Synthesis, crystal structure, spectral and magnetic studies and catecholase activity of copper(II) complexes with di- and tri-podal ligands

The catecholase activity of two dinuclear Cu(II) complexes with distant metal centers is discussed together with solid state and solution studies. The crystal structure for one of them, [Cu2(diep)(H2O)4](ClO4)4·2H2O, is described, showing the two copper ions are 7.457 A apart and in a square pyramidal coordination. Both complexes display a weak antiferromagnetic coupling in the solid state that is manifest in the dimer EPR spectra obtained in frozen solution. The pH-potentiometric speciation performed in 1 : 1 MeOH–H2O allowed the assignment of hydrolyzed copper species as those catalytically active in the oxidation of 3,5-di-tert-butylcatechol (DTBC). The kinetic measurements led us to propose behavior consistent with Michaelis–Menten plus a linear dependence of the initial rate on [DTBC]. This can be associated with the presence of more than one catalytically active species, which is consistent with the evidence of several differently hydrolyzed species shown in the predominance diagrams. Product characterization studies led to establishing the formation of hydrogen peroxide during the catalytic cycle, while semiquinone and superoxide radicals were detected by EPR spectroscopy, supporting one-electron transference at each of the copper centers.

Mechanistic insight on the catecholase activity of dinuclear copper complexes with distant metal centers

Synthesis of new tripodal ligand 5-(bis(3,5-dimethyl-1H-pyrazol-1-ylmethyl)amino)pentan-1-ol, catecholase activities studies of three functional tripodal pyrazolyl N-donor ligands, with different copper (II) salts

Recent advances in coordination chemistry of metal complexes based on nitrogen heteroaromatic alcohols. Synthesis, structures and potential applications

The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety (L1–L6) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6–31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds (L1–L6), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity.

New thiazole, pyridine and pyrazole derivatives as antioxidant candidates: synthesis, DFT calculations and molecular docking study

New synthesis of two tridentate bipyrazolic compounds and their cytotoxic activity tumor cell lines

The tridentate ligand N,N-Bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane (L) has been prepared in one step by condensation of two equivalents of 1-hydroxymethyl-3,5-dimethylpyrazole with one equivalent of 2-aminoethanol. This reaction is carried out under microwave irradiation (60 W) in the absence of solvent for 20 min [1]. Using this ligand L a new Cu(II) dinitrate complex has been prepared. The singlecrystal X-ray structure of the title compound, [N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane] (3,5-dimethylpyrazole)copper(II) dinitrate, revels that the copper (II) ion is coordinated to two pyrazole nitrogens, one tertiary amine nitrogen of the ligand L and 3,5-dimethylpyrazole, and in the apical position by an alcohol O atom.

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Synthesis and X-Ray Structure of [N,N-Bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane](3,5-dimethylpyrazole) copper(II) dinitrate

Synthesis, characterization, reaction mechanism prediction and biological study of mono, bis and tetrakis pyrazole derivatives against Fusarium oxysporum f. sp. Albedinis with conceptual DFT and ligand-protein docking studies.

Mohamed El Kodadi

Papers

Synthesis of new tripodal ligand 5-(bis(3,5-dimethyl-1H-pyrazol-1-ylmethyl)amino)pentan-1-ol, catecholase activities studies of three functional tripodal pyrazolyl N-donor ligands, with different copper (II) salts

New thiazole, pyridine and pyrazole derivatives as antioxidant candidates: synthesis, DFT calculations and molecular docking study

New synthesis of two tridentate bipyrazolic compounds and their cytotoxic activity tumor cell lines

Synthesis and X-Ray Structure of [N,N-Bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane](3,5-dimethylpyrazole) copper(II) dinitrate

Synthesis, characterization, reaction mechanism prediction and biological study of mono, bis and tetrakis pyrazole derivatives against Fusarium oxysporum f. sp. Albedinis with conceptual DFT and ligand-protein docking studies.