Betulin is a lupane triterpenoid [lup-20(29)-ene3b,28-diol, C 30 H 50 O 2 ] showing high biological activity. This activity is supposed to be strongly affected by the molecular structure of its polymorphic forms. Different solvate polymorphic forms of betulin have aroused increasing interest as the possible anticancer agents of natural origin. X-ray diffraction was used to investigate crystal structure of (1:1) betulin-DMSO solvate. Title compound crystallizes in the orthorhombic P2 1 2 1 2 1 space group. Unit cell parameters are as follows: a = 7.0006(2) Å , b = 12.1623(3) Å , c = 33.6991(8) Å , Z = 4. Crystal packing and selected geometric parameters are described. It has been found that the hydrogen bonding and the dipole-dipole interaction between DMSO molecules play the major role in the formation of the crystal structure.

The theory of Debye and Bueche for the scattering of light by an amorphous solid is extended to the case where fluctuations in anisotropy as well as density are considered. A generalized correlation function is defined, which gives the probability of a simultaneous occurrence of fluctuations in polarizability in two volume elements a distance r apart. The fluctuations are specified by the magnitudes of the polarizabilities and the directions of the optic axes. The correlation function is assumed to depend on r, on the angle between the axes of the fluctuations, and on the angle giving the position of the second element with respect to the optic axis of the first. The intensities of the horizontal and vertical components of the scattered light are expressed as integrals over the correlation function of explicit functions of r and the two angles. From the initial slopes and intercepts of the intensities plotted against sin2(θ/2) where θ is the scattering angle, one can obtain average values and average dimensions of the fluctuations, and a measure of the extent to which fluctuations in density and anisotropy are correlated. The theory is applicable to glasses, gels, and liquid crystals.

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