| 1. |
Hisashi Shimakoshi, Carbon Resource Recycling Reactions Mediated by Vitamin B12-TiO2 Hybrid Catalyst, ICPAC Bali 2023, 2023.09. |
| 2. |
Hisashi Shimakoshi, Bioinspired Catalysis in Electro- and Photo- Organic Syntheses, 日本化学会第１０３回春季年会, 2023.06. |
| 3. |
Hisashi Shimakoshi, Bioinspired Catalytic Reactions With and Beyond the Vitamin B12 Enzyme Function
, 11th Singapore International Chemistry Conference (SICC-11), 2022.12. |
| 4. |
Hisashi Shimakoshi, Catalytic Alkane Oxidations by Vitamin B12 Derivative as Homogeneous and Heterogeneous Catalyst, International Symposium on Organic Reactions (ISOR-15), 2022.11. |
| 5. |
Hisashi Shimakoshi, Bioinspired Catalytic Reactions With and Beyond the Vitamin B12 Enzyme Function, International Conference on Porphyrins and Phthalocyanines (ICPP), 2022.07. |
| 6. |
Hisashi Shimakoshi, Bioinspired Organic Reactions Learned from Vitamin B12 Dependent Enzymes, Organic Seminar at UCSB, 2020.12. |
| 7. |
Hisashi Shimakoshi, Fine Chemical Synthesis via Quinone Intermediate Using Catecholase Activity of Dicopper Complex, The 14th International Symposium on Organic Reactions, 2020.04. |
| 8. |
Hisashi Shimakoshi, Photo-driven B12 Inspired Reaction for Green Organic Synthesis, International Conference on Photocatalysis and Photoenergy 2019, 2019.05. |
| 9. |
Hisashi Shimakoshi, Bioorganometallic B12 as versatile Catalyst for Green Organic Synthesis, 9th International Symposium on Bioorganometallic Chemistry, 2019.07. |
| 10. |
Hisashi Shimakoshi, Yoshio Hisaeda, Bioinspired Photocatalyst for Green Molecular Transformation, 14th Korea-Japan Symposium on Frontier Photoscience-2018 , 2018.10, Recently, we have reported the unique catalysis of the cobalamin derivative (B12)-titanium oxide (TiO2) hybrid catalyst in which the B12 complex is immobilized on the surface of TiO2 and the B12 complex is reductively activated to form the CoI species by electron transfer from TiO2 under UV-light irradiation. The hybrid catalyst mediated the dehalogenation of various organic halides and was applied to the radical-mediated organic reaction via an alkylated complex as a catalytic intermediate. Though the great advantage of the catalyst is the facile and efficient formation of CoI species by light irradiation, UV light irradiation was required for band gap excitation of TiO2 semiconductor. To overcome this problem, we synthesized new B12-TiO2 hybrid catalyst composed of interfacial complexation with catechol. As a charge transfer band ascribed to catechol to TiO2 appear in visible region, this new hybrid catalyst is expected to work under visible light irradiation. Furthermore an oxygen switch for the catalysis of the B12-TiO2 hybrid catalyst has been developed. Oxygen-incorporated amide products were formed from the various trihalides by the B12-TiO2 hybrid catalyst. For the oxygen-incorporated reaction, carboxylic acid chloride was thought to be an intermediate.
