Bioinspired catalytic reactions with vitamin B12 derivative and photosensitizers

Abstract

As part of a study directed toward design of good catalytic systems based upon a hydrophobic vitamin B 12 , heptamethyl cobyrinate perchlorate, we describe the preparation of various nanomaterials using the vitamin B 12 derivative and photosensitizers. Examples include vitamin B 12 -hyperbranched polymers (HBPs), human serum albumin (HSA) containing vitamin B 12 derivatives, a vitamin B 12 -titanium dioxide hybrid catalyst, a vitamin B 12 -Ru complex combined system, and a vitamin B 12 -rose bengal combined system. These bioinspired materials have the potential as catalytic systems for the degradation of organic halide pollutants and for molecular transformations via radical intermediates during irradiation by UV or visible light, and offer a variety of applications that are of great interest in terms of green chemistry.

Significant enhancement of visible light photocatalytic activity of the hybrid B12-PIL/rGO in the presence of Ru(bpy)32+for DDT dehalogenation

“…It is well known that removing the second chlorine atom is much more difficult than the rst one from DDT molecules. According to the literature, for B 12 -based photocatalysts, B 12 -BVIm-Ru copolymer 7 and B 12 -HAS articial enzyme, 34 which are comparable to that used in this work, although they all showed enhanced photocatalytic activities with $100% conversion of DDT, few didechlorinated products were detected. From the above comparison, it can be concluded that the B 12 -PIL/rGO hybrid possessed very high photocatalytic activity for DDT dechlorination, especially for its didechlorination, in the presence of the photosensitizer Ru(bpy) 3 Cl 2 , and the introduction of rGO signicantly enhanced the reaction efficiency.…”

Vitamin B12 Enables Consecutive Generation of Acyl and Alkyl Radicals from One Reagent

“…Dechlorination is one of the biomimetic reactions catalysed by vitamin B 12 thus utilizing halogenated derivatives in B 12 -catalyzed reactions is often plagued by the formation of a significant amount of dehalogenated products. [34][35][36][37][38][39][40][41]50] In accordance, the reaction with thioester 8 possessing the chlorine substituent afforded desired product 14 in only 23 % yield in contrast to 64 % for the respective bromide. For substrates with more reactive benzyl substituents the competing dehalogenation predominated under optimized conditions, for thioester S-pyridin- 2-yl-3-(chloromethyl)benzothioate (11) product 22 formed in only 29 % yield, while substrate (10) with benzyl bromide moiety was entirely dehalogenated affording product 23.…”

The concept of photochemical enzyme models – State of the art

“…Based on the photosensitization of redoxactive B12 derivatives, Hisaeda and coworkers have recently developed various bio-inspired reactions for the degradation of organohalide pollutants such as DDT and related compounds according to eq. 3 under visible light exposure [79,80].…”