Photophysical properties and DNA binding studies of novel Eu3+ mixed ligand complex

[Eu(HP)3(NO3)2(o-phen)2·2H2O] complex 1 [Gd(HP)3(NO3)2(o-phen)2·2H2O] complex 2 were synthesized at room temperature and characterized using elemental analysis, UV-visible, FT-IR, NMR and Spectroflourometry. The characteristic emission for synthesized complex 1 was obtained at 618 nm. The Judd-Ofelt intensity parameters Ω2 and Ω4 were calculated. The higher value of Ω2 supports hypersensitive transition indicates asymmetric environment around metal ion. The radiative decay rate Arad, nonradiative rates Anrad, lifetime τ and the luminescent intrinsic quantum yield (η) were calculated. The obtained photophysical parameters support a ligand mediated sensitization of Eu3+ ion. In vitro studies were carried out to examine the interaction of complex 1 with calf thymus DNA(CT-DNA), the binding mechanism and binding constant were evaluated based on spectroscopic studies on complex 1-CT-DNA adduct. Both Spectroflourometry and electronic spectral studies show a gradual decrease in peak intensity (and minor shift) indicative complex CT-DNA intercalation. Simultaneously the peak potential in CV studies also exhibited the similar results. Furthermore, gel electrophoresis study was also performed using pUC18 DNA to support the intercalation with a probable unwinding of pUC18 DNA via intercalating mode.