. |
| 11. |
Hisashi Shimakoshi, Yoshio Hisaeda, Visible Light-Driven B12-TiO2 Hybrid Catalyst for Green Molecular Transformation, ISOR-13, 2018.11, Recently, we have reported the unique catalysis of the cobalamin derivative (B12)-titanium oxide (TiO2) hybrid catalyst in which the B12 complex is immobilized on the surface of TiO2 and the B12 complex is reductively activated to form the CoI species by electron transfer from TiO2 under UV-light irradiation. The hybrid catalyst mediated the dehalogenation of various organic halides and was applied to the radical-mediated organic reaction via an alkylated complex as a catalytic intermediate. Though the great advantage of the catalyst is the facile and efficient formation of CoI species by light irradiation, UV light irradiation was required for band gap excitation of TiO2 semiconductor. To overcome this problem, we synthesized new B12-TiO2 hybrid catalyst composed of interfacial complexation with catechol. As a charge transfer band ascribed to catechol to TiO2 appear in visible region,4 this new hybrid catalyst is expected to work under visible light irradiation. . |
| 12. |
Hisashi Shimakoshi, BIOORGANOMETALLIC B12 AS BIOINSPIRED CATALYST FOR GREEN ORGANIC SYNTHESIS , AsBiC-9, 2018.12, 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. The CoI species of B12 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. The applications of this intermediate for synthesis of fine chemicals were achieved in the field of synthetic organic chemistry. Furthermore, utilization of the CoI complex for proton reduction to form H2 was extensively studied. In these studies, Co-H complex is thought to be an intermediate for reactions. In this way, bioorganometallic B12 compounds are useful intermediates for organic synthesis. Therefore applications of the bioinspired intermediate, the Co-H complex, as well as biomimetic intermediate, the Co-C complex, have been developed for photochemical and electrochemical catalytic systems. For example, biomimetic isomerization and dechlorination efficiently proceeded. As for the bioinspired reaction, hydrogenation and hydrogen evolution were catalyzed by the B12 complex. If the suitable photosensitizer is selected for the photochemical system, a low energy visible light responsible catalytic system could be constructed, and utilization of clean and abundant sunlight for molecular transformation is realized. Here, we report the unique catalysis of bioorganometallic B12 for various green organic reactions.. |
| 13. |
Hisashi Shimakoshi, Bioorganometallic B12 as Versatile Catalyst for Green Organic Reaction, The 6th Asian-Pacific Congress on Ionic Liquid &Green Processes (APCIL-6), 2018.11, 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. The CoI species of B12 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. The applications of this intermediate for synthesis of fine chemicals were achieved in the field of green chemistry. Furthermore, utilization of the CoI complex for proton reduction to form H2 was extensively studied. In these studies, Co-H complex is thought to be an intermediate for reactions. These results prompted us to investigate application of B12 complex for new bio-inspired reaction. Here, we report the unique catalysis of the B12 hybrid catalyst for various green organic reactions.. |
| 14. |
Hisashi Shimakoshi, Yoshio Hisaeda, Light-Driven B12 Inspired Reactions toward Green Molecular Transformations, International Conference on Coordination Chemistry, 2018, 2018.07, 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.1 Here, we report the unique catalysis of the B12-semiconductor in which the B12 model complex is immobilized on TiO2. The semiconductor-metal complex composites become an effective photocatalyst for molecular transformations.2 Light driven B12-dependent enzymes mimic reactions, such as the dechlorination, the isomerization reactions catalytically proceeded by the B12-TiO2 (Fig. 1).3 Furthermore, the bioinspired reactions were also developed with the hybrid catalyst.4,5 The B12-TiO2 hybrid catalyst was used for the H2 evolution or alkenes reduction.. |
| 15. |
嶌越 恒,久枝良雄, Bioinspired Electrolysis by B12 Complex for Green Organic Synthesis, The 7th German-Japanese Symposium on Electrochemistry , 2017.09, The CoI species of B12(cobalamin) 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. The applications of this intermediate for synthesis of fine chemicals were achieved in the field of electroorganic chemistry. Furthermore, utilization of the CoI complex for proton reduction to form H2 was extensively studied. In these studies, Co-H complex is thought to be an intermediate for reactions. These results prompted us to investigate application of B12 complex for new bio-inspired reaction, and we succeed in development of various molecular transformations of alkenes by the B12 complex with electrochemical method.. |
| 16. |
