Synthesis, structure, spectroscopic, and DNA binding properties of Co(III) and Ni(II) complexes with ((E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile)

Abstract

Two new complexes, [Co(L)₂]Cl·(MeOH)₂ (1) and [Ni(L)₂]₄·EtOH (2) (L = (E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile), were synthesized and characterized by X-ray crystallography, IR, UV, and fluorescence spectroscopy. According to X-ray crystallographic studies, each metal was six-coordinate with six nitrogens from two ligands. Both complexes form two-dimensional supramolecular networks via hydrogen bonding and π–π interactions. Ultraviolet and visible spectra showed that absorptions arise from π–π ^∗, MLCT, and d–d electron transitions. Fluorescence spectroscopy revealed moderate intercalative binding of these two complexes with EB–DNA, with apparent binding constant (K _app) values of 9.14 × 10⁵ and 3.20 × 10⁵M⁻¹ for Co(III) and Ni(II) complexes, respectively. UV–visible absorption spectra showed that the absorption of DNA at 260 nm was quenched for 2 but quenched then improved for 1 with addition of complexes, tentatively attributed to the effect of the combined intercalative binding and electrostatic interaction for 1.

Keywords:

• (E)-2-(Amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile
• Crystal structure
• Ni(II) complex
• Co(III) complex
• DNA interaction

Acknowledgement

This work was supported by National Natural Science Foundation of China (No. 20971099).

Notes

These authors contributed equally to this work.