩＳＯＫＵ社製、ＲＳＰ−１０００）を用い２２℃にて、フェロセンを還元剤とした化学的な酸素還元反応を行なった。具体的には、当該装置の密閉容器に、２０ミリモル／Ｌの過塩素酸で酸性にしたベンゾニトリルと、１００ミリモル／Ｌの表２に示した各種フェロセンと、２０マイクロモル／Ｌの実施例１で得た金属錯体１とを添加し反応を行ない、フェロセニウムの生成量を定量した。ベンゾニトリルの酸素飽和濃度は１．７ミリモル／Ｌであった。結果を表２に示す。 In this example, a chemical oxygen reduction reaction using ferrocene as a reducing agent was carried out at 22 ° C. using a stopped-flow apparatus (manufactured by UNISOKU, RSP-1000). Specifically, in a sealed container of the apparatus, benzonitrile acidified with 20 mmol / L perchloric acid, various ferrocenes shown in Table 2 at 100 mmol / L, and examples of 20 micromol / L. The metal complex 1 obtained in 1 was added and reacted to quantify the amount of ferrocenium produced. The oxygen saturation concentration of benzonitrile was 1.7 mmol / L. The results are shown in Table 2.
また、ＦｅＣｐ２（シクロペンタジエン環に置換基を持たないフェロセン）を用いた場合のＦｅＣｐ２ ２＋の濃度変化を図４に示す。図４から、２秒以内にフェロセニウム濃度はほぼ一定となり、反応が終結したことが分かる。ほぼ同様の実験条件下で前述の金属錯体（ｉｉ）および（ｉｉｉ）を触媒に用いた場合、１００〜６００秒程度の反応時間を要することが報告されている（非特許文献８：Fukuzumi, S.; Okamoto, K.; Gros, C. P.; Guilard, R. J. Am. Chem. Soc., 2004, 126, 10441-10449）。このことから、実施例１で得た金属錯体１は非常に高活性な触媒であることが分かる。ＦｅＣｐ２を用いた本例で生成したフェロセニウムの濃度は５．７ミリモル／Ｌであり、酸素１分子に対して３．３電子の還元を行ったことになる。つまり酸素の４電子還元反応が６５％、２電子還元反応が３５％の割合で進行することが明らかとなった。 FIG. 4 shows the change in the concentration of FeCp 2 2+ when FeCp 2 (ferrocene having no substituent in the cyclopentadiene ring) is used. FIG. 4 shows that the ferrocenium concentration became almost constant within 2 seconds, and the reaction was completed. It has been reported that when the above metal complexes (ii) and (iii) are used as catalysts under almost the same experimental conditions, a reaction time of about 100 to 600 seconds is required (Non-patent Document 8: Fukuzumi, S Okamoto, K .; Gros, CP; Guilard, RJ Am. Chem. Soc., 2004, 126, 10441-10449). This shows that the metal complex 1 obtained in Example 1 is a very high activity catalyst. The concentration of ferrocenium produced in this example using FeCp 2 was 5.7 mmol / L, which means that 3.3 electrons were reduced per molecule of oxygen. That is, it was revealed that the 4-electron reduction reaction of oxygen proceeds at a rate of 65% and the 2-electron reduction reaction at a rate of 35%.
一方、より還元電位が低いジメチルフェロセンやデカメチルフェロセンを用いると４電子還元反応の割合が増加した。このことから４電子と２電子の還元反応の割合は、還元剤の還元電位に依存することが明らかとなった。また、本発明の金属錯体の酸化還元電位（０．６０Ｖ）よりも正側の還元電位を有するフェロセン類（アセチルフェロセンとシアノフェロセン）では、反応は進行しなかった。 On the other hand, when dimethylferrocene or decamethylferrocene having a lower reduction potential was used, the ratio of the 4-electron reduction reaction increased. From this, it became clear that the ratio of the reduction reaction of 4 electrons and 2 electrons depends on the reduction potential of the reducing agent. In addition, the reaction did not proceed with ferrocenes (acetylferrocene and cyanoferrocene) having a reduction potential on the positive side of the redox potential (0.60 V) of the metal complex of the present invention.
