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A visible light responsive catalytic system with the B12 complex as the catalyst and [Ir(dtbbpy)(ppy)2]PF6 as the photosensitizer was developed. It provides a convenient and efficient way to synthesize amides. Based on this method, trichlorinated organic compounds were converted into amides in the presence of an amine under aerobic conditions at room temperature in a one‐pot procedure. Various trichlorinated organic compounds and an amine source, such as primary, secondary, and cyclic amines, have been evaluated for this transformation, providing the expected products in moderate to excellent yields. Notably, product formation depended on the reaction atmosphere where the amide was obtained under aerobic conditions while partially dechlorinated products were obtained under anaerobic conditions. As this protocol is free from hazardous reagents, extra additives, noble metals, and dangerous gas, the present method provides a novel and efficient approach for amide synthesis under mild and easily controlled conditions. I see the light: A visible light responsive catalytic system with the B12 complex as the catalyst and [Ir(dtbbpy)(ppy)2]PF6 as the photosensitizer has been developed, and provides a convenient and efficient method for amide formation under air at room temperature. This protocol is free from hazardous reagents, extra additives, noble metals as well as dangerous gas and was applied to a wide range of trichlorinated organic compounds as the substrate to form a variety of amides (see figure). [ABSTRACT FROM AUTHOR]

A visible light induced three-component catalytic system with the cobalamin derivative (B12) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF3)ppy}2(dtbpy)]PF6) as a photosensitizer and triethanolamine as an electron source under N2 was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)3]Cl2 as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B12, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B12 enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway. [ABSTRACT FROM AUTHOR]

This Minireview is focused on the development of hybrid catalysts composed of photosensitizers and a metal complex, especially vitamin B12 derivatives. The semiconductor-metal complex composites are effective photocatalysts for molecular transformations due to the synergistic effect between the two components. The design of a B12 complex for the hybridization with TiO2 was simple and straightforward-cobyrinic acid, having seven carboxylic groups derived from naturally occurring B12 is stably immobilized on the TiO2. By using the hybrid catalysts as mimics of B12-dependent enzymes, light-driven reactions such as the dechlorination of organic halide pollutants, and radical-mediated isomerization proceeded catalytically. In addition to the enzyme-mimicking reactions, bioinspired reactions were also developed with the hybrid catalyst. The B12-TiO2 hybrid catalyst was used for hydrogen evolution and alkene reduction by UV light irradiation, and the cobalt-hydrogen complex (Co-H complex) was considered to be a putative intermediate of the reactions. The multidisciplinary concept for the design of a hybrid catalyst is described in this Minireview. [ABSTRACT FROM AUTHOR]

2,3,6,7,12,13,16,17-Octaethylhemiporphycenato Sn(IV) chloride, [SnIV(OEHPc)Cl2], and 2,3,6,7,12,13,16,17-octaethylporphycenato Sn(IV) chloride, [SnIV(OEPc)Cl2], were synthesized in high yields and fully characterized by various spectroscopic methods. The X-ray crystal structures of the Sn(IV) complexes with porphycene and hemiporphycene were determined for the first time. The photophysical and photochemical properties of the singlet state of the Sn(IV) porphycene and hemiporphycene complexes, structural isomers of porphyrin, have been investigated by fluorescence and phosphorescence spectroscopies. The relatively strong emission and long fluorescence lifetime of the Sn(IV) porphycene complexes indicated by the fluorescence quantum yield and lifetime measurement were observed in the case of the Sn(IV) porphycene ([SnIV(OEPc)Cl2], ΦF = 0.125, τs = 2681 ps; [SnIV(OEP)Cl2], ΦF = 0.010, τs = 438 ps; [SnIV(OEHPc)Cl2], ΦF = 0.027, τs = 733 ps). The triplet state of the Sn(IV) complexes was investigated by transient absorption spectroscopy. It became clear that the triplet lifetime of the Sn(IV) porphycene (tT = 49.9 μs) was longer when compared to those of the Sn(IV) porphyrin (τT = 32.6 μs) and hemiporphycene complexes (τT = 28.3 μs). These porphyrin isomer Sn(IV) complexes showed the high singlet oxygen generating ability, and the photo-oxidation of the 1,5-hydroxynaphthalene mediated by the Sn(IV) porphycene was the most effective among the complexes. This result is due to its more effective light absorption in the visible region and indicated that the porphycene is an excellent candidate as a photosensitizer. [ABSTRACT FROM AUTHOR]

Abstract: Porphycene was covalently immobilized in a sol–gel silica film deposited on a glass plate, and the immobilized porphycene showed a photosensitizing property with recycling for the photo-oxidation of 1,5-dihydroxynaphthalene. [Copyright &y& Elsevier]

A cobalamin derivative, heptamethyl cobyrinate perchlorate, was activated by UV light irradiation to form a Co(i) species in the presence of triethanolamine and used for a dechlorination reaction, and this photochemical reaction was accelerated in an ionic liquid. [ABSTRACT FROM AUTHOR]

The photophysical properties and photooxidation ability of the β-sulfonatoporphycenes are reported. The photophysical parameters depend on the number of substitutions. The disulfonated porphycene 2 is expected to be a new photosensitizer due to its high catalytic activity and photostability. [ABSTRACT FROM AUTHOR]