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Hisashi Shimakoshi Last modified date:2018.02.07

Associate Professor / Artificial Enzyme Chemistry
Department of Applied Chemistry
Faculty of Engineering

Graduate School
Undergraduate School
Administration Post

Academic Degree
Doctor of Engineering
Field of Specialization
Syntheses of functional compounds based on coordination chemistry
Research Interests
  • Development for Bioinspired Electrolysis
    keyword : vitamin B12, Clean reaction, electroorganic reaction, organic halide
    2015.04~2018.03VitaminB12 modified electrode was prepared by sol-gelmethod. Degradation of chlorinated organic compounds was performed by the modified electrode..
  • Development for clean molecular transformation by light irradiation
    keyword : photocatalyst molecular transformation
  • Formation of fine chemicals from environmental pollutant
    keyword : Electroorganic synthesis
  • Formation of fine chemicals from environmental pollutant
    keyword : Electroorganic synthesis
  • Development for clean molecular transformation
    keyword : photocatalyst molecular transformation
  • Preparation of Energy producing catalyst
    keyword : Photoreaction, Metal enzyme, Hybrid
  • Preaparation of hybrid catalyst
    keyword : Hybrid catalyst
    2007.04~2009.12Hybrid catalyst will be prepared and its catalytic reactivity will be evaluated..
  • Synthesis and property of porphycene complex
    keyword : porphycene, metal complex, spin state, redox behavior
    1998.04~2003.12Metal complex of porphycene, which is structural isomer of porphyrin was synthesized..
  • Synthesis of redox-switchable metal complex
    keyword : redox, stimulus, structural chnage
    2001.10~2003.12Redox changeable supramolecular complex have been synthesized..
  • Molecular transformation of organometallic compound
    keyword : cobalt-carbon bond, molecular transforamation
    1996.04~2003.12Molecular transformation of organic compounds was carried out by alkylated cobalt complexes..
  • Electroorganic reaction by B12 modified electrode
    keyword : vitamin B12, modified electrode, electroorganic reaction, organic halide
    2000.09~2003.12VitaminB12 modified electrode was prepared by sol-gelmethod. Degradation of chlorinated organic compounds was performed by the modified electrode..
Current and Past Project
  • Development for Green Photocatalyst
  • Studies on oxidation and reduction of metal ion
  • Studies on oxidation and reduction of metal ion
  • Studies on oxidation and reduction of metal ion
Academic Activities
1. Yoshio Hisaeda, Hisashi Shimakoshi, The Hnadbook of Porphyrin Science, World Scientific, Vol. 10, pp313-370, 2010.09.
1. Practical application of metal complex-photocatalyst hybrid for organic synthesis.
2. Vitamin B12-dependent enzymes, involving the cobalamin as a catalytic center, mediate various reactions. The Co(I) species of cobalamin is a supernucleophile and reacts with an alkyl halide to form an alkylated complex with dehalogenation. The alkylated complex is a useful reagent for forming radical species as the cobalt-carbon bond is cleaved homolytically by thermolysis, electrolysis and photolysis. In order to use vitamin B12 derivatives as green catalysts, development of B12 catalytic reaction to photosensitizer hybrid system have been carried out. And a novel hybrid catalyst constructed with cobalamin derivative and titanium oxide was also presented. Application of these B12 hybrid catalyst for several molecular transformations such as dechlorination of organic halides, coupling reaction, and 1,2-migration reaction of functional groups was reported..
