Title
DNA interaction and cleavage studies of ancillary chiral ligand and N,N-donor ligands coordinated platinum(II) complexes
Author
Jegathalaprathaban Rajesh, Mookkandi Palsamy Kesavan, Srinivasan Ayyanaar, Kesavan Karthikeyan, Gurusamy Rajagopal, Periyakaruppan Athappan
Year
2017
Journal
Applied Organometallic Chemistry
Abstract
Four new platinum(II) complexes [Pt(dpen)(bpy)](ClO4)2 (1), [Pt(dpen)(phen)](ClO4)2 (2), [Pt(dpen)(dpq)](ClO4)2 (3) and [Pt(dpen)(dppz)](ClO4)2 (4) comprising of different N,N-donor ligands, viz., 2,2′-bipyridine (bpy), 1,l0-phenanthroline (phen), dipyridoquinoxaline (dpq), dipyrido-[3,2-d:2¢,3¢-f–phenazine] (dppz), and chiral ancillary ligand 1R,2R-1,2-diphenylethylenediamine (dpen) have been synthesized and characterized. The interaction of these complexes 1–4 with calf-thymus DNA (CT-DNA) has been explored using absorption, circular dichroism spectral and cyclic voltammetric studies. The absorption spectrum of complex 4 with dppz ligand exhibits a major red shift with an overall hypochromic as well as a hyperchromic effect in the presence of DNA, other complexes (1–3) show only hypochromism. From these absorption spectral studies, the intercalative ability of the complexes follows the order as, 4 > 3 > 2 > 1, which is further confirmed by CD and cyclic voltammetry measurements. CD spectral studies show that DNA becomes more A-like upon interaction with the complexes 1 & 2 but the complexes 3 & 4 bring about B-form to Z- form DNA conformational transition. The DNA cleavage study of these Pt(II) complexes 1–4 carried out by gel electrophoresis revealed that complexes 1–4 can cleave super coiled (SC) pUC18 DNA efficiently into open circular form (form II) under hydrolytic and oxidative conditions.
Instrument
J-810
Keywords
Circular dichroism, DNA structure, Induced CD, Ligand binding, Biochemistry, Coordination chemistry