［参考例１］
実施例１で得たCo-16O-16O-Co構造を有する金属錯体１をアセトニトリルに溶解して５ｍＭの溶液とし、当該溶液を測定用セルに装入し、室温にて、３６Ｏ２ガスをおおよそ３分間ほど吹き込んだ。この反応の前後におけるラマンスペクトル分析結果を図５に示す。図５に示すように、容易に３２Ｏと３６Ｏが置換して、Co-18O-18O-Co構造を有する金属錯体が生成した。さらにセルのふたを開けて空気に晒すとCo-16O-16O-Co構造を有する金属錯体が生成することを確認した。
[Reference Example 1]
The metal complex 1 having the Co- 16 O- 16 O-Co structure obtained in Example 1 was dissolved in acetonitrile to form a 5 mM solution, and the solution was charged into a measuring cell, and at room temperature, 36 O 2 Gas was blown in for about 3 minutes. FIG. 5 shows the results of Raman spectrum analysis before and after this reaction. As shown in FIG. 5, 32 O and 36 O were easily substituted to form a metal complex having a Co- 18 O- 18 O-Co structure. Furthermore, when the cell lid was opened and exposed to air, it was confirmed that a metal complex having a Co- 16 O- 16 O-Co structure was formed.
［実施例５］金属錯体５の合成
（１）２，７−ジ−ｔ−ブチル−９，９−ジメチルキサンテン−４，５−ジボロン酸の合成
１．０ｇ（２．１ｍｍｏｌ）の４，５−ジブロモ−２，７−ジーｔ−ブチル−９，９−ジメチルキサンテン（Ａｌｄｒｉｃｈ社製）を、滴下ロート、還流冷却器を備える１００ｍＬフラスコに装入した。窒素気流下で３０ｍＬの脱水ヘキサンを加えてフラスコ内を撹拌した。１．６ｍＬ（４．２ｍｍｏｌ）のｎ−ＢｕＬｉを少しずつフラスコ内に加えた後、室温で３．５時間撹拌し、さらに８５℃で１０分間還流した。室温まで冷却した後、フラスコを氷浴に漬け、２．０ｍＬ（４．２ｍｍｏｌ）のＢ（ＯＭｅ）３を撹拌しながらゆっくりと加えた。その後、フラスコ内の温度を室温にして、７０時間撹拌した。次いで、３．５ｍＬのＨＣｌ水溶液（ＨＣｌは０．２９ｍｍｏｌ）を加え、５．５時間撹拌した。溶液をろ過し、白色粉末を得た。当該粉末を２５ｍＬの水に懸濁させた後、過剰量のＮａＯＨ水溶液を加えた。さらに粉末をろ別し、ＨＣｌ水溶液で洗浄して白色粉末を得た。本工程のスキームおよび結果物のＮＭＲ分析結果を示す。
[Example 5] Synthesis of metal complex 5 (1) Synthesis of 2,7-di-t-butyl-9,9-dimethylxanthene-4,5-diboronic acid 1.0 g (2.1 mmol) of 4,5 -Dibromo-2,7-di-t-butyl-9,9-dimethylxanthene (manufactured by Aldrich) was charged into a 100 mL flask equipped with a dropping funnel and a reflux condenser. Under a nitrogen stream, 30 mL of dehydrated hexane was added and the inside of the flask was stirred. 1.6 mL (4.2 mmol) of n-BuLi was added to the flask little by little, and then stirred at room temperature for 3.5 hours and further refluxed at 85 ° C. for 10 minutes. After cooling to room temperature, the flask was immersed in an ice bath and 2.0 mL (4.2 mmol) of B (OMe) 3 was slowly added with stirring. Then, the temperature in the flask was brought to room temperature and stirred for 70 hours. Next, 3.5 mL of an aqueous HCl solution (HCl was 0.29 mmol) was added and stirred for 5.5 hours. The solution was filtered to obtain a white powder. The powder was suspended in 25 mL of water, and then an excess amount of aqueous NaOH solution was added. Further, the powder was filtered off and washed with an aqueous HCl solution to obtain a white powder. The scheme of this step and the NMR analysis result of the resulting product are shown.