1. Shimakoshi Hisashi, Yoshio Hisaeda, Hybrid Catalyst for Light-Driven Green Molecular Transformations, ChemPlusChem, 10.1002/cplu.201600303, 82, 18-29, 2016.10, This review is focused on the development of a hybrid catalyst composed of photosensitizers and a metal complex, especially B12 derivatives. The semiconductor-metal complex composites become an effective photocatalyst for molecular transformations due to the synergistic effect by both components. As a design of the B12 complex for the hybridization with TiO2, cobyrinic acid having seven carboxyric groups derived from naturally-occurring B12 was a simple and straightforward compound, which stably immobilized on the TiO2. By using the hybrid catalysts, light driven B12-dependent enzymes mimic reactions, such as the dechlorination of organic halide pollutants, and the radical mediated isomerization reactions catalytically proceeded. In addition to the enzyme mimic reaction, bioinspired reactions were also developed with the hybrid catalyst. The B12-TiO2 hybrid catalyst was used for the hydrogen evolution or alkenes reduction by UV light irradiation, and the cobalt-hydrogen complex (Co-H complex) was considered as a putative intermediate of the reactions. The multidisciplinary concept for the design of a hybrid catalyst is described in this review..
2. Shimakoshi Hisashi, Zhongli Luo, Yoshio Hisaeda, Electrolysis of Trichloromethylated Organic Compounds under Aerobic Condition Catalyzed by B12 Model Complex for Ester and Amide Formations, Dalton Trans., 10.1039/c6dt00556j, 45, 10173-10180, 2016.04, Electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of B12 model complex, heptamethyl cobyrinate perchlorate (1), in ethanol under aerobic condition using undivided cell equipped with platinum mesh cathode and zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. Corresponding esters were obtained when the electrolysis were carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for ester formation. While electrolysis was carried out under anaerobic condition, dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms) were obtained instead of ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides such as substituted benzotrichlorides were shown. Furthermore, formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by 1 in the presence of amines in acetonitrile were reported..
3. Shimakoshi Hisashi, Yoshio Hisaeda, Oxygen-Controlled Catalysis by Vitamin B12-TiO2: Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation, Angew. Chem. Int. Ed., 10.1002/anie.201507782, 54, 15439-15443, 2015.10.
4. Shimakoshi Hisashi, Yoko Nagami, Yoshio Hisaeda, Crystal Structure Dependence for Reactivities of B12-TiO2 Hybrid Catalysts with Anatase and Rutile Forms, Rapid Communication in Photoscience/Korea Photoscience Society, 10.5857/RCP.2015.4.1.9, 4, 1, 9-11, 2015.05.
5. Shimakoshi Hisashi, Hisaeda Yoshio, A polymerized ionic liquid-supported B12 catalyst with a ruthenium trisbipyridine photosensitizer for photocatalytic dechlorination in ionic liquids, Royal Society of Chemistry, 10.1039/c4dt01360c, 43, 13972-13978, 2014.08, A visible light-driven photocatalyst by immobilizing a B12 complex and a Ru(II) trisbipyridine photosensitizer in a polymerized ionic liquid (PIL) was developed. The synthesized copolymer was characterized by GPC, DLS, and its UV-vis absorption spectra and luminescence spectra. The Ru(II) trisbipyridine photosensitizer in the copolymer showed an enhanced emission compared to that of the monomer in the ionic liquid, 1-butyl-4-methylimidazolium bis(trifluoromethanesulfonly)amide ([C4mim][NTf2]). Formation of the Co(I) species of the B12 complex in the copolymer was confirmed by the UV-vis spectral change in [C4mim][NTf2] containing a sacrificial reductant (triethanolamine) during irradiation with visible light. The copolymer showed a high photocatalytic activity in various ionic liquids for the 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) dechlorination with ~99% conversion after a 2 h visible light irradiation. Furthermore, both the B12 catalyst and the photosensitizer in the polymer were easily recycled for use with the ionic liquid solvent without any loss of catalytic activity..
6. Shimakoshi Hisashi, Hisaeda Yoshio, B12-TiO2 Hybrid Catalyst for Light-Driven Hydrogen Production and Hydrogenation of C-C Multiple Bonds, ChemPlusChem, 10.1002/cplu.201402081, 79, 1250-1253, 2014.06, The B12-TiO2 hybrid catalyst mediated the H2O reduction to form hydrogen under UV light irradiation (1 turnover number per hour). The catalyst also mediated alkene reductions, such as styrene derivatives and alkylacrylates (maximum 100 turnover number per hour), under mild conditions; i.e., room temperature, ordinary pressure, and water or alcohol solvent..
