On the Maximal Mostar Index of Tree-Type Phenylenes.

In organic chemistry (especially in polycyclic aromatic compounds), hexagonal and quadrilateral molecular structures are very common. Let P h be the set of phenyenes with h hexagons and h − 1 quadrilaterals. The Mostar index Mo(G) is defined as M o (G) = ∑ e = u v ∈ E (G) | n u − n v | , where nu (resp., nv) is the number of vertices whose distance to vertex u (resp., v) is smaller than the distance to vertex v (resp., u). In this paper, we completely determine the maximal values of the Mostar index of tree-type phenylenes with one full-hexagon and characterize all the tree-type phenylenes attaining these values. Moreover, we give some properties of tree-type phenylenes with maximal Mostar index. [ABSTRACT FROM AUTHOR]