（２）４，５−ビス（ターピリジル）−２，７−ジ−ｔ−ブチル−９，９−ジメチルキサンテン （ｂｔｐｙｘａ）の合成
本化合物は、非特許文献９および１０を参考に合成した。
非特許文献９：Aikawa, K.; Nagata, T. Inorg. Chim. Acta 2000, 306, 223-226
非特許文献１０：Okamura,R.; Wada,T.; Aikawa,K.; Nagata,T.; Tanaka,K., Inorg. Chem. (2004), 43(22), 7210-7217
９９．８ｍｇ（０．２４ｍｍｏｌ）の前工程で得た２，７−ジ−ｔ−ブチル−９，９−ジメチルキサンテン−４，５−ジボロン酸と、１９１．１ｍｇ（０．４９ｍｍｏｌ）のｔｅｒｐｙ−ＯＴｆと、２７．１ｍｇ（０．０２３ｍｍｏｌ）のＰｄ（ＰＰｈ３）４と、１０７．１ｍｇ（０．９９ｍｍｏｌ）のＮａ２ＣＯ３を、１００ｍＬのシュレンク管に装入した。内容物を減圧下にて６０℃で１時間撹拌した。内容物を室温まで冷却した後、反応容器内に窒素を導入した。反応器内に２０ｍＬの脱水ＤＭＦを添加し、容器内を減圧にした後に窒素を導入することを５回繰り返した。その後、窒素下で１１０℃にて２１時間撹拌した。フラスコ内の温度を室温にし、ロータリーエバポレーターを用いて溶媒を除去した。残留物に塩化メチレンを加えて、吸引ろ過して透明な黄色のろ液を得た。このろ液を、ロータリーエバポレーターを用いて乾燥し、固形分を得た。この固形分にヘキサンを加え吸引ろ過した。黄色粉末をろ別した。その後、ろ液に白色粉末が析出した。この白色粉末をろ別し、目的物を得た。終了は５８．８ｍｇ、収率は３０．６％であった。本反応のスキームと、ＮＭＲ分析結果を示す。
(2) Synthesis of 4,5-bis (terpyridyl) -2,7-di-t-butyl-9,9-dimethylxanthene (btpyxa) This compound was synthesized with reference to Non-Patent Documents 9 and 10.
Non-Patent Document 9: Aikawa, K .; Nagata, T. Inorg. Chim. Acta 2000, 306, 223-226
Non-Patent Document 10: Okamura, R .; Wada, T .; Aikawa, K .; Nagata, T .; Tanaka, K., Inorg. Chem. (2004), 43 (22), 7210-7217
99.8 mg (0.24 mmol) of 2,7-di-t-butyl-9,9-dimethylxanthene-4,5-diboronic acid obtained in the previous step and 191.1 mg (0.49 mmol) of terpoxy- OTf, 27.1 mg (0.023 mmol) of Pd (PPh 3 ) 4 and 107.1 mg (0.99 mmol) of Na 2 CO 3 were charged into a 100 mL Schlenk tube. The contents were stirred at 60 ° C. under reduced pressure for 1 hour. After the contents were cooled to room temperature, nitrogen was introduced into the reaction vessel. 20 mL of dehydrated DMF was added to the reactor, and the inside of the container was depressurized, and then nitrogen was introduced five times. Then, it stirred at 110 degreeC under nitrogen for 21 hours. The temperature in the flask was brought to room temperature, and the solvent was removed using a rotary evaporator. Methylene chloride was added to the residue, and suction filtration was performed to obtain a transparent yellow filtrate. This filtrate was dried using a rotary evaporator to obtain a solid content. Hexane was added to the solid content and suction filtration was performed. The yellow powder was filtered off. Thereafter, a white powder precipitated in the filtrate. The white powder was filtered off to obtain the desired product. The completion was 58.8 mg and the yield was 30.6%. The scheme of this reaction and the NMR analysis result are shown.
（３）金属錯体５の合成
５３．０ｍｇ（０．０６７ｍｍｏｌ）の前工程で得たｂｔｐｙｘａと、７０ｍＬのエタノールと、３８．９ｍｇ（０．１３８ｍｍｏｌ）のＣｏＳＯ４・７Ｈ２Ｏを１０ｍＬの蒸留水に溶解して得た水溶液とを、２００ｍＬのフラスコに装入し、１８時間加熱還流を行った。この時の溶液は透明な黄色であった。還流を停止し、フラスコ内に２１．５ｍｇ（０．１３８ｍｍｏｌ）のビピリジンを添加し、空気をバブリングしながら２４時間還流した。この時、溶液は赤色になった後に橙色になった。還流を停止し、フラスコ内に２０ｍＬの飽和ＮＨ４ＰＦ６水溶液を装入し、茶色粉末を析出させた。この粉末をろ別し、蒸留水とエーテルで洗浄した後、アセトン／エーテルで再結晶を行い、金属錯体（以下、「金属錯体５」ともいう）を茶色粉末として得た。収量は４７．６ｍｇ、収率は３８．６％であった。本反応のスキームと、ＮＭＲ分析結果を示す。
(3) Synthesis of Metal Complex 5 53.0 mg (0.067 mmol) of btpyza obtained in the previous step, 70 mL of ethanol, 38.9 mg (0.138 mmol) of CoSO 4 .7H 2 O in 10 mL of distilled water The aqueous solution obtained by dissolving in was charged into a 200 mL flask and heated to reflux for 18 hours. The solution at this time was clear yellow. The reflux was stopped, 21.5 mg (0.138 mmol) of bipyridine was added to the flask, and the mixture was refluxed for 24 hours while bubbling air. At this time, the solution turned red and then orange. Refluxing was stopped, and 20 mL of a saturated NH 4 PF 6 aqueous solution was charged into the flask to precipitate a brown powder. The powder was filtered, washed with distilled water and ether, and then recrystallized with acetone / ether to obtain a metal complex (hereinafter also referred to as “metal complex 5”) as a brown powder. The yield was 47.6 mg, and the yield was 38.6%. The scheme of this reaction and the NMR analysis result are shown.
