对羧基苯甲醛缩-2-噻吩甲酰腙的合成、结构及量子化学计算

摘要

A new compound of 4-( (2-thiophenecarboxylic acid hydrazide) methylene) benzoic acid was synthesized by the reaction of ethyl 2-thiophenecarboxylate,hydrazine hydrate and 4-formylbenzoic acid,and characterized by elemental analysis,IR,UV and X-ray diffraction methods.The compound forms a 3-D network through intermolecular N-H…O and O-H…O hydrogen bondings.The dihedral angle between the benzene and thiophene ring is 14.9°.The title compound has intense purple emission at 396 nm when excited at 286 nm.The result of TG/DTG analysis showed that the title compound was stable below 298℃ in N2.The quantum chemical calculation was performed by means of Gaussian 03 W program.The Mulliken charge population and Wiberg bond order of the compound and its frontier molecular orbital energy have been discussed.Furthermore,we analyzed its active atoms and evaluated its reliability.The results showed that the values of the bond lengths and bond angles of the quantum chemical calculation were almost the same with the values of X-ray diffraction.The difference between the two methods confirmed the presence of intermolecular hydrogen bonds in their crystal structures.The carbonyl groups are the active centers.%以2-噻吩甲酸乙酯、水合肼和对醛基苯甲酸为原料合成了对羧基苯甲醛缩-2-噻吩甲酰腙.通过元素分析、IR、UV和X射线单晶衍射对化合物结构进行了表征.晶体中化合物分子间由弱的N—H…O、O—H…O氢键作用形成三维网状结构.分子中噻吩环平面和苯环平面之间的夹角为14.9°.发光性质显示,化合物在396 nm处有强的紫外发射峰(激发波长为286 nm).热分析表明,化合物在298℃下比较稳定.依据晶体结构数据使用Gaussian 03W程序对化合物进行了量子化学计算,分析了化合物分子轨道能量、原子净电荷布居和成键特征,分析了化合物分子反应活性、选择性和稳定性.计算的分子键长、键角与X射线衍射晶体结构数据基本符合,其差值证实晶体中分子间存在氢键,化合物中的羰基是主要的活性中心.