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Il Nuovo Cimento D

, Volume 10, Issue 11, pp 1363–1371 | Cite as

Phase transitions and structural studies ofp-n-alkoxybenzyliden-p’-fluoro-anilines

  • C. Gandolfo
  • D. Grasso
  • G. Buemi
  • G. Torquati
Article

Summary

The transition temperatures and phase diagrams of five fluorinated benzylidenaniline derivatives have been studied by TM and X-ray diffraction techniques. A smectic polimorphism appears in all compounds. The structure of smecticB phases has been deeply studied in order to evidence a possible utilization of such phases as solvents able to exert stereochemical effects on polimerization reactions. The parameters of theS B hexagonal lattice area=b=4.29 Å in all the studied compounds, whilstc varies from 18.9Å to 24Å as a function of the C atom number of the alkyl chain; its averaged increase is 1.265Å for each CH2 group. In any case, the distance between the smectic planes is equal to the molecular length so that interdigitated structures are to be excluded.

PACS 61.30

Liquid crystals 

PACS 64.70

Phase equilibria, phase transitions and critical points of specific substances 

PACS 87.30

Biophysics of neurophysiological processes (excluding perception processes and speech) 

Riassunto

Le temperature di transizione ed i diagrammi di fase di cinque composti fluorurati della benzilidenanilina sono stati studiati mediante MT e diffrazione dei raggi X. Un polimorfismo smettico è evidente in tutti i composti. La struttura delle fasi smetticheB è stata studiata in particolare in vista di una possibile applicazione di tali fasi come solventi capaci di esercitare effetti stereochimici in fenomeni di polimerizzazione. I parametri del reticolo esagonaleS B risultano esserea=b=4.29Å per tutti i composti, mentrec varia da 18.9 Å a 24Å in funzione del numero di atomi di C della catena alchilica, con un incremento medio di 1.26Å per ogni gruppo CH2. In tutti i casi la distanza fra i piani smettici coincide con la lunghezza molecolare e quindi sono da escludere strutture interdigitate.

Резюме

Исследуются температуры переходов и фазовые диаграммы пяти флуорированных производных бензилиден-анилина с помощью TM и дифракции рентгеновских лучей. Во всех соединениях появляется смектический полиморфизм. Подробно исследована структура смектическихB фаз, чтобы использовать такие фазы, как растворитель, способный проявить стереохимические эффекты в явлениях полимеризации. Параметры гексагональной решеткиS B во всех исследованных соединениях представляютa=b=4.29 Å, тогда как величинаc изменястся от 18.9 Å до 24 Å в зависимости от числа атомов С алкильной цепочки, причём среднее увеличение составляет 1.265 Å для которой CH2 группы. Во всех случаях расстояние между смектическими плоскостями равно молекулярной длине.

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Copyright information

© Società Italiana di Fisica 1988

Authors and Affiliations

  • C. Gandolfo
    • 1
  • D. Grasso
    • 1
  • G. Buemi
    • 1
  • G. Torquati
    • 2
  1. 1.Dipartimento di Scienze Chimiche dell’UniversitàCatania
  2. 2.Sezione di Fisica del Dipartimento di Scienze dei Materiali e della Terra dell’UniversitàAncona

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