Inclusion complexes of the natural product gossypol. Crystal structures of gossypol complexes with benzene and chloroform as guests

Abstract

The crystal structures of the lattice inclusion complexes of gossypol with benzene and chloroform have been determined by X-ray structure analysis. The crystals of (C₃₀H₃₀O₈)₂ · C₆H₆ (GPBNZ) are triclinic, space groupPI,a = 11.241(3),b = 14.986(4),c = 17.380(4) Å, α = 98.89(2), β = 99.86(2), γ = 98.91(2)°,V = 2800(2) ų,Z = 2,D _x = 1.32 g cm⁻³, μ(CuK _α) = 7.35 cm⁻¹. The structure has been refined to a finalR value of 0.050 for 6146 observed reflections. The crystals of C₃₀H₃₀O₈·CHCl₃ (GPCLF) are monoclinic, space groupC2/c,a = 28.464(4),b = 8.948(1),c = 26.480(4) Å, β = 108.93(2)°,V = 6380(2) ų,Z = 8,D _x = 1.33 g cm⁻³, μ(CuKα) = 30.42 cm⁻¹. The structure has been refined to a finalR value of 0.100 for 1980 observed reflections.

GPCLF forms an intercalate-type structure and GPBNZ a clathrate-type structure. There are, however, some similarities in the packing mode of the host molecules in these two structures. On a basis of comparison of the crystal packing of GPCLF and GPBNZ one can postulate that in the desorption process of the intercalate-type GPCLF complex an intermediate clathrate structure of the GPBNZ-type should be formed.