Synthesis and spectroscopy of Co(II), Ni(II), Cu(II) and Zn(II) complexes derived from 3,5-disubstituted-1H-pyrazole derivative: a special emphasis on DNA binding and cleavage studies.

A series of novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of 1H-pyrazole-3,5-dicarboxylic(2'-hydroxy-3'-hydrazinequinoxaline) has been prepared and characterized by the spectral and analytical techniques. Cu(II) ion reacts with the ligand LH(3) and forms the complex in one compartment of the ligand whereas, the other compartment remains free. In Co(II), Ni(II) and Zn(II) complexes both compartments of LH(3) are involved in the coordination. DNA binding/cleavage studies were revealed the stronger binding capability of the present Ni(II) complex, confirmed by the absorbance, viscometric and gel-electrophoresis studies. Similarly, remaining complexes do the same in the ligand field with lesser binding constants, subsequently, no complex was found to cleave the DNA. Finally, Cu(II) complex shows growth inhibitory activity against biogram.