Synthesis, crystal structures, luminescent properties, theoretical calculation, and DNA interaction of the cadmium(II) and lead(II) complexes with o-aminobenzoic acid and 1,10-phenanthroline

Two complexes, namely [Cd(Phen)(o-AB)2] (I) and [Pb(Phen)(o-AB)] (II) (Phen = 1,10-phenanthroline, o-AB = o-aminobenzoic acid), have been synthesized and characterized by elemental analysis and X-ray diffraction single-crystal analysis (CIF files CCDC nos. 910307 (I), 898292 (II)). Complex I is six coordinated by two nitrogen and four oxygen atoms from the Phen and o-AB to furnish a distorted octahedral geometry. Complex II is six coordinated by two nitrogen and four oxygen atoms from the Phen and o-AB to furnish an umbrella-like geometry. The complexes exhibit intense fluorescence at room temperature. The interaction between complex I and calf thymus DNA was also investigated by UV absorption spectra, fluorescence emission spectra and viscometry. The nature of the binding seems to be mainly an electrostatic interaction between DNA and complex I. Theoretical studies of the title complexes were carried out by density functional theory (DFT) B3LYP method.