Theoretical Study on Intramolecular Proton Transfer Reaction in 2-(2-Mercaptophenyl)benzoxazole

在b3lyP/6-31g(d,P)水平上研究了2-(2-巯苯基)苯并噁唑气态中五种异构体(E1,E2,E3,E4和k)在气态中的稳定性及其在基态下的质子转移,同时结合极化连续介质模型(PCM)研究了水、二甲亚砜、乙腈、乙醇、苯胺和环己烷等对2-(2-巯苯基)苯并噁唑溶剂化作用的影响.研究结果表明,醇式异构体E1为2-(2-巯苯基)苯并噁唑的优势构型;在E1向k(酮式异构体)转变过程中,存在一个较小的能垒;当考虑零点振动能(zPVE)后,逆向能垒消失.在溶液中,随着溶剂极性的增强,醇式异构体E1与k之间的反应平衡向k方向移动,在非极性溶剂环己烷中,E1为优势构型,而在强极性水溶液中,k为优势构型。The tautomers(E1,E2,E3,E4,and K) and the ground state intramolecular proton transfer reaction of 2-(2-mercaptophenyl)benzoxazole were studied at the B3LYP/6-31G(d,p) level.The effect of solvent(water,dimethylsulfoxide,acetonitrile,ethanol,aniline,and cyclohexane) was studied at the B3LYP/6-31G(d,p) level,using the polarizable continuum model.The results of density functional calculations indicate that the enol form E1 is the most stable tautomer at the ground state.In these solvents there is an equilibrium for 2-(2-mercaptophenyl)benzoxazole in the ground state between E1 and K,and the equilibrium shifts toward the tautomer K as the polarity of the solvent increases.E1 is the preferential conformation in cyclohexane,but K is the more stable tautomer in water.国家自然科学基金(Nos.20772027;20803020);973子课题(No.2003CB716005);中国博士后科学基金(No.20070410805)资助项

NMR Studies on Interactions between Diperoxovanadate and N-Substituted Picolinamide

为了探讨有机配体上取代基团对反应平衡的影响,在模拟生理条件下(0.15mol/LNaCl溶液),应用多核(1H,13C和51V)多维(COSY和DOSY)NMR以及变温技术等谱学方法研究双过氧钒配合物[OV(O2)2(D2O)]-/[OV(O2)2(HOD)]-与N-取代皮考啉酰胺的相互作用.它们反应性从强到弱的顺序为:N-甲基-皮考啉酰胺≈N-(2-羟乙基)-皮考啉酰胺>N-乙基-皮考啉酰胺>N-丙基-皮考啉酰胺,这说明了皮考啉酰胺N上取代基的电子效应影响反应.竞争配位导致一系列新的7配位的过氧钒物种生成,而利用上述谱学方法则有助于揭示此类相互作用体系的反应过程和配位机制.To understand the substituting effects of organic ligands on the reaction equilibrium, the interac- tions between diperoxovanadate complex [OV(O2)2(D2O)]-/[OV(O2)2(HOD)]- and a series of N-substituted picolinamide ligands in solution were explored using multinuclear (1H, 13C, and 51V) magnetic resonance, COSY, DOSY, and variable temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physio- logical conditions. The order of reactive capability of the picolinamide-like ligands with [OV(O2)2(D2O)]-/ [OV(O2)2(HOD)]? is as follows: N-methylpicolinamide ≈ N-(2-hydroxyethyl)picolinamide > N-ethyl- picolinamide>N-propylpicolinamide. The substituting group influences the reactivity by an electron effect. Competitive coordination interactions result in a series of new seven-coordinated peroxovanadate species [OV(O2)2L]-(L=N-substituted picolinamide).973子课题(No.2003CB716005);; 国家自然科学基金(No.20772027);; 湖南省自然科学基金(No.06JJ30004);; 中国博士后科学基金(No.20070410805);; 卫生部(福建省)卫生教育联合攻关计划(No.3502Z20051027);; 厦门市重大疾病攻关研究基金(No.Wkj2005-2-019);; 固体表面物理化学国家重点实验室开放基金;; 湖南科技大学博士基金(No.E-55107)资助项目

NMR studies on interactions between diperoxovanadate and N-substituted picolinamide

To understand the substituting effects of organic ligands on the reaction equilibrium, the interactions between diperoxovanadate complex [OV(O-2)(2)(D2O)(-)/[OV(O-2)(2)(HOD)](-) and a series of N-substituted picolinamide ligands in solution were explored using multinuclear (H-1, C-13, and V-51) magnetic resonance, COSY, DOSY, and variable temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physiological conditions. The order of reactive capability of the picolinamide-like ligands with [OV(O-2)(2)(D2O)](-)/[OV(O-2)(2)(HOD)](-) is as follows: N-methylpicolinamide approximate to N-(2-hydroxyethyl)picolinamide > N-ethylpicolinamide>N-propylpicolinamide. The substituting group influences the reactivity by an electron effect. Competitive coordination interactions result in a series of new seven-coordinated peroxovanadate species [OV(O-2)(2)L](-) (L=N-substituted picolinamide)