Rapid green and blue light-induced CO release from bromazepam Mn(I) and Ru(II) carbonyls: synthesis, density functional theory and biological activity evaluation

Two new photoactivatable carbon monoxide-releasing molecules (CORMs), fac-[Mn(CO)₃(BZM)Br] (1) and [RuCl₂(BZM)(CO)₂] (2), derived from the anti-anxiety drug bromazepam (BZM) and capable of rapid release of CO upon the illumination with light-emitting diode (LED) source light (470–525 nm) have been synthesized and characterized. The photo-delivery of CO to myoglobin solution could be achieved via the illumination of 1 at 525 nm for 10 min or at 470 nm for 1 min. The addition of water to a dimethylsulfoxide (DMSO) solution of 1 increases its stability, but it decreases the rate of the CO-releasing process. CORM 2 behaves as a good visible photoCORM, whereby its two CO molecules are released within 10 min upon exposure to LED light source at 470 nm in DMSO. The illumination profile of 2 was also examined using solution infrared spectroscopy. The cis/trans stereochemistry around the Ru(II) ion was determined using quantum chemical calculations. The formation of photoCORMs leads to an improvement in the toxicity of BZM against tested microbes.