Force field calculations on molecular belts built from cyclohexa-1,4-diene rings

Abstract

Calculations using the MM2 program are reported on a series of hydrocarbons constructed by lateral fusion of n cyclohexa-1,4-diene rings, the [n]beltenes. Strain energy per macro-ring unit (–CH₂[graphic omitted]CH₂–) decreases monotonically from [3]beltene to [12]beltene. The beltenes have the shape of a semi-rigid molecular torus, the larger beltenes containing a substantial cavity. Encapsulation of acetylene becomes favourable with [8]beltene. The encapsulation of some other small molecules has been examined. The shape and strain energy of selected hydrogenated beltenes is discussed.