Synthesis, X-ray structure, spectroscopic electrochemistry, anti-nociceptive activity and DFT study of cis-[Ru(EPh3)(L)Cl2] complexes (E = P, as and Sb) (L = thioether-azoimine tridentate SNN donor ligands). (1st July 2021)

• Record Type: Journal Article
• Authors: Al-Noaimi, Mousa; Qnais, Esam; Awwadi, Firas F.; Alwahsh, Manal I.
• Is Part Of: Polyhedron. Volume 202(2021)
• Publication Date: 2021-07-01
• Subjects: Ruthenium -- Antinociceptive activity -- X-ray structures -- DFT calculations -- Electrochemistry; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2021.115195
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: New complexes cis-[Ru(EPh3 )(L1)Cl2 ] (1–3) {L1 = (2-PhS)C6 H4 NNC(COCH3 )-NC6 H5, E = P (1); As (2), Sb (3)} and cis-[Ru(PPh3 )(L4)Cl2 ] (4) {L4 = (2-CH3 S)C6 H4 NN-(COCH3 )NC6 H5 } have been synthesized by reacting Ru(EPh3 )3 Cl2 and thioether-azoimine ligand (H2L1 and H2L4). The structures of 2 and 4 have been confirmed by single crystal X-ray diffraction. Cyclic voltammetric studies show one quasi reversible Ru(III)/Ru(II) oxidation couple and one L(0/−1) electron reduction, respectively. The antinociceptive activity for the ligands (H2L1 and H2L4) and the complexes (1–4) were tested using acetic-acid-induced writhing test. The compounds 2 and 4 possessed strong antinociceptive activity and thus are strong candidates for further detailed studies. The structure–activity relationships were also investigated by comparing the antinociceptive activity of complexes 1 and 4. The results show that changing the phenyl group as in complex 1 to a methyl group as in complex 4 increased the antinociceptive effects. The electronic structure, redox and absorption properties of the complexes have been explained based on DFT and TDDFT calculations. Abstract: The complexes cis -[Ru(EPh3 )(L1)Cl2 ] (1 –3 ) {L1 = (2-PhS)C6 H4 N = NC(COCH3 )-NC6 H5, E = P (1 ); As (2 ), Sb (3) } and cis -[Ru(PPh3 )(L2)Cl2 ] (4 ) {L4 = (2-CH3 S)C6 H4 N = N-(COCH3 ) = NC6 H5 } have been synthesized by reacting Ru(EPh3 )3 Cl2 and thioether-azoimine ligand (H2 L1 and H2 L4) in refluxing ethanol. The complexes have been characterized by IR, NMR, UV–Vis spectroscopy and cyclic voltammetry. The structures of 2 and 4 have been confirmed by single crystal X-ray diffraction. The electronic spectra of the complexes show MLCT and intense LLCT transitions. Cyclic voltammetric studies show one quasi reversible Ru(III)/Ru(II) oxidation couple and one L(0/−1) electron reduction, respectively. Antinociceptive activity study shows that the most active compound is complex 4 which has 70% inhibition at 45 µmol/Kg. The ligands were inactive, however, the complexes 1 –4, significantly reduced the pain response in dose dependent manner ( p < 0.05) in the acetic-acid-induced writhing test relative to control ligands. The compounds 2 and 4 possessed strong antinociceptive activity and thus are strong candidates for further detailed studies. The structure–activity relationships were also investigated by comparing the antinociceptive activity of complexes 1 and 4 . The results show that changing the phenyl group as in complex 1 to a methyl group as in complex 4 increased the antinociceptive effects. The electronic structure, redox and absorption properties of the complexes have been explained based on DFT and TDDFT calculations.