Double mu(2)-(phenoxido)-bridged dinuclear and polynuclear nickel(II) complexes: magnetic properties and DNA/protein interaction

Abstract

One dinuclear and one 1D polymeric nickel(II) complex, namely {[Ni2(HL)2(pa)2(H2O)2]·DMF} (1) and {[Ni2(HL)2(ppda)(H2O)2]·DMF·H2O}n (2) (H2L = (E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol, pa = 3-phenylacrylate, ppda = p-phenylenediacrylate) have been synthesized and characterized by X-ray single crystal structure determination. Complex 1 is double phenoxo-bridged dinuclear Ni(II) complex, whereas complex 2 is a 1D polynuclear chain where double phenoxo-bridged dinuclear units are connected through bridging ppda ligands. The variable temperature magnetic behavior of the complexes was studied using the Hamiltonian H = −JS1S2, S1 = S2 = SNi and confirms the presence of an overall antiferromagnetic interaction in both complexes. Good agreement between the experimental and simulated curves were found using the parameters: gNi = 2.15, DNi = 4.0 cm−1 and JNi-Ni = −0.60 cm−1 for 1, and gNi = 2.15, DNi = 4.8 cm−1 and JNi-Ni = −3 cm−1 for 2. The interactions of the complexes with CT-DNA were investigated using UV-Vis absorption and fluorescence spectroscopic methods and they show that both the complexes interact with CT-DNA. The intrinsic binding constants values for interaction with CT-DNA are 3.9(±0.10) × 105 and 3.43(±0.09) × 105 M−1 for 1 and 2, respectively. The interactions of the complexes with bovine serum albumins (BSA) and human serum albumins (HSA) were also studied using electronic absorption and fluorescence spectroscopic techniques and the results show that both complexes interact with the serum albumins via a ground state association process.