4,4’-二苯甲酰基联苯构象的分子力学研究

4,4’—二苯甲酰基联苯有两个三岔点,属于二元三岔共轭体系。从结构式上看,卽可把它作为二苯甲酮骨架的取代产物,又可看作是在联苯骨架上的取代。作为系统研究三岔共轭体系结构效应的部分工作,我们用QCFF/PI+MCA(Quantum Mechanical Extension of the Consistent Force Field to PI Electron System+Molecular Crystal Analysis)程序研究了其晶态和孤立态(气态)构象。研究结果表明,在孤立态中,联苯基的二个苯环的最小二乘

MOLECULAR MACHANICS STUDY ON THE CONFORMATION OF 4,4'-DIBENZOYLBIPHENYL

The conformations of title compound in the crystal and in the isolated state have been calculated by means of QCFF/PI+MCA (Quantum Mechanical Extension of the Consistent Force Field to PI Electron System+Molecular Crystal Analysis) computer program. The results of investigation indicated that the twist angle between the two phenyl rings of biphenyl in the molecule is about 18.9° in the gas phase and 1.3° in the crystalline phase. The conformation of the molecule in the crystal is in agreement with that obtained by X-ray crystal structure determination. We have calculated equilibrium geometries and vibrational frequencies of 4,4'-diben-zoylbiphenyl. The observed and some calculated vibrational frequencies are listed in Table 1.