A mononuclear nickel(II) complex based on polypyridyl ligand: synthesis, characterization, and biological activity

Abstract

[Ni(acac)₂(o-NPIP)](CH₃OH)₃ (acac = acetylacetonate), based on the polypyridyl ligand 2-(2-nitrophenyl)imidazo[4,5-f]1,10-phenanthroline) (o-NPIP), has been synthesized and characterized by single-crystal analysis, IR and electronic spectra. In the structure of Ni(II) complex, the coordination sphere around Ni(II) is distorted octahedral with one o-NPIP and two acetylacetonates. DNA binding and human serum albumin (HSA) interactions with the Ni(II) complex have been investigated by electronic absorption and fluorescence measurements, revealing that the Ni(II) complex binds with DNA via intercalative binding. The quenching constants verified a dynamic quenching mechanism between HSA and the Ni complex by fluorescence quenching. ΔG, ΔH, and ΔS at different temperatures (288, 298, and 310 K) indicated that hydrophobic interactions play a major role. Synchronous fluorescence spectral experiments revealed that the Ni(II) complex affected the microenvironment around the tryptophan residue of HSA.

Keywords:

• Polypyridyl Ni(II) complex
• DNA binding
• HSA affinity

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

The work was supported by the NSFC (China) [grant number 21371135]; the Key Program of Tianjin Municipal Natural Science Foundation (China) [grant number 13JCZDJC28200]; the China Postdoctoral Science Foundation [grant number 2014M561195]; the Program of Tianjin Municipal Education Communication [grant number 20130107].