头孢克肟的量子化学密度泛函计算研究

Quantum Chemistry Density Functional Calculation Research of Cefixime

择选量子化学密度泛函方法,在6-311+g(d,p)基组水平上,结合水为PCM溶剂模型,对抗生素药物头孢克肟进行了计算研究。结果表明:分子中存在的多元环并非活性部位,C^7=N^8和N^8=O^9键部位是分子活性中心,带明显的正电性,易接受亲核试剂进攻;分子频率振动以2823.24cm^-1处的四元环摆动与C=O键伸缩振动叠加为主,其结果与实验光谱一致;热力学计算表明298.15K时标准生成吉布斯自由能变为-2.24kcal·mol^-1,低温有利于它的合成。

On the basis level of 6-311+g(d,p),we have done much calculated work for the cefixime molecule combined the PCM solvent model by the density functional method in the quantum chemistry(the water is the solvent).The results show that there are many rings in this molecule but they are not the molecular active center,while C^7=N^8 and N^8-O^9 bond sites are the active centers of molecules with obvious positive properties,which are easy to be attacked by nucleophilc reagent.The maximum peak is displayed at the 2823.24 cm-1,which is ascribed to the flutter of four atoms ring and stretching vibration of the bond of C=0,and all the analysis result is in agreement with the experimental infrared spectrum.The thermodynamics properties calculation is done at the same level and method,and the normal gibbs free formation energy is-2.24 kcal·mol-1 at 298.15 K,which also indicates that the lower temperature is helpful to the synthesis of cefixime.