Caged Nitric Oxide–Thiyl Radical Pairs
Zhuang Wu†⊥, Changyun Chen†⊥, Jie Liu†, Yan Lu†, Jian Xu†, Xiangyang Liu‡, Ganglong Cui*‡（崔刚龙）, Tarek Trabelsi§, Joseph S. Francisco*§, Artur Mardyukov#, André K. Eckhardt#, Peter R. Schreiner#, and Xiaoqing Zeng*†（曾小庆）
†College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
‡Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
§Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
#Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
⊥Z.W. and C.Y.C. contributed equally to this work.
J. Am. Chem. Soc., 2019, 141 (8), 3361--3365
S-Nitrosothiols (RSNO) are exogenous and endogenous sources of nitric oxide in biological systems due to facile homolytic cleavage of the S–N bonds. By following the photolytic decomposition of prototypical RSNO (R = Me and Et) in Ne, Ar, and N2 matrixes (<10 K), elusive caged radical pairs consisting of nitric oxide (NO•) and thiyl radicals (RS•), bridged by O···S and H···N connections, were identified with IR and UV/vis spectroscopy. Upon red-light irradiation, both caged radical pairs (RS•···•ON) vanish and reform RSNO. According to the calculation at the CASPT2(10,8)/cc-pVDZ level (298.15 K), the dissociation energy of MeS•···•ON amounts to 4.7 kcal mol–1.