Fac-tricarbonyl(pentylcarbonato)(α-diimine)rhenium complexes: One-pot synthesis, characterization, fluorescence studies, and cytotoxic activity against human MDA-MB-231 breast, CCl-227 colon and BxPC-3 pancreatic carcinoma cell lines

A series of pentylcarbonato complexes of the general formula fac-(CO)3(α-diimine)ReOC(O)O(CH2)4CH3 (1–7) was synthesized from the reactions of Re2(CO)10 with the corresponding α-diimines in refluxed 1-pentanol while CO2 was bubbled through the solutions. The α-diimines in 1–7 are 2,2′-bipyridyl, 1,10-phenanthroline, 5-methyl-1,10-phenanthroline, neocuproin, 5,6-dimethyl-1,10-phenanthroline, bathophenanthroline, and bathocuproin, respectively. Complexes 1–7 have been characterized spectroscopically and by elemental analyses. Additionally, 1 and 6 have been characterized in the solid state by X-ray crystallography. The electronic absorption spectra of 1–7 exhibit metal-to-ligand charge-transfer (MLCT) absorption maxima in the range 343–371 nm in acetonitrile. The emission maxima range from 513 to 532 nm. The average life-time and quantum yield are 1.074 ns and 0.011 respectively. Cytotoxicity studies using a few of these pentylcarbonato complexes reveal that the complexes are cytotoxic against BxPC-3 pancreatic, CCL-227 colon, and MDA-MB-231 breast cancer cell lines.