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Proceedings Paper

X-ray investigation of new isomeric oxadiazoles
Author(s): Oriano Francescangeli; L. A. Karamysheva; Sofia I. Torgova; A. Sparavigna; Alfredo Strigazzi
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Paper Abstract

An x-ray investigation has been performed on five new 2,5- disubstituted 1,2,4-oxadiazoles with reversed structures containing 4-amylbiphenyl-, trans-4-amylcyclohexylphenyl- and 2-halophenyl- as substituents. The aim was to confirm the data about the phase sequence, obtained via polarizing microscopy and differential scanning calorimetry, and to measure the structural parameters. Through x-ray diffraction technique, all substances showed only the nematic mesophase. Moreover, it was proved that some enthalphy variations previously attributed to crystal-crystal transitions are in fact due either to the rearrangement of the lattice or to the coalescence of the grains. However, for some substances, a second crystalline from c' appeared at the melting point, on cooling from the isotropic phase. C' turned out to be different from the starting form C1 of the sample, which had no thermal cycle before.

Paper Details

Date Published: 1 January 1998
PDF: 6 pages
Proc. SPIE 3319, Liquid Crystals: Chemistry and Structure, (1 January 1998); doi: 10.1117/12.301271
Show Author Affiliations
Oriano Francescangeli, Univ. degli Studi di Ancona (Italy)
L. A. Karamysheva, Organic Intermediates and Dyes Institute (Russia)
Sofia I. Torgova, Organic Intermediates and Dyes Institute (Russia)
A. Sparavigna, Politecnico di Torino and INFM (Italy)
Alfredo Strigazzi, Politecnico di Torino and INFM (Italy)


Published in SPIE Proceedings Vol. 3319:
Liquid Crystals: Chemistry and Structure
Marzena Tykarska; Roman S. Dabrowski; Jerzy Zielinski, Editor(s)

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