title: Less symmetrical dicopper(II) complexes as catechol oxidase models--an adjacent thioether group increases catecholase activity.
abstract: 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.
authors.affiliation: Institut für Anorganische und Analytische Chemie der Westfälischen Wilhelms-Universität, Wilhelm-Klemm-Strasse 8, 48149 Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Merkel
authors.forename: Niclas
authors.initials: N
authors.lastname: Möller
authors.forename: Manuel
authors.initials: M
authors.lastname: Piacenza
authors.forename: Stefan
authors.initials: S
authors.lastname: Grimme
authors.forename: Annette
authors.initials: A
authors.lastname: Rompel
authors.forename: Bernt
authors.initials: B
authors.lastname: Krebs
mesh_terms: D004156:Catechol Oxidase / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D007700:Kinetics; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009025:Morpholines / Q000138:chemical synthesis / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry; D010880:Piperidines / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013440:Sulfides / Q000737:chemistry*
chemical_list: C511660:4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-((2-(1-piperidyl)ethyl)aminomethyl)phenol; C511661:4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-((2-(morpholin-4-yl)ethyl)aminomethyl)phenol; C511662:4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-((2-(thiomorpholin-4-yl)ethyl)aminomethyl)phenol; D008024:Ligands; D009025:Morpholines; D009942:Organometallic Compounds; D010636:Phenols; D010880:Piperidines; D013440:Sulfides; D003300:Copper; D004156:Catechol Oxidase