Cu( ii ) complexes of a tridentate N,N,O-donor Schiff base of pyridoxal: synthesis, X-ray structures, DNA-binding properties and catecholase activity

• Published in: New journal of chemistry 2018, Vol.42 (12), p.9588-9597
• Main Authors: Mondal, Satyajit, Chakraborty, Moumita, Mondal, Antu, Pakhira, Bholanath, Blake, Alexander J., Sinn, Ekkehard, Chattopadhyay, Shyamal Kumar
• Format: Article
• Language: English
• Subjects: Binding; Catalysis; Catalytic activity; Crystal structure; Deoxyribonucleic acid; DNA; Imines; Ligands; Oxidation; Reduction
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C8NJ00418H

Two new Cu( ii ) complexes [Cu(L 1 )(N 3 )] ( 1 ) and [Cu(L 1 )(NCS)] n ( 2 ), where HL 1 (( E )-4-((2(dimethylamino)ethylimino)methyl)-5-(hydroxymethyl)-2-methylpyridin-3-ol) is an N,N,O-donor Schiff base ligand, have been synthesized. These complexes were characterized on the basis of their spectroscopic, electrochemical, and other physicochemical properties. X-ray crystal structure determination reveals that in complex 1 , Cu( ii ) is in a square planar geometry with the N,N,O-donor ligand and a terminally coordinated azide ion. In complex 2 , however, Cu( ii ) has a square pyramidal geometry, and apart from the tridentate Schiff base ligand there is a thiocyanate ion, which acts in a μ 1,3 -bridging mode, connecting the adjacent Cu( ii ) atoms in an axial–equatorial fashion forming a one dimensional chain. Cyclic voltammetry shows that the complexes undergo Cu( ii )/Cu( i ) reductions at −0.40 to −0.55 V followed by imine reduction at around −0.7 V. Cu( i )/Cu(0) reduction is observed at approximately −0.9 V. Complex 1 also shows appreciable catalytic activity for the aerial oxidation of 3,5 DTBCH 2 to DTBQ (catecholase activity). Both the complexes also show strong binding affinity towards calf-thymus DNA.