Synthesis and antiproliferative study of phosphorescent multimetallic Re(I)/Au(I) complexes containing fused imidazo[4,5-f]-1,10-phenanthroline core

Five heterobimetallic Re-I/Au-I and a tri-metallic Re-I/Au-I/Re-I species following the formulas fac-[ReCl (CO)(3)(N boolean AND N boolean AND CAuR)](0/+) and [(fac-[ReCl (CO)(3)(N boolean AND N boolean AND C)])(2)Au](+), where R is an iodide (1), phenylacetylene (2), dodecanethiol (3), 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose (4) and JohnPhos (5) and N boolean AND N boolean AND C is the fused imidazo[4,5-f]-1,10-phenanthroline heterotopic ligand, were synthesised and fully characterised by a variety of spectroscopic and analytical techniques. The resultant complexes are luminescent in the orange region, revealing classical metal-to-ligand charge transfer ((MLCT)-M-3) ((Re (d pi) -> (N boolean AND N boolean AND C)(pi*)) emission in aerated DMSO solution. The red shifted emission observed on going from 3 to 4 suggests that the electronic properties of the gold ancillary ligand are implicated in the emissive properties. Antiproliferative activity in tumour cell lines, lung (A549) and cervix (HeLa) cells revealed that only complex 4 containing a 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose as gold ancillary ligand possesses certain cytotoxicity in both cell lines.

Automated summary

In this study, five heterobimetallic Re-I/Au-I species and one tri-metallic Re-I/Au-I/Re-I species were synthesized and fully characterized. The resultant complexes exhibited luminescence in the orange region, and the emission properties were found to be associated with the electronic properties of the gold ancillary ligand. Antiproliferative activity studies showed that only complex 4, containing a specific gold ancillary ligand, exhibited cytotoxicity in lung and cervical cancer cells.