Copper complexes of non-steroidal anti-inflammatory drugs: an opportunity yet to be realized

Coordination chemistry with pyrazole-based chelating ligands: molecular structural aspects

New dinucleating ligands having two metal-binding sites bridged by an imidazolate moiety, Hbdpi and HMe4bdpi (Hbdpi = 4,5-bis(di(2-pyridylmethyl)aminomethyl)imidazole, HMe4bdpi = 4,5-bis(di(6-methyl-2-pyridylmethyl)aminomethyl)imidazole), have been designed and synthesized as model ligands for copper−zinc superoxide dismutase (Cu,Zn-SOD). The corresponding mononucleating ligand, MeIm(Py)2 (MeIm(Py)2 = ((1-methyl-4-imidazolyl)methyl)bis(2-pyridylmethyl)amine), has also been synthesized for comparison. The imidazolate-bridged Cu(II)−Cu(II) homodinuclear complexes represented as [Cu2(bdpi)(CH3CN)2](ClO4)3·CH3CN·3H2O (1), [Cu2(Me4bdpi)(H2O)2](ClO4)3·4H2O (2), a Cu(II)−Zn(II) heterodinuclear complex of the type of [CuZn(bdpi)(CH3CN)2](ClO4)3·2CH3CN (3), and a Cu(II) mononuclear complex of [Cu(MeIm(Py)2(CH3CN)](ClO4)2·CH3CN (4) have been synthesized, and the structures of complexes 1−4 were determined by X-ray crystallography. The Cu(II)−Zn(II) distance of 6.197(2) A in 3 agrees well with that of native Cu,Zn-S...

Synthesis and Characterization of Imidazolate-Bridged Dinuclear Complexes as Active Site Models of Cu,Zn-SOD

The synthesis of five new Cu(II) compounds of formula [Cu(HBIP)(C(2)O(4))].H(2)O (1), [Cu(HBIP)(C(2)O(4))(OH(2))].2H(2)O (2), [{Cu(HBIP)Cl}(2)(m-C(2)O(4))].2H(2)O (3), [{Cu(BIP)}(2)(m-C(2)O(4))].2H(2)O (4) and [{Cu(BIP)}(2)(m-C(2)O(4))].6H(2)O (5), together with their spectral and magnetic characterization, is reported. Crystal structures of compounds 2, 3 and 5 have been solved. All these compounds crystallize in the triclinic system, space group Po, with a = 7.3322(3) A, b = 10.014(1) A, c = 11.541(1) A, alpha = 113.22(1) degrees, beta = 91.37(1) degrees, gamma = 94.51(1) degrees, Z = 2 for compound 2; a = 7.444(2) A, b = 8.518(2) A, c = 11.231(2) A, alpha = 97.45(2) degrees, beta = 98.99(2) degrees, gamma = 97.95(2) degrees, Z = 1 for compound 3; and a = 7.977(1) A, b = 8.656(1) A, c = 11.807(1) A, alpha = 69.06(1) degrees, beta = 86.07(1) degrees, gamma = 67.36(1) degrees, Z = 1 for compound 5. In compound 2 the asymmetric unit consists of one isolated neutral [Cu(HBIP)(C(2)O(4))(OH(2))] molecule and two noncoordinated water molecules. The Cu(II) ion is five-coordinated (4+1 coordination mode) with HBIP and oxalato entities acting as bidentate ligands and the water molecule as the fifth ligand. The structure of compound 3 is made up of centrosymmetric binuclear [{Cu(HBIP)(Cl)}(2)(m-C(2)O(4))] units and noncoordinated water molecules. The two copper atoms are linked through a bis-bidentate oxalato group leading to a metal-metal separation of 5.28(3) A. The coordination stereochemistry of the CuN(2)O(2)Cl chromophore is approximately SP. Compound 5 exhibits a structure built of ladder-like chains. In these chains the rungs are constituted by the neutral dinuclear centrosymmetric [(BIP)Cu(C(2)O(4))Cu(BIP)] entities. The oxalato group bridges two copper atoms in a bis-bidentate fashion, whereas the BIP acts as a tridentate ligand, connecting through their carboxylate groups these dimeric units along the a axis. The copper atom is involved in a five-coordinated CuN(2)O(2)O' chromophore, with a coordination geometry intermediate between SP and TBP. The magnetic properties of all complexes have been investigated. Compound 1 and 2 follow a Curie-Weiss law with very low values of theta. The other three compounds exhibit an antiferromagnetic coupling, with 2J = -265 cm(-)(1) for 3, 2J = -108 cm(-)(1) for 4, and 2J = -5.7 cm(-)(1) for 5. The strength of the exchange interaction is discussed on the basis of the structural features and correlated with published magneto-structural data on similar oxalato-bridged copper(II) compounds.

Synthesis, Crystal Structure, and Magnetic Properties of Oxalato-Copper(II) Complexes with 3,3-Bis(2-imidazolyl)propionic Acid, an Imidazole-Carboxylate Polyfunctional Ligand: From Mononuclear Entities to Ladder-Like Chains.

SOD activities of the copper complexes with tripodal polypyridylamine ligands having a hydrogen bonding site

A new dinucleating ligand, 1,5-bis(1-pyrazolyl)-3-[bis(2-imidazolyl)methyl] azapentane (Hbpzbiap), containing pyrazoles and imidazoles has been designed and synthesized. The synthesis and characterization of the copper complexes with the ligand Hbpzbiap and its dehydronated form are described. This study is aimed at modeling the active site of copper−zinc superoxide dismutase (SOD). Single crystals of the imidazolato-bridged complex [Cu2(bpzbiap)Cl3] (1) and non-imidazolato-bridged complex [Cu2(Hbpzbiap)Cl4] (2) were obtained and their structures determined by X-ray diffraction. Both structures show two copper centers in two different coordination environments:  a distorted square pyramid and a distorted tetrahedron. The Cu−nitrogen bond lengths range from 1.919(4) to 2.039(3) A and are as expected. The copper−copper distances from 5.566(1) to 6.104(1) A being only slightly shorter than that found in bovine erythrocyte SOD. Temperature-dependent magnetic susceptibility study of 1 shows antiferromagnetic b...

High Superoxide Dismutase Activity of a Novel, Intramolecularly Imidazolato-Bridged Asymmetric Dicopper(II) Species. Design, Synthesis, Structure, and Magnetism of Copper(II) Complexes with a Mixed Pyrazole-Imidazole Donor Set.

Willem L. Driessen

Papers

High Superoxide Dismutase Activity of a Novel, Intramolecularly Imidazolato-Bridged Asymmetric Dicopper(II) Species. Design, Synthesis, Structure, and Magnetism of Copper(II) Complexes with a Mixed Pyrazole-Imidazole Donor Set.