The title compound, 4-n-nonylbenzoic acid, CH 3 (CH 2 ) 8 C 6 H 4 COOH (NBA), has been characterized thus: triclinic, P1, a = 13.514( 4) A Ã , b = 23.4672 (5) A Ã , c = 7.658 (3) A Ã , a = 90.914( 3)ß , b = 100.403( 3)ß , c = 77.781( 2)ß , V = 2334 (2) A Ã 3, Z = 2, and F.W = 745.06, D m = 1.161 g cmÕ 3, D c = 1.061 g cmÕ 3, F 000 = 816.00, l = 0.71069 A Ã , m = 0.6 cmÕ 1, goodness-of-t is 1.029, nal R1 = 0.063 and wR2 = 0.16. Introductionbe indexed with respect to a triclinic cell. Lorentz and The crystal structure studies of mesogens provide polarization corrections were applied. The structure was insight into the understanding of physical properties and solved using SHELXS-97 [3]. The structure solution phase transitions. In view of this a crystal structure did not yield any meaningful E-map in the space group study of 4-n-nonylbenzoic acid was undertaken. The P1 Å , even though the E-statistics showed better agreecompound melts into the nematic state at 97.7ß C and ments of zonal and all data with the centrosymmetric into the isotropic phase at 114.8ß C. The material exhibits system. A structure solution in P1 Å did not give a good a very small positive dielectric anisotropy and it has a combined gure of merit. The resulting E-map did not very small dipole moment [1], as compared with other reveal the complete structure nor could it be further mesogens. The dielectric constant along the preferred expanded by a diOE erence Fourier map after a few cycles direction (along the nematic director) is slightly greater of re nement. than that in the transverse direction. The small value of Subsequently the structure was solved in the nonthe dielectric constant is due to the absence of a strongly centric space group P1. The peak list from SHELXS-97 polar end group. The dipole moment contributed by the revealed all the phenyl rings and the side chains were COOH group is 1.7 D whereas the dielectric anisotropy revealed partially. The diOE erence Fourier map showed is in the range 0.15-0.38 D. The dipole moment of the the positions of all missing non-hydrogen atoms. The molecule is 0.40 D. 4-n-Nonyl benzoic acid in pure form structure was re ned by full matrix least-squares using is not used for electro-optic devices because of low SHELXL-97 [4], using 6002 unique re ections. The birefringence, but there is a continued interest in nematic hydrogen atoms were generated at chemically acceptable liquid crystals with low optical birefringence, as is evident positions and re ned with isotropic thermal parameters from the work of Dalmolen et al. [2]. assigned to them. 997 parameters were re ned using 5352 observed re ections with I > 2s(I) to R1 = 0.063 and wR2 = 0.16. In the nal diOE erence map Dr max = 0.191, ExperimentalDr min = Õ 0.203 e A Ã Õ 3, and goodness-of-t = 1.029. After Clear needle-shaped crystals of the title compound the completion of the structure, the coordinates were (Merck Ltd., England ) were obtained from a solution in checked for missing symmetry using BUNYIP [5 ]. No acetone. A crystal of approximate siz...

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Key indicators: single-crystal X-ray study; T = 296 K; mean (C-C) = 0.003 Å; R factor = 0.039; wR factor = 0.105; data-to-parameter ratio = 12.5.In the title compound, C 17 H 13 ClN 2 O 2 , the phenyl and chlorobenzene rings are inclined to the central pyrazole ring at 40.84 (9) and 65.30 (9) , respectively. In the crystal, pairs of C-HÁ Á Á interactions link the molecules into inversion dimers and C-HÁ Á ÁO hydrogen bonds link these dimers into columns extended in [010]. The crystal packing exhibits short intermolecular OÁ Á ÁCl contacts of 3.0913 (16) Å . Related literature

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