Synthesis, structure and catecholase activity study of dinuclear copper(II) complexes†

A series of dinuclear copper(II) complexes as models for the type 3 copper protein catechol oxidase were synthesised. They were characterised by spectroscopic, electrochemical, and in some cases, by single-crystal X-ray diffraction studies: [Cu2(L1)(OH)(EtOH)(H2O)][ClO4]2·H2O 1, [Cu2(L2)(OH)][NO3]22, [Cu2(L3)(OMe)(MeOH)(ClO4)]ClO43, [Cu2(L4)(OH)(MeOH)2][BF4]24, [Cu2(L5)(OMe)][ClO4]2·2MeOH 5, [Cu2(L6)(OMe)(MeOH)(ClO4)]ClO46 and [Cu2(L7)(OMe)(MeOH)(ClO4)]ClO47 (HL1 = 4-bromo-2,6-bis(4-methylpiperazin-1-ylmethyl)phenol, HL2 = 4-bromo-2,6-bis[(2-pyridylmethyl)aminomethyl]phenol, HL3 = 4-bromo-2,6-bis{[2-(2-pyridyl)ethyl]aminomethyl}phenol, HL4 = 4-bromo-2,6-bis{[2-(1-methyl-2-imidazolyl)ethyl]aminomethyl}phenol, HL5 = 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[(2-pyridylmethyl)aminomethyl]phenol, HL6 = 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-{[2-(2-pyridyl)ethyl]aminomethyl}phenol and HL7 = 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-{[2-(1-methyl-2-imidazolyl)ethyl]aminomethyl}phenol). The copper centres are µ-phenoxo bridged by the pentadentate dinucleating ligand and exogenously µ-hydroxo or µ-methanolato bridged. Complex 1 crystallises in P21/c with a = 16.913(3), b = 11.046(2), c = 16.617(3) A, β = 94.06(3)°, U = 3097 A3 and Z = 4. Complex 3 crystallises in P21/n with a = 10.592(2), b = 12.123(2), c = 24.482(5) A, β = 92.97(3)°, U = 3139 A3 and Z = 4. Complex 4 crystallises in Pbcn with a = 16.043(3), b = 12.689(3), c = 15.810(3) A, U = 3218 A3 and Z = 4. Complex 6 crystallises in P21/c with a = 17.889(4), b = 10.401(2), c = 16.269(4) A, β = 92.94(2)°, U = 3023 A3 and Z = 4. Complex 7 crystallises in P21/c with a = 17.349(3), b = 8.828(2), c = 19.797(4) A, β = 94.04(3)°, U = 3025 A3 and Z = 4. A catecholase activity study revealed that only complexes 1, 5, 6 and 7 have significant catalytic activity with respect to the aerial oxidation of 3,5-di-tert-butylcatechol. A kinetic treatment on the basis of the Michaelis–Menten model was applied.

[1]  M. Garland,et al.  Dicopper(II) complexes with hexaaza binucleating ligands derived from isophthaldehyde and di(2-pyridyl) methylamine , 1996 .

[2]  W. Haase,et al.  Structural and Functional Models for the Dinuclear Copper Active Site in Catechol Oxidases: Syntheses, X-ray Crystal Structures, Magnetic and Spectral Properties, and X-ray Absorption Spectroscopic Studies in Solid State and in Solution. , 1996, Inorganic chemistry.

[3]  W. Kaim,et al.  Kupfer – ein “modernes” Bioelement , 1996 .

[4]  A. Rompel,et al.  Spectroscopic and exafs studies on catechol oxidases with dinuclear copper centers of type 3: Evidence for μ-η2:η2-peroxo-intermediates during the reaction with catechol , 1995 .

[5]  B. Feringa,et al.  Modeling dinuclear copper sites of biological relevance - synthesis, molecular-structure, magnetic-properties, and h-1- nmr spectroscopy of a nonsymmetric dinuclear copper(ii) complex - microcalorimetric determination of stepwise complexation of copper(ii) by a nonsymmetric dinucleating ligand , 1995 .

[6]  Thomas G. Spiro,et al.  Common Oxygen Binding Site in Hemocyanins from Arthropods and Mollusks. Evidence from Raman Spectroscopy and Normal Coordinate Analysis , 1994 .

[7]  J. Carpenter,et al.  Recent Structural Work on the Oxygen Transport Protein Hemocyanin , 1994 .

[8]  De-Qi Yuan,et al.  Selective Mono- and Bis-Oxidation of 2,6-bis(Hydroxy-methyl) phenols with Active Manganese Dioxide , 1994 .

[9]  Joseph Haggin,et al.  Chemists Seek Greater Recognition for Catalysis , 1993 .

