Template synthesis and spectral characterization of some Schiff base complexes derived from quinoxaline-2-carboxaldehyde and L-histidine

Abstract

New Schiff base complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized by template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and the metal compound, and were characterized by elemental analysis, fourier transform infrared spectroscopy, electronic spectra, conductance measurements, magnetic susceptibility measurements, ESR spectra, and thermal analysis. In all the complexes, the Schiff base coordinates through azomethine nitrogen, quinoxaline nitrogen, and carboxylato oxygen. The physicochemical and spectroscopic measurements reveal square planar geometry for the copper(II) complex, tetrahedral geometry for the manganese(II), cobalt(II), and zinc(II) complexes, and octahedral geometry for the iron(III) and nickel(II) complexes.

Keywords:

• Schiff base complex
• Template method
• Quinoxaline-2-carboxaldehyde
• L-histidine
• Amino acid

Acknowledgments

Manju Sebastian thanks Kerala State Council for Science, Technology and Environment, Kerala and Digna Varghese thanks Council of Scientific and Industrial Research, India for granting research fellowships. The authors thank Department of Science and Technology, India, for allowing them to use the Sophisticated Analytical Instrumentation Facility (SAIF) at IIT Bombay for the EPR spectral data and at the Sophisticated Test & Instrumentation Centre, Cochin University of Science and Technology for the elemental analyses and NMR spectral analysis.