7. Yoshio Hisaeda, 田原圭志朗, Hisashi Shimakoshi, Bioinspired Catalytic Reactions with Vitamin B12 Derivative and Photosensitizers, Pure and Applied Chemistry, 85, 1415-1426, 2013.08.
8. M Fujitsuka, Shimakoshi Hisashi, H Tei, M Noda, S Tojo, Hisaeda Yoshio, T Majima, Photoinduced electron transfer in supramolecular donor-acceptor dyads of Zn corrphycene, Physical Chemistry Chemical Physics, 39, 5677-5683, 2013.02.
9. Toru Okawara, Abe Masaaki, Shimakoshi Hisashi, Hisaeda Yoshio, A Pd(II)-hydroxyporphycene: Synthesis, characterization, and photoinduced proton-coupled electron transfer, Research on Chemical Intermediates, 39, 161-176, 2013.01.
10. Hisashi Shimakoshi, K. Sasaki, Y. Iseki, Yoshio Hisaeda, Synthesis and Photosensitizing Properties of Porphycene with Imidazolium Tag, J. Por. Phthalocyanines, 16, 530-536, 2013.01.
11. H. Shimakoshi, L. Li, M. Nishi, Y. Hisaeda, Photosensitizing Catalysis of B12 Complex without Additional Photosensitizer, Chem. Commun., 47, 10921, 2012.05.
12. Toru Okawara, Abe Masaaki, Koichi Hashimoto, Shimakoshi Hisashi, Hisaeda Yoshio, Hydrogenation effects in metalloporphycenes: synthesis and redox behavior of Ni(II)-tetra(n-propyl)dihydroporphycene, Chem. Commun., 47, 10921, 2012.05.
13. K. Tahara, H. Shimakoshi, A. Tanaka, Y. Hisaeda, Redox Behavior and Electrochemical Catalytic Function of B12-Hyperbranched Polymer, Bull. Chem. Soc. Jpn, 83, 1439-1446, 2011.12.
14. K. Tahara, Y. Chen, L. Pan, T. Masuko, H. Shimakoshi, Y. Hisaeda, Electrochemical Catalytic Carbon-Skeleton Rearrangement mediated by Imine/oxime-type B12 Model Complex, Chem. Lett., 40, 177-179, 2011.05.
15. H. Shimakoshi, M. Nishi, A. Tanaka, K. Chikama, Y. Hisaeda, Photocatalytic Function of Polymer-Supported B12 Complex with Ruthenium Trisbipyridine Photosensitizer, Chem. Commun., 47, 6548, 2011.05.
16. Hisashi Shimakoshi, Makoto Abiru, Keita Kuroiwa, Nobuo Kimizuka, Midori Watanabe Yoshio Hisaeda, Preparation and Reactivity of B12-TiO2 Hybrid Catalyst Immobilized on Glass Plate, Bull. Chem. Soc. Jpn, 83, 170-172, 2011.04.
17. Hisashi Shimakoshi, Daisuke Maeda, Yoshio Hisaeda, Supramolecular Assemblies of Crown-substituted Dinickel and Dicobalt Complexes with Guest Cation Binding, Supramolecular Chemistry, 23, 1-2, 131-139, 2011.01.
18. S. Izumi, H. Shimakoshi, M. Abe, Y. Hisaeda, Photo-Induced Ring-Expansion Reactions Mediated by B12-TiO2 Hybrid Catalyst B12-Hyperbranched Polymer, Dalton Trans, 39, 3302-3307, 2010.02.
