Computational chemistry as applied to polymerization reactions and biological systems

The cationic homopolymerization reactions of expanding and potentially expanding monomer systems were modeled and the energies of activation were calculated using the AM1 semiempirical quantum mechanical method. The results were used to determine the relative reactivity of study monomers with respect to spiro-orthocarbonates (SOC) and epoxides. All expanding monomers studied were endothermic by 4–16 kcal/mole except the methylated bicyclic orthoesters which had an enthalpy of reaction of essentially 0 kcal/mole. Three potentially expanding monomers were exothennic by 3–18 kcal/mole. The energies of activation for all expanding monomers ranged from 28–37 kcal/mole.; Geometries for 62 phosphatidylcholines (PC) were optimized using the AM1 semiempirical quantum mechanical method. Results obtained from these calculations were used to calculate 463 descriptors for each molecule. Quantitative Structure Property Relationships (QSPR) were developed from these descriptors to predict chain melting temperatures (T_m) for the 41 PCs in the training set. After screening each QSPR for statistical validity, the T_m values predicted by each statistically valid QSPR were compared to corresponding T_m values extracted from the literature. The most predictive, chemically meaningful QSPR provided T_m values which agreed with literature values to within experimental error. This QSPR was used to predict T _m values for the remaining 21 PCs to provide external validation for the model. These values also agreed with literature values to within experimental error.; Detailed high quality experimental data for 127 molecules were collected from literature accounts and commercial sources. These molecules were then separated into a training set and a test set whereupon the geometries for the study compounds were optimized and characterized using the SAM1 quantum mechanical semiempirical method. Result files from those calculations were incorporated into the development of four QSPRs, a general QSPR encompassing all training set molecules, and three major subgroup QSPRs. The general correlation had an R2 value of 0.944 and an average unsigned residual error of 1.7 mM. The saccharide, phospholipid and alcohol correlations had R 2 values of 0.948, 0.938, and 0.907 respectively, with average unsigned residual errors of 1.7 mM, 1.9 mM, and 2.2 mM respectively.