S-亚硝基-N-乙酰基-D,L-青霉胺二肽分子中S—NO键断裂能的测定

利用滴定量热技术并结合适当的热力学循环测定了乙腈溶液中7个S-亚硝基-N-乙酰基-D,L-青霉胺二肽化合物中S—NO键的异裂能和均裂能, 其能量范围分别为234.5—246.2 kJ/mol和101.6—122.1 kJ/mol. 结果表明, 所研究的亚硝基硫醇化合物更容易通过S—NO键的均裂释放NO自由基(NO·). 通过热力学循环对7个亚硝基硫醇化合物自由基负离子中S—NO键的异裂能和均裂能进行估算, 能量范围分别为19.2—35.5 kJ/mol和-4.2—22.6 kJ/mol, 表明这些自由基负离子在室温下不稳定, 容易通过S—NO键的异裂释放出NO-.

Determination of S-NO Bond Dissociation Energies of S-Nitroso-N-acetyl-D,L-penicillamine Dipeptides

S-Nitrosodipeptides are generally believed to be good NO donors, and many NO-related biological functions have been directly associated with S-nitrosodipeptides, especially in the processes of NO-storage, transport and delivery. In this work, the heterolytic and homolytic S—NO bond dissociation energies of seven S-nitrosodipeptides were evaluated via titration calorimetry and relative thermodynamic cycles. The energetic scales of the heterolytic and homolytic S—NO bond dissociation energies of these RSNOs covered the ranges 234.5—246.2 and 101.6—122.1 kJ/mol, respectively, which indicated that the studied S-nitrosodipeptides were much easier to release a NO radical(NO·) rather than a NO cation(NO+). The estimation of the heterolytic and homolytic(S—NO)-· bond dissociation energies of the S-nitrosodipeptides radical anions gave the energetic ranges of 19.2—35.5 and 4.2—22.6 kJ/mol for the(S—NO)-· bond homolysis and heterolysis, respectively, which meant that S-nitrosodipeptides radical anions were unstable at room temperature and favored to releasing a NO anion(NO-) by heterolysis cleavage.