Reactivity of visible-light induced CO releasing thiourea-based Mn(I) tricarbonyl bromide (CORM-NS1) towards lysozyme

The synthesis of visible-light induced carbon monoxide releasing complexes (photoCORMs) with some perquisites such as solubility in water or in a medium suitable for drug delivery (H2O/DMSO), dark stability under the aerated conditions and CO releasing upon the illumination, is the major challenge for the phototherapeutic CO applications. The reaction of N-(2-thiazoly1)-1H-benzotriazole-1-carbothioamide (HL) with [MnBr(CO)5] affords fac-[MnBr(CO)(3)(HL)] (CORM-NS1). The aerated DMSO solution of CORM-NS1 is stable for 16 h. The process of the photo induced CO release is studied using two excitation wavelengths, 468 and 525 nm and quantitatively estimated by the myoglobin assay and commercial gas sensor. The electronic structure of CORM-NS1 is calculated at PCM/TD-B3LYP/def2-SVP (or LANL2DZ) level of theory. Interaction of CORM-NS1 with hen egg white lysozyme (HEWL), as a biocompatible carrier, is studied in the dark and upon illumination by means of ESI-MS. In the dark, an adduct peak corresponding to binding of Mn(CO)(3) fragment to HEWL is observed, which disappears upon the illumination with either the green or blue light