実施例５で得た金属錯体５のＮＭＲスペクトル（ＤＭＳＯ溶媒）を図６に、ＩＲスペクトルを図７に示す。図７の８６０ｃｍ−１付近にＰ−Ｆ伸縮振動に由来するピークが観測された。このことから、ＰＦ６ −の存在が明らかである。 The NMR spectrum (DMSO solvent) of the metal complex 5 obtained in Example 5 is shown in FIG. 6, and the IR spectrum is shown in FIG. A peak derived from PF stretching vibration was observed near 860 cm −1 in FIG. From this, the presence of PF 6 − is clear.
［実施例６］サイクリックボルタンメトリー（ＣＶ）
作用電極にグラッシーカーボン電極、対電極に白金電極、参照電極にＡｇ／Ａｇ＋電極を使用して、実施例５で得た金属錯体５のＣＶを測定した。電解質として、３４０ｍｇの過塩素酸テトラブチルアンモニウムを１０ｍＬのベンゾニトリルに溶解して調製した０．１Ｍの電解質溶液を用いた。
まずＣＶセルに、５ｍＬの電解質溶液と撹拌子を入れ、ブランクでの測定を行った。次いで、６．３７ｍｇの金属錯体５をＣＶセルに入れ、アルゴン下と酸素下でそれぞれの測定を行った。さらに、ＣＶセルに０．２７ｍＬの６．６×１０−４Ｍの過塩素酸水溶液を加え、アルゴン下と酸素下でそれぞれの測定を行った。
[Example 6] Cyclic voltammetry (CV)
CV of the metal complex 5 obtained in Example 5 was measured using a glassy carbon electrode as a working electrode, a platinum electrode as a counter electrode, and an Ag / Ag + electrode as a reference electrode. As an electrolyte, a 0.1 M electrolyte solution prepared by dissolving 340 mg of tetrabutylammonium perchlorate in 10 mL of benzonitrile was used.
First, a 5 mL electrolyte solution and a stirrer were placed in a CV cell, and measurement was performed with a blank. Next, 6.37 mg of the metal complex 5 was put in a CV cell, and each measurement was performed under argon and oxygen. Furthermore, 0.27 mL of 6.6 × 10 −4 M perchloric acid aqueous solution was added to the CV cell, and each measurement was performed under argon and oxygen.
図８にアルゴン下での測定結果を示す。−０．３８Ｖおよび−０．７５Ｖに酸化還元波が観測された。それぞれのピークセパレーションは９６ｍＶ、１１４ｍＶであった。それぞれ、［ＣｏＩＩＩ，ＣＯＩＩＩ］４＋／［ＣｏＩＩＩ，ＣＯＩＩ］３＋、［ＣｏＩＩＩ，ＣＯＩＩ］３＋／［ＣｏＩＩ，ＣＯＩＩ］２＋の酸化還元反応に由来すると考えられる。 FIG. 8 shows the measurement results under argon. Redox waves were observed at -0.38V and -0.75V. The respective peak separations were 96 mV and 114 mV. It is thought to be derived from redox reactions of [Co III , CO III ] 4+ / [Co III , CO II ] 3+ , [Co III , CO II ] 3+ / [Co II , CO II ] 2+ , respectively.
酸素下では、−０．８Ｖ以下において還元波の増加が見られた。図９に、酸素下でかつ過塩素酸を加えた場合の測定結果を示す。＋０．３Ｖ以下で還元波の増加が見られた。このことから、実施例５で得た金属錯体５は、酸素還元を触媒することが明らかである。 Under oxygen, an increase in the reduction wave was observed at −0.8 V or less. FIG. 9 shows the measurement results when oxygen is added and perchloric acid is added. Reduction waves increased at +0.3 V or less. From this, it is clear that the metal complex 5 obtained in Example 5 catalyzes oxygen reduction.
