Rhenium(II) nitrosyl complexes: synthesis, characterization, DFT calculations and DNA nuclease activity

Abstract

The rhenium(II) dinitrosyl and mononitrosyl complexes, i.e. [Re(NO)₂(CN)₄]·(Phen)₂·2H₂O (1) and PhenH[Re(NO)(CN)₄(H₂O)]·(Phen)·3H₂O (2) have been isolated and characterized. The X-ray crystal structure of 2 reveals that Re(II) is octahedrally coordinated with one nitrosyl, four cyanides, and one water, with one phenanthroline protonated to compensate the charge of the Re(II) center. The crystal structure shows chemically significant non-covalent interactions like hydrogen bonding involving the uncoordinated water and π–π interactions between phenanthrolinium and phen. The structures of both complexes have been optimized by DFT. Absorption and emission spectral studies and viscosity measurements indicate that both 1 and 2 interact with calf thymus DNA through partial intercalation of DNA bases. The intrinsic-binding constants, obtained from UV–vis spectroscopic studies, are 1.2 × 10⁴ and 7.2 × 10⁴ M⁻¹ for 1 and 2, respectively. Both 1 and 2 are capable of inducing cleavage of plasmid DNA in the presence of H₂O₂ to form the supercoiled form to nicked circular form. The spectroscopic results of DNA binding are supported by molecular docking studies.

Graphical Abstract

The synthesis of mono and dinitrosyl rhenium(II) complexes were done. Mono nitrosyl complex was characterized by single crystal X-ray diffraction, which was further supported by DFT and Hirshfeld surface analysis. DNA binding and nuclease activity of both complexes were performed.

Keywords:

• Rhenium(II) nitrosyl complexes
• DFT study
• Hirshfeld surface analysis
• DNA binding study
• Molecular docking

Acknowledgements

S.G. thanks UGC for financial support in the form of a Minor Research Project [SPSW-044/09-10(ERO)]. The single crystal X-ray diffractometer used in this work has been funded by the Department of Science and Technology (DST-FIST), New Delhi, India, to the Department of Chemistry, J.U. The authors are thankful to UGC, New Delhi, for funding UVP Bio Doc-IT GEL Imaging system in the form of a Major Research Project to KKM [39-706/2010(SR)].