The molecular and crystal structure of a polar mesogen 4-cyanobiphenyl-4′-hexylbiphenyl carboxylate |
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| Authors: | B R Jaishi P K Mandal Corresponding author K Goubitz H Schenk R Dabrowski K Czuprynski |
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| Institution: | 1. Physics Department , North Bengal University , Siliguri – 734430, India;2. Crystallography Laboratory , University of Amsterdam , 1018 WV Amsterdam, The Netherlands;3. Institute of Chemistry , Military University of Technology , Warsaw, Poland |
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| Abstract: | The crystal structure of the compound 4-cyanobiphenyl-4′-hexylbiphenyl carboxylate (6CBB), which exhibits both monolayer smectic A and nematic phases, has been determined by direct methods using single crystal X-ray diffraction data. The structure is triclinic with the space group P-1 and Z=2. The unit cell parameters are a=9.3511(7)?Å, b=11.2456(7)?Å, c=13.1417(6)?Å, α=85.872(4)°, β=76.258(5)° and γ=70.697(5)°. The molecule is found to be slightly bow-shaped although the alkyl chain is in all-trans conformation. The phenyl rings in 6CBB are non-coplanar. The packing of the molecules in the crystalline state is found to be a precursor to the smectic A phase structure. Comparison of crystal structures and packing of the four-ring 6CBB with those of the two-ring nCB or nOCB compounds has been made to explain the observed phase behaviour. |
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