Crystal and molecular structures of a nematogenic compound 4-(trans-4-undecylcyclohexyl) isothiocyanatobenzene (11CHBT) have been determined by direct methods using single crystal X-ray diffraction data. The compound (C₂₄H₃₇N₁S₁) crystallizes in the monoclinic system with the space group P2₁/c and Z=4. The unit cell parameters are a=5.5539(11) Å, b=8.1341(10) Å, c=51.494(5) Å, and β=91.127(14)°. The structure was refined to Rw=0.051. The molecule is found to be slightly bow-shaped though the alkyl chain is in all-trans conformation. The phenyl ring and the alkyl chain are planar and the cyclohexyl group is in chair conformation. The isothiocyanato groups are almost linear. Parallel imbricated mode of packing of the molecules is found in the crystalline state which is precursor to the nematic phase structure. There are many van der Waals’ interactions particularly in the isothiocyanato benzene part of the molecule. Of the various associated pairs of molecules the one having anti-parallel configuration with overlaps in the isothiocyanato phenyl group probably exists in both the crystalline and the nematic phases.

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