Magnetic, catalytic, EPR and electrochemical studies on binuclear copper(II) complexes derived from 3,4-disubstituted phenol

Abstract

New symmetrical compartmental binucleating ligands 2,6-bis[N-(2-{dimethylamino}ethyl)-N-methyl)aminomethyl]-3,4-dimethylphenol [HL 1 ] and 2,6bis[N-(2-{diethylamino}ethyl)-N-ethyl)aminomethyl]-3,4-dimethylphenol [HL 2 ], and their copper(II) complexes [Cu 2 L 1-2 (X)]ClO 4 , (X = NO 2-, OAcand OH-) have been prepared. Spectral, catalytic, magnetic, EPR and electrochemical studies have been carried out. A catecholase activity study indicates that only HL 1 complexes have efficient catalytic activity due to a less sterically hindered methyl group and enhanced planarity (larger-2J values) with respect to the oxidation of 3,5-di-t-butylcatechol to the corresponding quinone. Variable temperature magnetic susceptibility studies of the complexes show antiferromagnetic interaction between the copper atoms. X-band EPR signals could not be observed for polycrystalline samples both at room temperatures and liquid nitrogen, consistent with two antiferrromagnetically coupled copper centres in the solid state. EPR spectral studies in methanol solvent show welldefined four hyperfine signals at room temperature due to decomposition of the dimer into monomers. This however is not seen in frozen methanol glass, may be owing to restructuring of the monomers into dimers due to an increase in viscosity of the solvent. Electrochemical studies revealed chemically irreversible behaviour due to chemical or/and stereochemical changes subsequent to electron transfer.

Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone

“…The low value of the magnetic moment is attributed to the antiferromagnetic coupling interaction between two metal ions. This fact suggests the dinuclear nature of the Cu(II) complexes [33].…”

Binuclear Mixed Valence Oxovanadium(IV/V) Complexes Containing a [OVIV(μ‐Ooxo)(μ‐Ophen)VVO]2+ Core: Synthesis, EPR Spectra, Molecular and Electronic Structure

“…Materials: Bis(acetylacetonato)oxovanadium() [26] and the ligands [27] were prepared as reported in the literature. All the starting chemicals were analytically pure and used without further purification, and the solvents were purified by standard procedures.…”

Studies on Synthesis and Spectral Characterization of Some Transition Metal Complexes of Azo-Azomethine Derivative of Diaminomaleonitrile

“…DMSO at the 100 mVs −1 scan rate shows a well-de�ned redox process corresponding to the formation of the Cu(II)/Cu(I) couple at pa = 0.562 V and the associated cathodic peak at pc = 0.145 V. is couple is found to be irreversible with Δ p ( pa − pc ) = 417 V. e result was veri�ed by varying the scan rates with peak potentials. Table S1 infers that the pc and pa values with different scan rates and the difference in the value of pa − pc are larger than the value required for a reversible process (59 mV) which indicates that the electron transfer process is irreversible [34]. e oxovanadium [35] complex exhibited two-step oxidation peaks at 0.223 V and 0.661 V and one reduction peak at −0.702 V. e redox process involves V(IV) → V(III) → V(II) → V(IV).…”