［実施例７］フェロセンを還元剤とした化学的な酸素還元反応
金属錯体５を用い、実施例４と同様にしてフェロセンを還元剤とした化学的な酸素還元反応を行った。反応によって生じたフェロセニウムイオンの吸光度の変化を図１０に示す。この吸光度から、６．６ｍＭのフェロセニウムイオンが発生したことが明らかとなった。この濃度は、ベンゾニトリルの飽和酸素濃度１．７ｍＭの３．９倍である。よって、１つの酸素分子に対して３．９電子が還元されていることが明らかである。このことから、四電子還元が９５％、二電子還元が５％の割合で生じていることも明らかである。実施例１で得た金属錯体１では、４電子還元反応が６５％、２電子還元反応が３５％の割合で進行したことと比較すると、金属錯体５は４電子還元反応の選択性がより高いといえる。
[Example 7] Chemical oxygen reduction reaction using ferrocene as a reducing agent Using metal complex 5, a chemical oxygen reduction reaction using ferrocene as a reducing agent was performed in the same manner as in Example 4. FIG. 10 shows the change in absorbance of ferrocenium ions generated by the reaction. From this absorbance, it was revealed that 6.6 mM ferrocenium ions were generated. This concentration is 3.9 times the saturated oxygen concentration of benzonitrile of 1.7 mM. Therefore, it is clear that 3.9 electrons are reduced for one oxygen molecule. From this, it is also clear that four-electron reduction occurs at a rate of 95% and two-electron reduction occurs at a rate of 5%. In the metal complex 1 obtained in Example 1, the selectivity of the 4-electron reduction reaction is higher in the metal complex 5 than in the case where the 4-electron reduction reaction proceeds at a rate of 65% and the 2-electron reduction reaction at 35%. It can be said.
Claims (11)
Ｌは一般式（Ｉａ）、（Ｉｂ）、または（Ｉｃ）で表される二座配位子であり、
Ｘは炭素原子または酸素原子であり、
Ｒ３は独立に炭素数１〜４のアルキル基であり、Ｒ４〜Ｒ７は独立に炭素数１〜３のアルキル基であり、ｈは独立に０〜３の整数、ｉは０〜２の整数、ｊは独立に０〜４の整数、ｋは独立に０〜２の整数、ｌは独立に０〜４の整数であり、
Ｙ−ｎは、ｎ価のカウンターアニオンであり、ｎは１〜４の整数、ｍはｎ×ｍ＝４を満足する整数である。］ A metal complex represented by the general formula (I).
L is a bidentate ligand represented by the general formula (Ia), (Ib), or (Ic),
X is a carbon atom or an oxygen atom,
R 3 is independently an alkyl group having 1 to 4 carbon atoms, R 4 to R 7 are independently alkyl groups having 1 to 3 carbon atoms, h is independently an integer of 0 to 3, and i is 0 to 2 J is an integer of 0-4 independently, k is an integer of 0-2 independently, l is an integer of 0-4 independently,
Y −n is an n-valent counter anion, n is an integer of 1 to 4, and m is an integer that satisfies n × m = 4. ]
Ｒ ３ は独立に炭素数１〜４のアルキル基であり、Ｒ ４ 〜Ｒ ７ は独立に炭素数１〜３のアルキル基であり、ｈは独立に０〜３の整数、ｉは０〜２の整数、ｊは独立に０〜４の整数、ｋは独立に０〜２の整数、ｌは独立に０〜４の整数である。］
前記反応系に、酸素と、一般式（２ａ）、（２ｂ）、または（２ｃ）で表される化合物とを加え、加熱する工程、および
前記反応系にＺｎ・Ｙ−ｎで表される塩（Ｚｎはｎ価のカチオンであり、Ｙ −ｎ は、ｎ価のカウンターアニオンであり、ｎは１〜４の整数である）を加える工程、を含む、
請求項１〜７のいずれかに記載の金属錯体の製造方法。 A step of heating while mixing the compound represented by the general formula (1) and CoSO 4 or FeSO 4 ;
R 3 is independently an alkyl group having 1 to 4 carbon atoms, R 4 to R 7 are independently alkyl groups having 1 to 3 carbon atoms, h is independently an integer of 0 to 3, and i is 0 to 2 , J is independently an integer of 0 to 4, k is independently an integer of 0 to 2, and l is an integer of 0 to 4 independently. ]
Adding oxygen and a compound represented by the general formula (2a), (2b), or (2c) to the reaction system, and heating; and
The reaction system salt represented by Z n · Y -n (Z n is an n-valent cation, Y -n is an n-valent counter anion, n is an integer from 1 to 4) and Including the step of adding,
The manufacturing method of the metal complex in any one of Claims 1-7.
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