THE CRYSTAL-STRUCTURE OF THE INCLUSION COMPLEX OF CYCLOMALTOHEPTAOSE (BETA-CYCLODEXTRIN) WITH 3,5-DIMETHYLBENZOIC ACID

The crystal of the betaCD-3,5-dimethylbenzoic acid inclusion complex i s triclinic P1 with a = 15.707(3), b = 15.694(3), c = 15.999(3) angstr om, alpha = 101.502(5), beta = 101.557(5), gamma = 103.805(4)-degrees, V = 3624 angstrom3, and Z = 1. Two crystallographically independent b etaCD molecules form a dimer by means of hydrogen bonds between second ary hydroxyl groups in which disordered guest molecules in six orienta tions are accommodated. In two of them the guest molecules are situate d at the dimer interface, their carboxyl groups interacting with the c arboxyl groups of two other guest orientations that are found on eithe r side of the monomer cavity. In the two last orientations the guest m olecules enter the monomer cavities in an opposite sense with the carb oxyl groups protruding from the primary side and are stabilized by cyc lodextrin hydroxyl groups. A dense water network is formed in the inte rdimer space consisted of 18.2 water molecules distributed over 24 sit es.