Accession Number:

ADA199642

Title:

X-Ray Diffraction Studies of Homologous Series of 4-Alkyl-4' Cyanostilbene

Descriptive Note:

Interim rept.

Corporate Author:

CONNECTICUT UNIV STORRS

Report Date:

1988-09-23

Pagination or Media Count:

11.0

Abstract:

Various members of the series 4-alkyl-4-cyanostilbene n4,...11 have been examined by x ray diffraction using monodomain samples aligned in .2 T magnetic field. A moving film technique has been employed with Fe K radiation 1.937 A to record the zero level and upper levels in reciprocal space. Lower members n4,5,6 form only a nematic phase higher members n10,11 form only a smectic-A phase while intermediate members n7,8,9 form both nematic and smectic-A phases. The equatorial reflections were used to establish effective side-chain separations while meridional reflections permitted the calculation of effective molecular lengths and layer thickness, respectively, in the nematic and smectic phases. These were found to be longer than the calculated molecular length in its most extended conformation. For the smectic-A phases, this implies some type of bilayer structure like that reported for other liquid-crystal compounds having polar end groups. Keywords Moving film technique, X ray diffraction, Smectic, Partial bilayer, Nematic.

Subject Categories:

  • Organic Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE