Transition metal complexes of pyrazole head 24-membered polyazamacrocyclic bimetal cores: synthesis, characterization, electrochemistry and spectral study
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A series of new 24-membered macrocyclic CoII, NiII, CuII and ZnII complexes of the ligands L1H2 and L2H2 were prepared by the non-template and template methods respectively. The ligand L1H2 was formed by the condensation of pyrazole-3,5-dicarbohydrazide and glyoxal and all attempts to isolate the ligand L2H2 were unsuccessful. These, ligand and transition metal complexes were characterized on the basis of elemental analysis, IR, 1HNMR, UV–Visible, magnetic susceptibility measurements, ESR, conductivity measurements, FAB-mass and thermal analysis. The redox behavior of metal ions in the polyazamacrocyclic ligand field is also studied. Electroreduction of carbon dioxide to carbon monoxide is mainly focused on using polydentate azamacrocyclic ligands with amine and imine functionalities, based on the electrochemical behavior of nickel (II) ion in the macrocyclic territory.
KeywordsPolyazamacrocyclic Template Pyrazole-3 5-Dicarbohydrazide Glyoxal Electroreduction
The authors thank the USIC and Department of chemistry, Karnatak University, Dharwad for providing spectral facility. Recording of FAB mass spectra (CDRI Lucknow) and ESR spectra (IIT Bombay) are gratefully acknowledged. The authors thank (SB) UGC for providing Research Fellowship in Science for Meritorious Students and Karnatak University (SMP and NVK) for providing research fellowships.
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