A Modified Distance Matrix to Distinguish Cis/Trans Isomers

The general distance matrix D was modified to distinguish cis/trans isomers of cycloalkanes. A new topological index, VDI(±1), was derived from the modified distance matrix (Dmod) according to the calculation of VDI proposed in a previous paper. This new structural descriptor discriminates all compounds studied in this paper. The regression analysis against the boiling temperatures (tb) for 53 cis/trans isomers of cycloalkanes with VDI(±1) and other topological indices gives a high correlation coefficient (r = 0.9961) and low standard deviation (s = 3.31 ºC), which is much better than that obtained with VDI(0). Keywords. Topological index; boiling temperature; quantitative structure–property relationships; QSPR; molecular graph; structural descriptor; distance matrix.