Quantum topological method studies on the thermodynamic properties of polychlorinated phenoxazines

• Novel quantum topological indices PY1,2 derived from molecular structure.
• Quantum topological method on quantitative structure–property relationships of Phx and 135 PCPXs.
• Model is statistically significant and shows good stability for data variation tested by leave-one-out cross-validation.

The novel quantum topological indices PY1,2 were derived from molecular structure combined with the effect of atom space, the character of bonding atoms (such as equilibrium electro-negativity) and the branching effect between the atoms. The quantitative structure–property relationships (QSPRs) were proposed between PY1,2 and the thermodynamic properties (△fHθ, △fGθ   and ΔfGRθ) of phenoxazine (Phx) and 135 kinds of polychlorinated phenoxazines (PCPXs), by Multiple linear regression (MLR) analysis method. The high-quality prediction models were evidenced by the correlation coefficient R, the standard error of estimate S, the Fisher statistic value and the cross-validated correlation coefficient RCV. With the new QSPR model, we are able to predict a wide range of thermodynamic properties of an extensive number of molecules. And the model is statistically significant and shows good stability for data variation as tested by the leave-one-out cross-validation (LOO-CV).