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Catecholase activity of Mannich-based dinuclear CuII complexes with theoretical modeling: New insight into the solvent role in the catalytic cycle
R SANYAL, P KUNDU, G ZHIGULIN, B GHOSH, S K CHATTOPADHYAY, E ZANGRANDO, D DAS
Published in Royal Society of Chemistry
2016
Volume: 40
   
Issue: 8
Pages: 6623 - 6635
Abstract
Four new dinuclear CuII complexes were synthesised from two Mannich-base ligands namely 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-chlorophenol (HL1) and 2-[bis(2-methoxyethyl)aminomethyl]-4-chlorophenol (HL2): [Cu2(L1)(OH)](ClO4)2·CH3OH (1), [Cu2(L2)2](ClO4)2·H2O (2), [Cu2(L2)2(NO3)2] (3) and [Cu2(L2)2(OAc)2]·H2O (4) and well characterised. X-ray diffraction analysis of the complexes reveals a Cu⋯Cu distance of 2.9183(13), 2.9604(6), 3.0278(4) and 3.0569(11) Å, respectively. In 1 the metal coordination geometry is intermediate between trigonal bipyramidal (TBP) and square pyramidal (SP) (τ = 0.488), in 2 the geometry is TBP (0.828 and 0.639) and in 3 and 4 is SP (τ = 0.188 and 0.083, respectively). Spectrophotometric investigations to evaluate the catecholase activity of complexes against 3,5-di-tert-butylcatechol (3,5-DTBC) and tetrachlorocatechol (TCC) in three different solvents (acetonitrile, methanol and DMSO) under completely aerobic conditions reveal that complexes 1-4 are able to oxidise 3,5-DTBC in all the solvents, while TCC can be oxidised only in acetonitrile (kcat = 0.0002-0.02 s-1). Intensive DFT calculations prove an ionic pathway for 1-3 while a unique neutral catalytic cycle for 4. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2016.
About the journal
JournalData powered by TypesetNew Journal of Chemistry
PublisherData powered by TypesetRoyal Society of Chemistry
ISSN1144-0546