Polymorphism of inclusion complexes and unsolvated hosts .1. Trimorphism of the host-guest complex of gossypol with dichloromethane. The structure of the beta-phase

The formation of host-guest complexes of gossypol at different temperatures has been investigated for the same pressure and concentration. Gossypol forms three different clathrates with dichloromethane within the temperature interval of 22-36 degrees C. Single crystals of these three modifications (phases) were obtained and their crystallographic parameters measured. The structure of the alpha-phase has been determined previously and the gamma-phase is isostructural to the inclusion complex of gossypol with benzene, while the structure of the beta-phase has been solved during the present research. Crystals of C30H30O8 . CH2Cl2 are triclinic, space group P (1) over bar, a = 8.604(1), b = 11.858(2), c = 14.405(2) (Angstrom), alpha = 84.60(1), beta = 89.14(1), gamma = 89.73(1)degrees, V = 1463(1) Angstrom(3), Z = 2, R = 0.089 for 2419 observed reflections. Under ambient conditions gossypol forms unstable tubulates of the alpha-phase; the gamma-phase is a stable cage-type clathrate (cryptate) and the host-guest complex of the beta-phase is a clathrate of intermediate tubulato-cryptate type.