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Updated: Jun 15, 2025

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
Dynamics of NO Release and Linkage Isomer Formation from S-Nitroso-Mercaptoethanol in Aqueous Solutions: Insights
Hojeong Yoon1, Seongchul Park1,2, So Yeon Kim3
1Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea.
Abstract:
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.
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