Inclusion of Nonopiate Analgesic Drugs in Cyclodextrins. I. X-Ray Structure of a 1 : 1 β-Cyclodextrin-p-bromoacetanilide Complex

Abstract

The preparation and X-ray crystal structure of a 1 : 1 complex between β-cyclodextrin (β-CD) and the analgesic p-bromoacetanilide are reported. Thermogravimetric and UV spectrophotometric analyses of single crystals grown from an aqueous solution containing host and guest in 1 : 1 molar ratio yielded the composition β-CD ċ p-bromoacetanilide ċ$ 13.5H2O. Crystals of the complex are triclinic, space group P1, with a = 15.197(3), b = 15.613(2), c = 15.743(4) Å, α = 87.16(2), β = 98.29(2), γ = 103.39(1)° and Z = 2 crystallographically independent complex units per unit cell. The β-CD molecules form head-to-head dimers which pack in the channel-mode. Each dimer contains two guest molecules whose acetylamino substituents are located at the dimer interface while the bromine atoms protrude from the β-CD primary faces. The acetyl residues of both guest molecules were found to be disordered but the X-ray data permitted