Structural aspects of a commensurate tunnel inclusion compound of tri- ortho-thymotide containing 1,8-dibromooctane guest molecules

Abstract

Structural properties of the solid inclusion compound formed between 1,8-dibromooctane and tri- ortho-thymotide (TOT) are reported. In contrast to the inclusion compounds formed between TOT and other long-chain α,ω-dihalogenoalkane guest molecules, the 1,8-dibromooctane/TOT inclusion compound has a commensurate relationship between the host and guest subsystems. The structural properties of this inclusion compound have been investigated at ambient temperature (293 K) and 123 K using single crystal X-ray diffraction techniques. At both temperatures, the structure [space group P6 1 (P6 5)] is based on a superstructure (with seven-fold increase in unit cell volume) of the standard type T-II host structure of TOT inclusion compounds. The superstructure represents a comparatively small distortion from the standard type T-II TOT host structure, and contains two independent types of tunnels (the central and non-central tunnels). At 123 K, the guest molecules in the non-central tunnels are ordered (although with conformational disorder of the bromine end-groups), whereas the guest molecules in the central tunnel are disordered. At 293 K, there is substantial disorder of the guest molecules in both the central and non-central tunnels. The structural properties of 1,8-dibromooctane/TOT contrast with those of other α,ω-dihalogenoalkane/TOT inclusion compounds.