Light-responsive paper strips as CO-releasing material with a colourimetric response

Carbon monoxide (CO) is known for its multifaceted role in human physiology, and molecules that release CO in a controlled way have been proposed as therapeutic drugs. In this work, a light-responsive CO-releasing molecule ( ) showed a strong colourimetric response upon photochemical CO-release, owing to the tight conjugation of a Mn(i) tricarbonyl centre to a dabsyl chromophoric ligand ( ). Whereas the complex was very stable in the dark in nitrogen-purged aqueous media, CO-release was effectively triggered using 405 nm irradiation. , and the inactive product have been investigated by DFT and TD-DFT calculations. Only mild toxicity of was observed against LX-2 and HepaRG® human cell lines (IC ∼ 30 μM). Finally, to develop a CO storage and release material that is readily applicable to therapeutic situations, was loaded on low-cost and easily disposable paper strips, from which the light triggered CO-release was conveniently visible with the naked eye.