Yoon Hojeong, Park Seongchul, Kim So Yeon, Hong Daewha, Park Jae Woo, Lim Manho
Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea.
Korea Institute for Future Earth, Pusan National University, Busan 46241, Korea.
J Phys Chem Lett. 2024 Aug 29;15(34):8829-8837. doi: 10.1021/acs.jpclett.4c02175. Epub 2024 Aug 21.
Understanding the photodynamics of S-nitroso-thiol (RSNO), an effective NO transporter in biological systems, is essential for its photochemical applications. S-nitroso-mercaptoethanol (MceSNO), a simple water-soluble RSNO, facilitates high-level quantum calculations. We investigated the photoexcitation dynamics of MceSNO in an aqueous solution, focusing on NO dissociation, recombination, and linkage isomerization using quantum calculations and femtosecond infrared spectroscopy. Upon excitation at 320 nm, MceSNO rapidly dissociates into NO and MceS radicals. Approximately 31 ± 3% of MceS reacts with unexcited MceSNO molecules, forming MceSSMce and releasing additional NO. The remaining MceS undergoes geminate recombination with NO, forming either MceSNO (41 ± 4%) or MceSON (28 ± 3%), the latter being a sulfur-ON linkage isomer observed for the first time in a room-temperature solution. MceSON isomerizes back to MceSNO in 470 ± 30 ps. The formation mechanism of MceSON was verified through a potential energy surface constructed at the CASPT2D(16,11)/cc-pVTZ level. The isomerization barrier was determined to be 3.3 ± 1.2 kcal/mol in water.
了解生物系统中有效的一氧化氮转运体S-亚硝基硫醇（RSNO）的光动力学，对其光化学应用至关重要。S-亚硝基巯基乙醇（MceSNO）是一种简单的水溶性RSNO，有助于进行高水平的量子计算。我们研究了MceSNO在水溶液中的光激发动力学，利用量子计算和飞秒红外光谱重点研究了NO的解离、重组和键异构化。在320nm激发时，MceSNO迅速解离为NO和MceS自由基。约31±3%的MceS与未激发的MceSNO分子反应，形成MceSSMce并释放出额外的NO。其余的MceS与NO发生双分子重组，形成MceSNO（41±4%）或MceSON（28±3%），后者是首次在室温溶液中观察到的硫-ON键异构体。MceSON在470±30ps内异构化为MceSNO。通过在CASPT2D(16,11)/cc-pVTZ水平构建的势能面验证了MceSON的形成机制。在水中确定异构化势垒为3.3±1.2kcal/mol。