19. H. Shimakoshi, M. Abiru, K. Kuroiwa, N. Kimizuka, M. Watanabe, Y. Hisaeda, Preparation and Reactivity of B12-TiO2 Hybrid Catalyst Immobilized on Glass Plate, Bull. Chem. Soc. Jpn, 83, 170-172, 2010.01.
20. D. Maeda, H. Shimakoshi, M. Abe, M. Fujitsuka, T. Majima, Y. Hisaeda , Synthesis of a Novel Sn(IV) Porphycene-Ferrocene Triad Linked by Axial Coordination and Solvent Polarity Effect in Photoinduced Charge Separation Process, Inorg. Chem, 49, 2872-2880, 2010.01.
21. Hisashi Shimakoshi, Masashi Nishi, Akihiro Tanaka, Katsumi, Chikama, Yoshio Hisaeda, Synthesis and Catalysis of B12-Core-Shell Hyperbranched Polymer, Chemistry Letters, 39, 22-23, 2010.01.
22. H. Shimakoshi, M. Abiru, S. Izumi, Y. Hisaeda, Green Molecular Transformation by a B12-TiO2 Hybrid Catalyst as an Alternative to Tributyltin Hydride, Chem. Commun, 6427-6429 , 2009.12.
23. H. Shimakoshi, E. Sakumori, K. Kaneko, Y. Hisaeda, B12-TiO2 Hybrid Catalyst for Dehalogenation of Organic Halides, Chem. Lett, 38, 468-469 , 2009.05.
24. H. Shimakoshi, K. Shibata, Y. Hisaeda , Molecular Recognition of Redox-Switchable Bis-crown Moieties Assembled on Dicobalt Complex., Inorg. Chem, 48, 1045-1052 , 2009.05.
25. Emiko Sakumori, Kenji Kaneko, Yoshio Hisaeda, B12-TiO2 Hybrid Catalyst for Dehalogenation of Organic Halides, Chemistry Letters, Vol. 38, No. 5, 468-469, 2009, 2009.04.
26. Hisashi Shimakoshi, Tatsushi Baba, Yuseuke Iseki, Ayataka Endo, Chihaya Adachi, Midori Watanabe, Yoshio Hisaeda, Photosensitizing properties of the porphycene immobilized in sol-gel derived silica coating films, Tetrahedron Letters, 49, 6198-6201, 2008.07.
27. Keishiro Tahara, Hisashi Shimakoshi, Akihiro Tanaka, Yohsio Hisaeda, Synthesis and characterization of vitamin B12-hyperbranched polymer, Tetrahedron Letters, 48, 5065-5068,2007, 2007.07.
28. Hisashi Shimakoshi, T. Takemoto, Isao Aritome, Yoshio Hisaeda, Redox-Switchable Molecular Containers Consisting of Dicobalt Complexes, Inorganic Chemistry, 10.1021/ic051482o, 44, 25, 9134-9136, 2005, 44, 9134-9136, 2005.11.
29. Hisashi Shimakoshi, Takayuki Kai, Isao Aritome, Yoshio Hisaeda, Syntheses of large-membered macrocycles having multipule hydrogen bondmoieties, Tetrahedron Letters, 10.1016/S0040-4039(02)02022-1, 43, 46, 8261-8264, 43, 8261-8264, 2003.01.
30. Hisahi Shimakoshi, Aki Nakazato, Mami Tokunaga, Kiyofumi Katagiri, Katsuhiko Ariga, Junichi Kikuchi, Yoshio Hisaeda, Hydrophobic vitamin B12 part 18. Preparation of a sol-gel modified electrode trapped with a vitamin B12 derivative and its photoelectrochemical reactivity, Dalton Transactions, 10.1039/b212863b, 11, 2308-2312, 2308-2312, 2003.01.
31. Hisashi Shimakoshi, Takeshi Kaieda, Takashi Matsuo, Hideaki, Sato, Yoshio Hisaeda, Syntheses of new water-soluble dicobalt complexes having two cobalt-carbon bonds and their ability for DNA cleavage, Tetrahedron Letters, 10.1016/S0040-4039(03)01252-8, 44, 28, 5197-5199, 44, 5197-5199, 2003.01.
