Photoassisted Oxidation of Sulfides Catalyzed by Artificial Metalloenzymes Using Water as an Oxygen Source

Abstract

Abstract:The Mn(TpCPP)-Xln10A artificial metalloenzyme, obtained by non-covalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into xylanase 10A from Streptomyces lividans (Xln10A) as a host protein, was found able to catalyze the selective photo-induced oxidation of organic substrates in the presence of [Ru II (bpy) 3 ] 2+ as a photosensitizer and [Co III (NH 3 ) 5 Cl] 2+ as a sacrificial electron acceptor, using water as oxygen atom source.

Photocatalytic Oxygenation Reactions Using Water and Dioxygen

“…[47] Av ariety of high-valent metal-oxo complexes were produced by ET oxidation of metal complexes by one-electron oxidants, such as [Ru(bpy) 3 ] 3 + and cerium(IV) ammonium nitrate (CAN), with H 2 O, catalyzing oxygenation of substrates by using H 2 Oa sa no xygen source. [35][36][37][38][39][40][41][42][43][44][45][46][47] [Ru(bpy) 3 ] 3 + was used as ao neelectron oxidant to produce high-valent metal-oxo complexes, but it can be replaced by much milder oxidants such as [Co III (NH 3 ) 5 Cl] 2 + under photoirradiation. [48][49][50][51][52][53][54][55][56][57][58] Scheme2 shows the catalytic cycle of the photocatalytic oxygenation of watersoluble substrates (S) with [Co III (NH 3 ) 5 Cl] 2 + as an oxidanta nd [Ru(bpy) 3 ] 2 + as ap hotocatalyst and am anganese(III)-hydroxo porphyrin ([(Por)Mn(OH)]) as an oxygenation catalyst.…”

“…[24][25][26][27][28][29][30][31][32][33][34] In such cases, oxygen in the high-valent metal-oxo species comes from O 2 ,w hich is the oxygen source in oxygenated products. [35][36][37][38][39][40][41][42][43][44][45][46] If metal-oxo speciesa re produced by photochemical oxidation of metal complexes with H 2 Ob y O 2 ,p hotocatalytic oxygenation of substrates with metal-oxo speciesw ould occur using H 2 Oa sa no xygen source andO 2 as an oxidant, both of which are the greenest availables pecies for such purposes. [35][36][37][38][39][40][41][42][43][44][45][46] If metal-oxo speciesa re produced by photochemical oxidation of metal complexes with H 2 Ob y O 2 ,p hotocatalytic oxygenation of substrates with metal-oxo speciesw ould occur using H 2 Oa sa no xygen source andO 2 as an oxidant, both of which are the greenest availables pecies for such purposes.…”

“…[47] Such preference of cyclohexene over styrene in the catalytic oxygenation has also been observedu nder photocatalytic oxygenation of other alkenes by porphyrins. [35][36][37][38][39][40][41][42][43][44][45][46][47] [Ru(bpy) 3 ] 3 + was used as ao neelectron oxidant to produce high-valent metal-oxo complexes, but it can be replaced by much milder oxidants such as [Co III (NH 3 ) 5 Cl] 2 + under photoirradiation. [47] Ethylbenzene was also hydroxylated to yield 1-phenylethanol using [47] The oxygen source in the oxygenatedp roducts was confirmed by using 18 Oi sotopic labeling to be H 2 O.…”

“…[24][25][26][27][28][29][30][31][32][33][34] High-valent metal-oxo speciesc an also be generated by the oxidation of metal complexesw ith H 2 O, when the oxygen atom in highvalent metal-oxo speciesc omes from H 2 O, as does that in the oxygenated products. [35][36][37][38][39][40][41][42][43][44][45][46] If metal-oxo speciesa re produced by photochemical oxidation of metal complexes with H 2 Ob y O 2 ,p hotocatalytic oxygenation of substrates with metal-oxo speciesw ould occur using H 2 Oa sa no xygen source andO 2 as an oxidant, both of which are the greenest availables pecies for such purposes.…”

Photoenzymes and Related Topics: An Update

“…Other P450 enzymes have also been engineered for photochemical syntheses . Moreover, other types of natural enzymes, such as xylanase , have been engineered into artificial photoenzymes. Natural photolyases do not photorepair crosslinks between bases on opposite DNA strands, but artificial systems that do have been constructed .…”