Half-Sandwich Ruthenium(Ii), Rhodium(Iii) and Iridium(Iii) with Salicylaldimine Ligands Appended by Thiophenyl Arm as Anticancer and Antibacterial Agents

Abstract

Half-sandwich [( p -cym)Ru( L 1 / L 2 )]( 1 and 4 ), [Cp*Rh( L 1 / L 2 )] ( 2 and 5 ), [Cp*Ir( L 1 / L 2 )]( 3 and 6 ) complexes, where L 1 = 2-(( E )-((thiophen-2-yl)methylimino)methyl)-4- tert -butylphenol and L 2 = 2-(( E )-((thiophen-2-yl)methylimino)methyl)-4,6-di- tert -butylphenol, were synthesized and fully characterized by standard spectroscopic techniques (FT-IR, 1 H and 13 C{ 1 H} NMR, HR-ESI-MS) in combination with elemental analysis. Molecular structures of complex 2 , 3 and 4 were further unequivocally determined by single crystal X-ray crystallography. The antiproliferative activity of compounds 1–6 were evaluated using in vitro bioassays in human colorectal cancer (Caco-2) and the triple-negative breast cancer (MDA-MB-231) cell lines. A dose dependency was observed for complexes 1 , 2 and 3 in Caco-2 cells with 1 and 3 exhibiting the highest antiproliferative activity. Complex 1 also displayed pronounced activity against the highly invasive MDA-MB-231 cell line. Complex 4 exhibited selectivity towards MDA-MB-231 while 5 and 6 exhibited pronounced activity against Caco-2 cells. Complexes 1 , 2 and 3 were further evaluated for their antimicrobial activity against two Gram-positive bacteria ( Staphylococcus Aureus and methicillin resistant Staphylococcus Aureus ) and two Gram-negative bacteria ( Escherichia Coli and Klebsiella Pneumonia ). The complexes exhibited good to moderate activity against the Gram-positive bacterial strains, with no activity against the Gram-negative strain.