嶌越 恒,久枝良雄, Hybrid Catalyst for Light-Driven Green Molecular Transformations, 13th Korea-Japan Symposium on Frontier Photoscience-2017, 2017.10, 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. These reactions are mediated by the alkylated cobalt complex which is generally formed by the reaction of the Co(I) state of the B12 with various electrophiles. We 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 various radical-mediated organic reactions. 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. For example, the B12-TiO2 could catalyze H2O reduction to form hydrogen.4 The cobalt-hydrogen complex (Co-H complex) was postulated to be the intermediate.. |
| 17. |
嶌越 恒, Green Catalysis of Hybrid Catalyst Composed of B12 Derivative and Semiconductor, IRCCS-JST Joint Symposium Base Metal Session , 2018.01, The semiconductor-metal complex composites become an effective photocatalyst for molecular transformations due to the synergistic effect by both components. Light-driven B12-dependent enzymes mimic reactions, such as the dechlorination of organic halide and the radical mediated isomerization reactions catalytically proceeded by the cobalamin (B12)-TiO2 hybrid catalyst. In addition to the enzyme mimic reaction, bioinspired reactions were developed with the hybrid catalyst. The B12-TiO2 hybrid catalyst was used for the H2 evolution or alkenes reduction.3,4 The multidisciplinary concept for the design of a hybrid catalyst will be reported.. |
| 18. |
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.. |
| 19. |
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.. |
| 20. |
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.. |
| 21. |
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.. |
| 22. |
嶌越 恒, Bioinspired Catalyst: Lessons from Vitamin B12 Enzymes, SPIRITS in Kyoto, 2016.02. |
| 23. |
嶌越 恒, Bio-inspired Catalysis of Functionalized Nanoparticle with Vitamin B12 Enzyme Function, SPIRITS Symposium , 2015.12. |
| 24. |
嶌越 恒, 久枝良雄, Light-Driven B12-TiO2 Hybrid Catalyst for Green Molecular Transformation, The 11th Korea-Japan Symposium on Frontier Photoscience, 2015.06. |
| 25. |
嶌越 恒, 米村俊介, 久枝良雄, Visible Light Responsive B12-TiO2 Hybrid Catalyst Composed of Interfacial Complexation, 227th ECS Meeting, 2015.05. |
| 26. |
嶌越 恒, 久枝 良雄, B12-TiO2 Hybrid Catalyst for Light-Driven Molecular Transformations, International Symposium on Bioorganometallic Chemistry, 2014.07. |
| 27. |
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.. |
| 28. |
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.
. |
| 29. |
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.. |
| 30. |
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. |
| 31. |
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. |
| 32. |
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. |
| 33. |
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. |
| 34. |
嶌越 恒, 久枝 良雄, Bioinspired Dehalogenation with Eco-Friendly Method, The 20th Asian Conference on Analytical Science, 2013.08. |
| 35. |
Shimakoshi Hisashi, 久枝 良雄, Photocatalytic Function of Vitamin B12 Complex with Photosensitizer, 7th Asian Photochemistry Conference, 2012.11. |
| 36. |
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. |
| 37. |
Shimakoshi Hisashi, 久枝 良雄, Oxidative Dechlorination of Chlorinated Organic Compound Catalyzed by Vitamin B12-TiO2, PRiME 2012, 2012.10. |
| 38. |
Shimakoshi Hisashi, Electrocatalytic Hydrogen Production Catalyzed by Dicobalt Complex with Imine/Oxime Ligand, 221st ECS Meeting, 2012.05. |
| 39. |
Cataltsis of vitamin b12 derivative in ionic liquid was reported.. |
| 40. |
Photosensitization property of brominated porphycene was reported.. |
| 41. |
Hydrogen evolution and reduction of various alkenes catalyzed by B12-TiO2 under UV light irradiation were investigated.. |
| 42. |
Hydrogen evolution and molecular transformation catalyzed by B12-TiO2 hybrid catalyst were reported.. |
| 43. |
Catalysis of tetrapyrrole compound in inoic liquid was reported.. |
| 44. |
Hydrogen evolution and alkene reduction catalyzed by B12-TiO2 were reported.. |
| 45. |
The light-driven B12 molecular transformation such as dechlorination of DDT was reported.. |
| 46. |
Hybrid catalyst composed by metal complex and TiO2 were reported. The hybrid catalyst showed high efficiency for hydrogen evolution and alkene reduction.. |
| 47. |
Hydrogen evolution and molecular transformation catalyzed by B12-TiO2 were investigated.. |
| 48. |
The hybrid polymer was synthesized by a radical polymerization and its photocatalytic reaction was investigated.. |
| 49. |
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.. |
| 50. |
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.. |
| 51. |
Photosensitizing property of several porphycenes was investigated.. |
| 52. |
Synthesis and property of hybrid catalyst composed of B12-hyperbranched polymer was reported.. |
| 53. |
Brominated porphycenes have been synthesized and it's crystal structure were determined by X-ray. Photophysical parameters was also determined.. |
| 54. |
Photophysical and photochemical properties of brominated porphycenes was investigated.. |
| 55. |
B12-TiO2 hybrid catalyst was prepared. The structure and properties of the hybrid catalyst was investigated by several methods.. |
| 56. |
Studies on Porphycene as Photosensitizer. |
