J. Physique Lett. 45, 1053-1062 (1984)
DOI: 10.1051/jphyslet:0198400450210105300

A structural investigation of the liquid crystal phases of 4-(2'-methylbutyl)phenyl 4'-n-octylbiphenyl-4-carboxylate

J. Budai, R. Pindak, S.C. Davey et J.W. Goodby

AT & T Bell Laboratories, Murray Hill, New Jersey 07974, U.S.A.

Abstract
The smectic phases of the compound 4-(2'-methylbutyl)phenyl 4'-n-octylbiphenyl-4-carboxylate (2M4P8BC) were studied by means of polarized optical microscopy, miscibility, DSC, and X-ray diffraction techniques. The phase sequence Cr ↔ G ↔ J ↔ I ↔ C ↔ A has been determined, and consequently 2M4P8BC has been shown to be the first example of a pure material exhibiting a J to G phase transition. In the optically pure form, the I* phase is a chiral hexatic phase, whereas the J* and G* phases were found to be nonchiral crystal phases. The C-centred monoclinic lattice parameters have been determined.

Résumé
On a étudié à l'aide de microscopie optique polarisée, miscibilité, DSC et diffraction de rayons X les phases smectiques du composé 2M4P8BC. On a déterminé la séquence de phases Cr ↔ G ↔ J ↔ I ↔ C ↔ A et montré que 2M4P8BC est donc le premier exemple d'un matériau pur avec une transition de phase de J à G. Dans sa forme optiquement pure, la phase I* est une phase chirale hexatique alors que les phases J* et G* sont des phases cristallines non chirales. On a aussi déterminé les paramètres de réseau de la phase monoclinique C-centrée.

PACS
6130E - Experimental determinations of smectic, nematic, cholesteric, and lyotropic structures.
6470M - Transitions in liquid crystals.
6475 - Solubility, segregation, and mixing.

Key words
lattice constants -- liquid crystal phase transformations -- optical microscopy -- organic compounds -- smectic liquid crystals -- solubility -- thermal analysis -- X ray diffraction examination of liquids -- 2M4P8BC -- J* phase -- liquid crystal phases -- 4 2' methylbutylphenyl 4' n octylbiphenyl 4 carboxylate -- smectic phases -- polarized optical microscopy -- miscibility -- DSC -- X ray diffraction techniques -- phase transition -- optically pure form -- I* phase -- chiral hexatic phase -- G* phases -- nonchiral crystal phases -- C centred monoclinic lattice parameters