Topological characterization of large benzenoid hydrocarbon systems and their chemical significance

Chemical graph theory is an important branch of graph theory with significant applications in chemistry. Topological indices, which are numerical quantities associated with molecular graphs, play a central role in modeling chemical and physical properties in quantitative structure–property relationship (QSPR) and quantitative structure-activity relationship (QSAR) studies. In this paper, we compute several classical, modified, and multiplicative topological measures for the hexabenzocoronene, hexa-cata-hexabenzocoronene, and dodeca-benzo-circumcoronene benzenoid systems. In addition, we investigate the corresponding entropies and related generating functions of these molecular graphs. A comparative analysis is established for the principal additive descriptors, while the multiplicative descriptors are compared with respect to the proven minimum family and their asymptotic behavior. The resulting closed forms quantify structural differences among the three benzenoid families and provide candidate graph-theoretical inputs for future QSPR/QSAR investigations; no direct property-prediction model is fitted in the present study.