New photo-CORMs: Deeply-coloured biocompatible rhenium complexes for the controlled release of carbon monoxide

Air- and water-stable rhenium carbonyl complexes are investigated as CO-carriers for studying the light-dependent release of small amounts of carbon monoxide under physiological conditions. The reported very low quantum yields are in a suitable range for studying potential applications as photochemical CO-releasing molecules (Photo-CORMs) without rapidly reaching cytotoxic levels of carbon monoxide. Preliminary results on bio-compatibility and selective uptake of the compounds into human colon carcinoma cells (Caco-2 cell line) are described.