机构地区: 南开大学
出 处: 《高等学校化学学报》 2008年第8期1569-1572,共4页
摘 要: 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234.5~246.2kJ/mol和101.6~122.1kJ/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19.2~35.5kJ/mol和~4.2~22.6kJ/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^-. 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 heter- olytic 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.