The chemistry, biology and design of photochemical CO releasing molecules and the efforts to detect CO for biological applications

•CO is associated with a variety of physiological roles and therapeutic applications.•Carbon monoxide releasing molecules deliver CO in a controlled and directed fashion.•An assortment of metal carbonyls shows promise as PhotoCORMs.•The ability to selectively detect CO is crucial, and techniques are discussed.

Several beneficial biological effects of carbon monoxide (CO) have been identified. CO contributes to vascular tone, is anti-inflammatory and antiapoptotic, and protects tissue against hypoxia. In response, a number of novel CO-releasing systems, mostly transition-metal carbonyl compounds, have been reported. Recent research in the area of photochemical CO-releasing molecules (PhotoCORMs) is reviewed. The photophysical and chemical properties of these PhotoCORMs are described, along with studies of biological activity in some cases. Spectral data and quantum yields, when available, are compared. In addition, various methods for the detection and quantification of CO are discussed.