LEL-a Newly Designed Molecular Descriptor

A correlating study of topological indices TIs provided by TOPOCLUJ software package and LEL, a newly proposed index built up on the eigenvalues of Laplacian matrix, on thirteen properties of octanes, revealed good correlating ability of a dozen selected TIs, all related to the Wiener index, and of LEL as well. LEL describes well the properties which are well accounted by the majority of the selected molecular descriptors: octane number MON, entropy S, volume MV, or refraction MR, particularly the acentric factor AF parameter, but also more difficult properties like boiling point, melting point and logP. LEL is the best correlated with the WK (Wiener-type number, taken the reciprocal of entries in the combinatorial Dp matrix, of higher rank, calculated by TOPOCLUJ software) indices. In a second set of polycyclic aromatic hydrocarbons, LEL was proved to be as good as the Randi} Xindex (a connectivity index) and better than the Wiener index (a distance based index). In addition, it is well defined mathematically and shows interesting relations in particular classes of graphs, these recommending LEL as a new, powerful topological index. The actual study proved the considered TIs are basic topological descriptors in prediction of various molecular properties, with good perspective in QSPR/QSAR studies.