[10]  O. Carugo,et al.  Hemocyanin and tyrosinase models. Synthesis, azide binding, and electrochemistry of dinuclear copper(II) complexes with poly(benzimidazole) ligands modeling the met forms of the proteins , 1993 .

[11]  M. Andruh,et al.  Oxophily of gadolinium(III) and synthesis of dissymmetric di(Schiff bases) and dissymmetric dinuclear compounds. Crystal structure of [Cu[sub 2]L[prime](OH)](ClO[sub 4])[sub 2][center dot]H[sub 2]O with L[prime] = 2-[N-(2-pyridylethyl)formimidoyl]-6-[N-((dimethylamino)propyl)formimidoyl]phenolato , 1993 .

[12]  C. Creutz,et al.  Syntheses, structures, and properties of copper(II) and copper(I) complexes of the new binucleating ligand 1,3-bis[bis(2-pyridylmethyl)amino]benzene , 1992 .

[13]  L. Thompson,et al.  Structural, magnetic, and electrochemical studies on macrocyclic dicopper(II) complexes with varying chelate ring size , 1989 .

[14]  Mitchell R. Malachowski,et al.  Novel mono- and binuclear Cu(II) complexes: synthesis, characterization and catecholase activity , 1989 .

[15]  G. Fallon,et al.  Exogenous bridging and nonbridging in copper(II) complexes of a binucleating 2,6-bis((N-methylpiperazino)methyl)-4-chlorophenolate ligand. Crystal structures and magnetic properties of bis(.mu.-acetato), dinitrito and bis(azido) complexes. Possible relevance to the type 3 depleted laccase active sit , 1988 .

[16]  O. Kahn,et al.  Synthesis of 2,6-diformyl-4-trifluoromethylphenol , 1988 .

[17]  J. Charland,et al.  Synthesis, structure, and electrochemistry of a novel macrocyclic dicopper(II) complex. Four one-electron-transfer steps producing binuclear copper(III) and copper(I) species and mixed-valence-state species , 1987 .

[18]  P. A. Vigato,et al.  Syntheses, structure and electrochemical characterization of homo- and heterodinuclear copper complexes with compartmental ligands , 1987 .

[19]  C. O'connor,et al.  Binuclear molecules incorporating small molecules as bridging ligands. Magnetic properties and molecular structure of [Cu2L(B)]2+ where B = hydroxide or bromide and HL = 2,6-bis(N-(2-pyridylmethyl)formimidoyl)-4-methylphenol , 1986 .

[20]  A. Jacobson,et al.  Interlayer chemistry between thick transition-metal oxide layers: synthesis and intercalation reactions of K[Ca2Nan-3NbnO3n+1] (3 .ltoreq. n .ltoreq. 7) , 1985 .

[21]  J. Hodgkin.  New Mannich Base Ligands , 1984 .

[22]  J. Bieth,et al.  Isolation and characterization of the polyphenoloxidase from senescent leaves of black poplar , 1984 .

[23]  D. T. Sawyer,et al.  Electrochemical and spectroscopic studies of 3,5-di-tert-butylcatecholato and 3,5-di-tert-butyl-o-semiquinonato complexes of copper(II) , 1983 .

[24]  P. A. Vigato,et al.  The preparation of binuclear complexes and their catalytic behaviour in the oxidation of 3,5-di-butycatechol , 1983 .

[25]  S. Lippard,et al.  A monohydroxobridged, strongly antiferromagnetically coupled dicopper(II) center in a binucleating macrocycle. Comparisons with binuclear copper sites in biology , 1981 .

[26]  Kazuhiko Ida,et al.  Reaction between Various Copper(II) Complexes and Ascorbic Acid or 3,5-Di-t-butylcatechol , 1980 .

[27]  J. Dodge,et al.  UNUSUAL STRUCTURAL AND REACTIVITY TYPES FOR COPPER(I). SYNTHESIS AND STRUCTURAL AND REDOX PROPERTIES OF BINUCLEAR COPPER(I) COMPLEXES WHICH ARE PROBABLY THREE COORDINATE IN SOLUTION AND EXPERIENCE INTERMOLECULAR METAL‐METAL INTERACTIONS IN THE SOLID STATE , 1980 .

[28]  F. Urbach,et al.  Binuclear metal complexes. 1. Dicopper(II) complexes with binucleating ligands derived from 2-hydroxy-5-methylisophthalaldehyde and 2-(2-aminoethyl)pyridine or histamine , 1978 .

[29]  H. S. Mason,et al.  OXYGEN TRANSFER AND ELECTRON TRANSPORT BY THE PHENOLASE COMPLEX1 , 1955 .