Algebraic structure count of liner phenylenes and their congeners

Abstract

The algebraic structure count of the linear phenylene with h six-membered rings is known to be equal to h + 1. We show that the same expression applies if each four-membered ring in the phenylene is replaced by a linear array consisting of k four-membered rings, where k = 4, 7, 10,... For any other value of k, the algebraic structure count is either 0 or 1 or 2, and does not increase with increasing h.