Application of quantum chemical descriptor in quantitative structure activity and structure property relationship

Various quantum chemical descriptors such as ionisation potential (I), electron affinity (A), quantum chemical hardness index (η), softness index (S), electronegativity (χ) and electrophilicity (ω) have been used in order to develop a possible quantitative structure–activity and structure–property relationship (QSAR/QSPR) model for a series of alkanes. The correlation between `Iʹ and boiling point (BP) of alkanes (C2–C8) has been found to be −0.984. Among the six selected descriptors, linear relations derived from `Iʹ reproduce fairly better experimental values for all the selected macroscopic properties. Hardness and softness indices exhibit acceptable correlation for all the selected macroscopic properties. They show promising correlation for heat of formation thereby establishing the fact that hardness is a measure of stability of molecules.