提出键参数f_i,在此基础上定义分子键连接性指数F=sum from i=1 to m(f_i)^(1/2)。考虑到氯原子的个数和位置的影响,引入距离指数L将F修正,得到修正的连接性指数F_X=F+L^(-.5)。F_X具有很强的结构选择性,且与多氯代二苯并呋喃(PCDFs)在不同色柱上(DB-5,SE-54,OV-101)气相色谱保留指数(RI)和保留时间(RRT)具有良好的相关性。用该模型预测了135个PCDFs化合物的色谱保留数据,预测能力优于文献。该模型还具有物理意义明确,计算简便的优点。
The orientation indices and group corresponding indices of 210 molecular structures of polychlorinated biphenyls(PCBs)and biphenyl were calculated.By combining these indices with seven thermodynamic properties reported in literature of such PCBs, including standard entropy (S0),standard enthalpy(H0),standard free energy(G0),total energy(ET),thermal energy correction(Eth),zero-point vibration energy(Ezpv)and constant volume molar heat capacity (C0V), a series of quantitative structure property relationship (QSPR) equations were built up by the multiple regression method.All the correlation coefficients were larger than 0.99.These models could better explain the change of thermodynamic properties for the PCBs,and the QSPR models had high correlation coefficients,good stability and good predictability.A modified leave-one-out procedure test was performed to validate model robustness,and predict the S0,H0,G0,ET,Eth,Ezpv,C0V of other PCBs molecules by the regression equation,and the error analysis were discussed.The results showed better agreement between the values predicted by the model developed and the observed values of the thermodynamic properties.