32. Hisashi Shimakoshi, Masaomi Koga, Yoshio Hisaeda, Synthesis, characterization, and redox behavior of new dicobalt complexes having monoanionic imine/oxime-type ligands, Bulletin of the Chemical Society of Japan, 10.1246/bcsj.75.1553, 75, 7, 1553-1558, 75, 7, 1553-1558, 2002.07.
33. Hisashi Shimakoshi Aki Nakazato, Takashi Hayashi, Yoshimitsu Tachi, Yoshinori Naruta, Yoshio Hisaeda, Electroorganic syntheses of macrocycliclactonesmediated by vitamin B12 model complexes, Journal of Electroanalytical Chemistry, 10.1016/S0022-0728(01)00418-1, 507, 1-2, 170-176, 507, 170-176, 2001.07.
34. Hisashi Shimakoshi, Wataru Ninomiya, Yoshio Hisaeda, Reductive coupling of benzyl bromide catalyzed by a novel dicobalt complex having two salen units, Dalton Transaction, 10.1039/b010022f, 13, 1971-1974, 13, 1971-1974, 2001.06.
35. Hisashi Shimakoshi, Masaomi Koga, Takashi Hayashi, Yoshimitsu Tachi, Yoshinori Naruta, Yoshio Hisaeda, Formation and cleavage of a dicobalt complex bridged with a pentamethylene group, Chemistry Letters, 10.1246/cl.2001.346, 4, 346-347, 4, 346-347, 2001.04.
36. Hisashi Shimakoshi, Akihiro Goto, Yoshimitsu Tachi, Yoshinori Naruta, Yoshio Hisaeda, Synthesis and redox behavior of dialkylated dicobalt complexes having two discrete salen units, Tetrahedron Letters, 10.1016/S0040-4039(01)00040-5, 42, 10, 1949-1951, 42, 1949-1951, 2001.03.
37. Masahito Kodera, Hisashi Shimakoshi, Yoshimitsu Tachi, Kou Katayama, Koji Kano, Efficient oxidation of various phenols catalyzed by di-mu-hydroxo-dicopper(II) complexes of a hexapyridine dinucleating ligand, Chemistry Letters, 5, 441-442, 1998.05.
38. Masahito Kodera, Hisashi Shimakoshi, Koji Kano, First example of a rigid (mu-oxo-bis-mu-acetato)diiron(III) complex with 1,2-bis[2-di(2-pyridyl)methyl-6-pyridyl]ethane; itsefficient catalysis for functionalization of alkanes, Chemical Communications, 13, 1737-1738, 1996.11.
39. Hisashi Shimakoshi, Mami Tokunaga, Keita Kuroiwa, Nobuo Hisaeda, Preparation and electrochemical behavior of hydrophobic vitamin B12 covalently immobilized onto platinum electrode, Chemical Communications, 50-51.
1. 嶌越 恒, Bioinspired Catalysts Composed ofCobalamin Derivative and Semiconductor, International Symposium on Bioorganometallic Chemistry, 2016.09, I reported the unique catalysis of the B12-semiconductor such as TiO2 in which the B12 complex is immobilized on the surface of TiO2, and the B12 complex is reductively activated to form the Co(I) species by electron transfer from TiO2 under light irradiation. The hybrid catalyst mediated the dehalogenation of various organic halides and was applied to the radical-mediated organic reaction.2a This property also prompted us to investigate further applications of the B12-TiO2 catalyst utilizing the high reactivity of the Co(I) species of the B12 complex. The B12-TiO2 could catalyze H2O reduction to form hydrogen and the hydrogenation of C-C multiple bonds..
