Photochemical Hydroxyl Group Abstraction from N -Hydroxypyridine-2(1 H )-thione Isolated in a Solid Hydrogen Matrix: Photogeneration of 2-Mercaptopyridine

• Published in: Molecules (Basel, Switzerland) Switzerland), 2024-11, Vol.29 (22), p.5472
• Main Authors: Rostkowska, Hanna, Nowak, Maciej J, Reva, Igor, Lapinski, Leszek
• Format: Article
• Language: English
• Subjects: 2-mercaptopyridine-N-oxide; cage effect; Hydrogen; hydroxyl radical; IR spectra; photochemistry; reactive matrix
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29225472

Monomers of -hydroxypyridine-2(1 )-thione were isolated in low-temperature matrices of solid normal hydrogen (n-H ). The matrix-isolated compound was irradiated with UV-B (λ = 305 nm) or UV-A (λ > 360 nm) light. Upon such irradiation, the initial form of -hydroxypyridine-2(1 )-thione was completely consumed and converted into photoproducts. 2-Mercaptopyridine and water were identified as the main products of these photochemical transformations. Identification of photoproduced 2-mercaptopyridine is unquestionable. It is based on the identity of two sets of IR bands: (i) the bands observed in the IR spectrum recorded (in a separate experiment) for monomers of 2-mercaptopyridine trapped in an n-H matrix and (ii) a set of IR bands observed in the spectrum recorded after UV irradiation of -hydroxypyridine-2(1 )-thione. It should be emphasized that the UV-induced processes, occurring for -hydroxypyridine-2(1 )-thione isolated in an n-H matrix, lead to products that are significantly different from those generated from the compound trapped in solid Ar or in solid N .