Crystal structure of cholesteryl 5-(4 '-(n-decyloxy)-2 ',3 '-difluoro-biphenyl-4-yloxy)pentanoate - a liquid crystalline non-symmetric dimer

Cholesteryl 5-(4'-(n-decyloxy)-2',3'-difluorobiphenyl-4-yloxy)pentanoate was found to crystallise in the triclinic space group P1 with unit cell parameters: a=12.1282(4)angstrom, b=14.2574(4)angstrom, c=15.6294(5)angstrom, alpha = 71.584(2)degrees, beta = 79.929(2)degrees, gamma = 77.645(2)degrees, Z = 2. Three-dimensional X-ray intensity data were collected and the crystal structure solved by direct methods and refined by full-matrix least-squares procedures to a final R-value of 0.0383 for 5876 observed reflections. The asymmetric unit cell of the compound was found to contain two symmetry-independent molecules, A and B. In both the molecules, the six-membered rings of the cholesteryl moiety are conformationally very similar. However, pronounced differences are observed in the conformation of the five-membered ring, which is intermediate between half-chair and envelope in molecule A and assumes an envelope conformation in molecule B. In both the molecules, the phenyl rings are planar. The dihedral angle between the two phenyl rings is 36.3 and 38.9 degrees for molecules A and B, respectively. The molecules in the unit cell are arranged in an antiparallel manner. The crystal structure is stabilized by intermolecular C-H...O, C-H...F and C-H...pi interactions.