AbstractGiven a graph G, the Mostar index Mo(G) is the sum of absolute values of the differences between nu(e) and nv(e) over all edges e = uv of G, where nu(e) and nv(e) are, respectively, the number of vertices of G lying closer to u than to v and the number of vertices of G lying closer to v than to u. A tree‐like polyphenyl is a polycyclic aromatic hydrocarbon consisting of benzene rings, whose chemical graph will tend to a tree after contracting each hexagon into a vertex (the tree is called a contracted tree). A polyphenyl chain is a tre...