Non-hydroxylic clathrate hosts of [4 + 2]π cycloadducts of phencyclone and N-arylmaleimides: recognition of aromatic guests

Abstract

A series of non-hydroxylic crystalline host compounds, [4 + 2]π cycloadducts of phencyclone and N-arylmaleimides having a bicyclo[2.2.1]heptene-7-one system, was synthesized and their inclusion behavior investigated. X-Ray crystal analyses of the inclusion compounds of the N-(1-naphthyl) derivative with butan-2-one, the N-(m-tolyl) derivative with p-xylene, together with the guest-free host and the N-(p-tolyl) derivative with m-xylene indicate that the “space” surrounded by the phenanthrene ring, two phenyl rings and bridge carbonyl of the 1,3-diphenyl-1,3-dihydrocyclopenta[l]phenanthren-2-one moiety plays an important role, not only in the formation of inclusion complexes with the aromatic guests but also in host–host interactions. In every case, the N-aryl succinimide assists complex formation with the guests, in which the weak lattice forces due to C–H⋯π and C–H⋯O interactions are operative. Methyl-substituted benzenes are effectively recognized by the C–H⋯π interactions between the guest molecules and the phenanthrene ring of the hosts.