Complexes based N,N-donors (2,2′-bipyridyl & 2-(2-aminophenyl)benzimidazole); Synthesis, characterization, DNA interaction and toxicity assessment against Chlorella vulgaris microchlorophyte; X-ray crystal structure of [Zn(bpy)3)]Cl2

Abstract

The syntheses of some N,N-donors, 2,2′-bipyridyl (bpy) and 2-(2-aminophenyl)benzimidazole (HAPB) complexes are reported. The structures of the complexes are discussed on the bases of their IR, NMR (1H, 13C, 31P), UV–Vis, and EI and maldi-mass spectra, elemental analyses, molar conductivities and TGA behaviour. HAPB coordinates to the central metal ions in neutral monodentate {[Au(HAPB)Cl3], cis-[MoO2(HAPB)(DMF)Cl2], [Pd(HAPB)(H2O)Cl2], [M(HAPB)(PPh3)Cl2] and [Pd(bpy)(HAPB)Cl]Cl} or bidentate {[Zn(HAPB)2](ClO4)2, [Zn(PPh3)(HAPB)Cl2(H2O)], [Ag(L)(HAPB)]NO3 (L = bpy, PPh3), [M(HAPB)Cl2] (M(II) = Pd, Pt), [Rh(HAPB)2Cl2]Cl and [Rh(PPh3)(HAPB)Cl]Cl2} fashion, via the imidazole N- atom or both amino N- and imidazole N-atoms, respectively. The X-ray crystal structure of the complex, [Zn(bpy)3)]Cl2, has been determined. It has been crystallized in a monoclinic lattice with space group symmetry P2/n. The Zn(II) ion is coordinated in a distorted octahedral geometry by the two nitrogen atoms of three bpy moieties in the expected neutral bidentate fashion. The stoichiometries and the formation constants of Pd(II), Pt(II), [M(L)Cl2] (L = bpy, 2PPh3) complexes have been determined using both Job's and the molar ratio methods. The DNA-binding constants of some of the complexes have been calculated based on UV–vis spectroscopy. The results indicate intercalative CT-DNA binding in view of their hypochromism and low-to-moderate binding abilities. The DNA binding abilities of the complexes follow the order [Pd(PPh3)(HAPB)Cl2] > [Pt(HAPB)Cl2] > [Pd(HAPB)(H2O)Cl2] > [Pd(HAPB)Cl2], which may result from steric hindrance around the metal ions comes from HAPB with bpy or PPh3 chelates. Moreover, the toxicity of HAPB and its Pd(II) complexes against the microchlorophyte (Chlorella vulgaris) have been assessed.