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Less Symmetrical Dicopper( II ) Complexes as Catechol Oxidase Models—An Adjacent Thioether Group Increases Catecholase Activity
Author(s) -
Merkel Michael,
Möller Niclas,
Piacenza Manuel,
Grimme Stefan,
Rompel Annette,
Krebs Bernt
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400768
Subject(s) - thioether , chemistry , catechol , copper , denticity , ligand (biochemistry) , medicinal chemistry , piperazine , stereochemistry , phenol , methylene , metal , square pyramidal molecular geometry , heteroatom , organic chemistry , ring (chemistry) , receptor , biochemistry
Three new unsymmetrical compartmental dinucleating ligands, 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(1‐piperidyl)ethyl}aminomethyl]phenol (HL1), 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(morpholin‐4‐yl)ethyl}aminomethyl]phenol (HL2), and 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(thiomorpholin‐4‐yl)ethyl}aminomethyl]phenol (HL3), have been synthesized in order to model the active site of type 3 copper proteins. The dicopper( II ) complexes of these ligands give first hints about the influence of a thioether group close to the metal site. The bromophenol‐based ligands have one piperazine arm and one other bidentate arm in positions 2 and 6 of the phenolic ring, respectively. With each ligand a dinuclear copper( II ) complex was prepared and structurally characterized. The copper ions were found to have square pyramidal environments and a mixture of endogenous phenoxo and exogenous acetate bridging. The influence of a heteroatom in one arm of the ligand on catecholase activity and speciation in solution was studied by UV/Vis spectroscopy, ESI‐MS experiments and, DFT calculations.