The use of topological indices to predict thermodynamic properties of amino acid derivatives

In the present investigation the applicability of various topological indices are tested for the QSPR study on 80 amino acid derivatives. Relationship between the Randic (1X), Balaban (J), Szeged (Sz), Harary (H), Wiener (W), Hyper-Wiener (WW) and Wiener Polarity (Wp) indices to the thermodynamic properties such as thermal energy Eth (J/mol) and heat capacity (CV J/mol. K) of amino acids is represented. The thermodynamic properties are taken from HF level using the ab initio 6-31G basis sets from the program package Gaussian 98. We have used Multiple Linear Regression (MLR) techniques and followed back ward regression analysis for obtaining properties. By analyzing the correlation between the indices in the made models, the most suitable indicators for modeling properties were determined. The predictive powers of the models were discussed using leave-one-out (LOO) cross-validation. The obtained results show that combining of the two descriptors (J, 1X) could be used successfully for modeling and predicting the heat capacity (CV), and thermal energy (Eth) of amino acid derivatives.