2. 嶌越 恒, Bioinspired Photocatalysts with Vitamin B12 Enzyme Function, The 12th Korea-Japan Symposium on Frontier Photoscience, 2016.04, Here, new visible light-driven photocataltic system composed of a B12 model complex and a Ru(bpy)32+ photosensitizer in a polymerized ionic liquid (PIL) was reported. The copolymer showed a high photocatalytic activity for the 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) dechlorination with visible light irradiation. Both the B12 catalyst and the photosensitizer in the polymer were easily recycled for use with the ionic liquid solvent without any loss of catalytic activity. Furthermore, a new bimetal MOF was synthesized by the solvothermal method. The cationic Ru(bpy)32+ photosensitizer and B12 model complex are easy to immobilize into the MOF by cation exchange reactions. The B12-Ru@MOF hybrid material worked as a heterogeneous catalyst and was recycled for the catalytic reaction. This is the first example of B12 catalysis using the MOF system..
3. 嶌越 恒, Carbon-Carbon Multiple Bond Reduction by B12-TiO2 Hybrid Catalyst, The 6th German-Japanese Symposium on Electrochemistry, 2016.04, I reported the new catalysis of the B12-TiO2 for alkene reduction. Cobalt-hydride complex is thought to be an intermediate for the reaction which could be formed by the reaction of Co(I) and a proton. An application of the B12-TiO2 catalyst for the hydrogenation of various alkenes and alkenes were reported..
4. 嶌越 恒, Unique Catalysis of Hybrid Catalysts with B12 Derivatives and Semiconductor, 8th Asian Biological Inorganic Chemistry Conference, 2016.12, Naturally-occurring B12(cobalamin)-dependent enzymes catalyze various molecular transformations that are of particular interest from the viewpoint of biological chemistry as well as synthetic organic chemistry and catalytic chemistry. The Co(I) species of B12 derivative is widely known as a supernucleophile that forms an alkylated complex by reaction with an alkyl halide. The alkylated complex is a useful reagent for forming radical species as the cobalt-carbon bond is readily cleaved homolytically by photolysis. Recently, application of CoI complex for proton reduction was extensively studied and electrochemical hydrogen evolutions by cobalt complex have been reported. In these studies, Co-H complex is thought to be an intermediate for hydrogen evolution. These results prompted us to investigate application of cobalamin derivative for new bio-isnpired reaction. Scope of substrate, detailed reaction mechanism, comparison to catalysis of other cobalt complex were reported..
5. 嶌越 恒, Bioinspired Catalyst: Lessons from Vitamin B12 Enzymes, SPIRITS in Kyoto, 2016.02.
6. 嶌越 恒, Bio-inspired Catalysis of Functionalized Nanoparticle with Vitamin B12 Enzyme Function, SPIRITS Symposium , 2015.12.
7. 嶌越 恒, 久枝 良雄, B12-TiO2 Hybrid Catalyst for Light-Driven Molecular Transformations, International Symposium on Bioorganometallic Chemistry, 2014.07.
8. 嶌越 恒, Applications of a Polymerized Ionic Liquid for Photocatalyst with
Vitamin B12 Function
, 錯体化学会第64回討論会, 2014.09, Vitamin B12 derivatives have been used as excellent catalysts in the dehalogenation reaction since the Co(I) species of vitamin B12 derivatives are supernucleophiles and can react with an alkyl halide to form an alkylated complex with dehalogenation. The ability of vitamin B12 derivatives to achieve reductive dehalogenations prompted us to investigate the catalysis of a vitamin B12 derivative not only for the degradation of various halogenated organic compounds but also for establishing a more efficient and eco-friendly catalytic system. Here, a polymerized ionic liquid-supported vitamin B12 derivative with a Ru(II) trisbipyridine photosensitizer was synthesized by radical polymerization. This hybrid polymer showed high solubilities in many kinds of ionic liquids and possessed unique photophysical and photocatalytic properties in an ionic liquid with an enhanced photoluminescence, high photocatalytic activity and recycled use for DDT dechlorination. Furthermore, we recently succeeded to achieve ionic liquid mediated photosensitizing reaction where ionic liquid was used as solvent and mediator. Detail of these photosensitized B12 reaction with ionic liquid play significant role were presented..
