Synthesis, Characterization, Photo-Physical Properties and Biological Activity of [Ru(p-cymene)(tmp)Cl]∙CH2Cl2, [Ir(ppy)2(tmp)]∙CH2Cl2 and Ru(p-cymene)(PPh3)Cl2 Complexes

Abstract

In this study, two novel ruthenium(II) and iridium(III) complexes with tris(2-methoxyphenyl)phosphine (tmp) and ruthenium(II) with triphenylphosphine (PPh3) ligands; [Ru(p-cymene)(tmp)Cl]·CH2Cl2 (1), [Ir(ppy)2(tmp)]·CH2Cl2 (2) were synthesized together with a known complex of Ru(p-cymene)(PPh3)Cl2 (3). The complexes were analyzed using single-crystal X-ray diffraction, elemental analysis, and spectroscopy techniques. The structures of complexes 1 and 3 are both distorted tetrahedral geometry. Each of them has two independent molecules with asymmetric units in one unit cell. They have the same backbone of Ru(p-cymene)ClL2; L is a different kind of ancillary ligand. Complex 1 has L as a bidentate of P and O donors. Complex 3 has L as PPh3 and Cl ligands. Complex 2 shows a distorted octahedral geometry of a bis complex with two 2-phenyl pyridine molecules and a chelating ring of P and O from the tmp ligand. All kinds of molecules were studied for the intramolecular forces in their crystal structures. Hydrogen bonds were mainly found. All complexes' photophysical properties (UV-Visible absorption and luminescence) were investigated. The maximum absorption wavelength of complex 3 is presented at 395 and 496 nm. Regarding the DFT/TDDFT calculation of complex 3, its electronic transition is a mixed charge transfer transition (CT) type. Among studied 1-3 complexes, only complex 2 was observed in the emission band at 522 nm (excitation at 380 nm). Complex 2 showed selective sensing properties toward Fe(III) ion in dimethylformamide (DMF) solution with a 1:1 stoichiometric binding mode. The binding constant calculated from the Benesi-Hildebrand plot was 8.1×102 M-1. All complexes were tested for their biological activities on antibacterial, antifungal, anti-yeast, and anti-breast cancer. Complexes 1 and 2 displayed the antibacterial on Gram- positive bacteria, but not for complex 3. The MIC/MBC values for complex 1 have been observed at 64/128 μ/mL for both Staphylococcus aureus ATCC25923 (SA) and methicillin-resistant Staphylococcus aureus (MRSA), which indicates moderate activity. Complex 2 showed MIC/MBC values for SA and MRSA inhibition of 16/32 μ/mL and 32/32 μ/mL, respectively. Only complex 3 exhibited cytotoxicity against MCF-7 by MTT assay with IC50 15.99 μM which was more potent than that of cisplatin (42.2 μM), a commercial drug, for 2.6 folds.