Synthesis, Structural Characterization, Antimicrobial and DNA binding studies of homoleptic zinc and copper complexes of NO Schiff bases derived from homoveratrylamine

Abstract Four new homoleptic zinc ( 1 and 2 ) and copper ( 3 and 4 ) complexes of two Schiff base ligands ( L 1 H and L 2 H ) derived from 2-(3,4-dimethoxyphenyl)ethan-1-amine ( 5 ), a dimethyl derivative of dopamine were synthesized. All four complexes were well characterized by elemental analysis, FT-IR and UV–Vis., spectroscopy. Further, the zinc complexes ( 1 and 2 ) were characterized by 1 H and 13 C{ 1 H} NMR spectroscopy while the copper complexes ( 3 and 4 ) by single crystal X-ray diffraction. The characterization data of complexes revealed strong coordination via azomethine nitrogen (N) and phenolate oxygen (O) of deprotonated ligands ( L 1 and L 2 ) as NO donors of composition [Zn/Cu( L 1-2 ) 2 ] ( 1 – 4 ). The CT-DNA binding affinity of complexes 1 , 2 and 4 was assessed using electronic absorption titration method which showed avid binding through intercalation mode and the binding constant ( K b ) was found in the order of 10 5 –10 6  M −1 . The compounds ( 1 – 5 ) were screened for dose dependent antimicrobial activity by agar well diffusion method against pathogenic antibacterial strains, E. coli, S. aureus and antifungal strain, C. albicans . The compounds showed significant toxicity to these pathogens.