9. 嶌越 恒, 久枝 良雄, Heavy-atom Effect on Porphyrin Isomers, The 10th Korea-Japan Symposium on Frontier Photoscience, 2014.06, Inspired by the significance of the porphyrins, a new research direction has emerged that is devoted to the preparation and study of non-porphyrin tetrapyrrolic macrocycles. In the course of this study, a variety of porphyrin isomers such as porphycene, hemiporphycene, and corphycene were synthesized. Among them, porphycene, a structural isomer of porphyrin, was first synthesized by E. Vogel and coworkers in 1986. This isomer exhibits geometries of the N4 core shapes, which deviate from the ideal square shape of the porphyrin core, and this unique structural property results in the interesting electronic structure of the porphycene. Previously, we synthesized bromines substituted porphycenes (number of Br=1~4) and their photophysical and photochemical properties were investigated.5 A heavy atom, bromine, directly substituted into the porphycene macrocycles promote intersystem crossing by way of spin-orbit coupling. As a consequence, the singlet oxygen production ability via energy transfer from the triplet state of the brominated porphycene was enhanced. Furthermore, bromine substituent afforded many advantages for photochemical reactions, not only to enhance the rate of intersystem crossing but also robust enough for oxidation of the sensitizer itself and bathochromic shift of its absorption due to its electron withdrawing nature. To understand the heavy atom effect of bromine on the porphyrin isomers, we newly synthesized brominated hemiporphycene. Comparison of the structural and photophysical properties of brominated porphyrin isomers, porphycene, hemiporphycene, and porphyrin was investigated in this study.
The brominated hemiporphycene was synthesized from precursor hemiporphycene having vacant site by reaction with Br2. A brominated porphyrin (Br-TPP) was also synthesized according to literature.6 These compounds were identified by NMR, MS, UV-vis, and X-ray analyses. The quantum yields of the singlet oxygen generation (ΦΔ) by porphyrin isomers were determined by the phosphorescence at 1270 nm in air-saturated solutions.
The Q-type absorption band is red-shifted while the fluorescence intensity decreased with substitution of bromine on hemiporphycene. These behaviors are similar to those of porphycene we reported before,5 and the rate of intersystem crossing would be expected to become greater in the hemiporphycene. Actually, the ΦΔ value for hemiporphycene increased with substitution of bromine as shown in Figure 2. Interestingly, porphycene skeleton showed largest effect for the ΦΔ value by bromine substituent among the porphyrin isomers. The effect of bromine substituent on pyrrole ring in porphyrin isomers will be discussed.
10. 嶌越 恒, 久枝 良雄, Electrolysis of Trichlomethylated Compounds under Aerobic Condition Catalyzed by B12 Model Complex, 225st ECS Meeting, 2014.05, Electrolysis of Trichlomethylated Compounds under Aerobic Condition Catalyzed by B12 Model Complex was reported. Mechanism for this reaction was investigated..
11. 嶌越 恒, 久枝 良雄, Functionalization of Titanium Oxide by Metal Complex Modification and its Application to Energy and Molecular Transformation, 日本化学会第94春季年会アジア国際シンポジウム, 2014.03.
12. 嶌越 恒, 米村俊佑, 久枝 良雄, Vitamin B12-TiO2 Hybrid Catalyst for Green Molecular Transformation, The 9th Korea-Japan Symposium on Frontier Photoscience, 2013.11.
13. 嶌越 恒, 久枝 良雄, Oxygen Switch in Catalysis of Vitamin B12-TiO2 with Green Reaction, The International Symposium on Organic Reaction, 2013.11.
14. 米村俊佑, 嶌越 恒, 久枝 良雄, Visible Light Driven Bioisnpired Catalyst with B12 Function, 1st International Symposium on Chemical Energy Conversion Processes, 2013.06.
