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Catalytic Conversion of Monophenols to Ortho ‐Quinones in a Tyrosinase‐Like Fashion: Towards More Biomimetic and More Efficient Model Systems
Author(s) -
Schottenheim Julia,
Fateeva Natalie,
Thimm Wulf,
Krahmer Jan,
Tuczek Felix
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300065
Subject(s) - tyrosinase , chemistry , catalysis , imine , quinone , ligand (biochemistry) , benzimidazole , semiquinone , stereochemistry , copper , electron transfer , aryl , photochemistry , combinatorial chemistry , organic chemistry , enzyme , receptor , biochemistry , alkyl
A new tyrosinase model based on the mononuclear copper(I) complex CuL bzm 1 is synthesized and characterized. The ligand L bzm 1 of this system contains a combination of an imine and a benzimidazole function which renders the system more biomimetic in comparison to the recently published L py 1 model of tyrosinase (M. Rolff, J. Schottenheim, G. Peters, F. Tuczek, Angew. Chem. Int. Ed. 2010 , 122 , 6583). As shown by UV/Vis and NMR spectroscopy, the CuL bzm 1 complex catalytically mediates the conversion of the monophenol DTBP‐H to the o ‐quinone DTBQ with a TON of 31. This reaction was also conducted in a stoichiometric fashion to get information about the involved intermediates and identify possible reasons for the observed increase in catalytic performance with respect to the L py 1 system. DFT calculations were performed for the μ‐catecholato dicopper intermediate, compound 4 bzm . These calculations indicate a mixed valent Cu I ‐semiquinone‐Cu II structure, indicating that one‐electron transfer from the monohydroxylated substrate to the copper centers has already occurred at this stage.