Parabolic Reactivity “Coloring” Molecular Topology: Application to Carcinogenic PAHs

The ability to derive colored representations of widely employed distance-based topological indices from chemical reactivity electronegativity and chemical hardness has been developed in the novel theoretical tool presented in this work to provide novel, meaningful topo-reactive or structure-reactivity indices with application to polycyclic aromatic hydrocarbons (PAHs). The model, which combines topological and ab initio molecular structural information, relies on the so-called Timisoara-Parma rule for assigning the axial distribution of electronegativity and chemical hardness to a given molecular structure based on a compact finite-difference (CFD) hierarchy, which involves ordering nine forms of electronegativity and chemical hardness derivative-based definitions within conceptual density functional theory (DFT). The results are in good agreement with theoretical and experimental properties improving the predictive power of standard topological indices. The proposed method is suitable for molecular structures with delocalized electrons.