15. 嶌越 恒, 久枝 良雄, Bioinspired Dehalogenation with Eco-Friendly Method, The 20th Asian Conference on Analytical Science, 2013.08.
16. Shimakoshi Hisashi, 久枝 良雄, Photocatalytic Function of Vitamin B12 Complex with Photosensitizer, 7th Asian Photochemistry Conference, 2012.11.
17. Shimakoshi Hisashi, 久枝 良雄, ビタミンB12-酸化チタン複合触媒によるトリハロメタン類の酸化的脱塩素化反応, 第36回有機電子移動化学討論会, 2012.06.
18. Shimakoshi Hisashi, 久枝 良雄, Oxidative Dechlorination of Chlorinated Organic Compound Catalyzed by Vitamin B12-TiO2, PRiME 2012, 2012.10.
19. Shimakoshi Hisashi, Electrocatalytic Hydrogen Production Catalyzed by Dicobalt Complex with Imine/Oxime Ligand, 221st ECS Meeting, 2012.05.
20. Cataltsis of vitamin b12 derivative in ionic liquid was reported..
21. Photosensitization property of brominated porphycene was reported..
22. Hydrogen evolution and reduction of various alkenes catalyzed by B12-TiO2 under UV light irradiation were investigated..
23. Hydrogen evolution and molecular transformation catalyzed by B12-TiO2 hybrid catalyst were reported..
24. Catalysis of tetrapyrrole compound in inoic liquid was reported..
25. Hydrogen evolution and alkene reduction catalyzed by B12-TiO2 were reported..
26. The light-driven B12 molecular transformation such as dechlorination of DDT was reported..
27. Hybrid catalyst composed by metal complex and TiO2 were reported. The hybrid catalyst showed high efficiency for hydrogen evolution and alkene reduction..
28. Hydrogen evolution and molecular transformation catalyzed by B12-TiO2 were investigated..
29. The hybrid polymer was synthesized by a radical polymerization and its photocatalytic reaction was investigated..
30. Recycled use of a porphycene having an ionic liquid tag in photosensitising oxidation of various substrate was achieved using an ionic liquid as reaction medium..
31. B12-dependent enzymes, involving the cobalamin as a catalytic center, mediate various reactions.1 The CoI species of cobalamin derivative is widely known as a supernucleophile that forms an alkylated complex by reaction with an alkyl halide.2 The alkylated complex is a useful reagent for forming radical species as the cobalt-carbon bond is readily cleaved homolytically by photolysis, electrolysis, and thermolysis.3 Our research interest is focused on the application of this catalytic system to various molecular transformations. Recently, we reported dechlorination of DDT catalyzed by B12 derivative, heptamethyl cobrinate perchlorate, with a visible light irradiation system containing a [Ru(II)(bpy) 3]Cl2 photosensitizer as shown in Scheme 1.4 Although B12 derivative showed high catalytic efficiency in the reaction, large amount of photosensitizer was required for the reaction. To improve this problem, we synthesized new B12 catalyst having Ru(bpy)3 unit at peripheral position as shown in Chart 1. In this complex, photosensitizing unit was covalently bounded in cobalamin derivative, and which may allows efficient electron transfer from Ru(bpy)3 moiety to cobalt center of B12 moiety..
32. Photosensitizing property of several porphycenes was investigated..
33. Synthesis and property of hybrid catalyst composed of B12-hyperbranched polymer was reported..
34. Brominated porphycenes have been synthesized and it's crystal structure were determined by X-ray. Photophysical parameters was also determined..
35. Photophysical and photochemical properties of brominated porphycenes was investigated..
36. B12-TiO2 hybrid catalyst was prepared. The structure and properties of the hybrid catalyst was investigated by several methods..
37. Studies on Porphycene as Photosensitizer.
Membership in Academic Society
  • The Japanese Photochemistry Association
  • Very nice paper.
Other Educational Activities
  • 2010.09.