title: DNA interaction studies of cobalt (II) mixed-ligand complexes containing dimethyl-1, 10-phenanthroline and dipyrido[3,2-a:2',3'-c]phenazine: the role of methyl substitutions on the mode of binding.
abstract: Two cobalt (II) complexes containing a dipyrido[3,2-a:2',3'-c]phenazine (dppz) base with the general formulation [Co(dppz)(dmp)(2)]Cl(2), where dmp is 4,7-dimethyl-1,10-phenanthroline ligand (4,7-dmp) (1) and 2,9-dimethyl-1,10-phenanthroline ligand (2,9-dmp) (2) were synthesized and characterized. Binding interactions of these complexes with calf thymus DNA were investigated by emission, absorption, circular dichroism, and viscosity studies, and the effects of the positions of methyl substitutions in phenanthroline coligands were investigated. The DNA binding constants obtained from the absorption spectral titrations decrease in the order of 1 > 2, which is consistent with the trend in apparent emission enhancement of the complexes on binding to calf thymus DNA. These observations were supported by circular dichroism spectroscopy and viscosity measurements and reveal that DNA binding affinity of the complexes depends on the position of methyl groups on the phenanthroline ligands.
authors.affiliation: Department of Chemistry, Faculty of Science, Razi University, Kermanshah, Iran. nahidshahabadi@yahoo.com
authors.forename: Nahid
authors.initials: N
authors.lastname: Shahabadi
authors.forename: Soheila
authors.initials: S
authors.lastname: Kashanian
authors.forename: Maryam
authors.initials: M
authors.lastname: Mahdavi
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D003035:Cobalt / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008024:Ligands; D008745:Methylation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry*; D014783:Viscosity
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010618:Phenanthrolines; D010619:Phenazines; C560656:cobalt (II) 4,7-dimethyl-1,10-phenanthroline; C477621:cobalt(II) 2,9-dimethyl-1,10-phenanthroline; C443808:dipyrido(3,2-a-2',3'-c)phenazine; D003035:Cobalt; D004247:DNA; C427203:calf thymus DNA