Abstract

GREEN SYNTHESIS, SPECTRAL, THE RMAL AND BIOLOGICAL INVESTIGATIONS OF Cr (III), Ni(II) AND Cu(II) COMPLEXESOF 4- AMINOPYRIDINE AND NITRITOLIGANDS

K. Dhaveethu, S.Padmavathy, T. Ramachandramoorthy, K. Thirunavukkarasu*

ABSTRACT

Microwave assisted synthesis is called green synthesis because of the following reasons: 1) pollution free synthesis 2) reduction of reaction time from many hours to few minutes 3) its instantaneous ‘in-core’ heating of materials in a homogeneous and selective manner 4) its ability to increase the probability of molecular impacts 5) decrease in the activation energy and 6) no need of solvents. Microwave-assisted synthesis of Cr(III), Ni(II) and Cu(II) complexes with 4–aminopyridine and nitrite ligands is reported with spectral characterizations and thermal studies. IR results reveal the O-coordinated nature of coordination of nitrite ligand (O-nitrito) and the 4–aminopyridine ligand coordinates to the metal ions through its ring nitrogen atom. Electronic spectra suggest distorted octahedral geometry for Cr(III), Ni(II) complexes and tetragonally distorted octahedral Cu(II) complex. EPR studies identify the distortion in the geometry of the complexes. XPS studies confirm the O-coordination of nitrite ligand and the oxidation state of the metal ions. The complexes were screened for antibacterial and antifungal activities on pathogenic bacteria and fungi. The complexes show better activity against these bacteria and fungi than the free ligands. A correlation is observed with the microbial activities of the complexes and their structure.

Keywords: Microwave irradiation; nitrito complex; 4–aminopyridine; biological activities.