Polarity and steric effect of the lateral substituent on the mesophase behaviour of some newly prepared liquid crystals
Magdi M. Naoum
Nadia H. Metwally
Manal M. Abd eltawab
Hoda A. Ahmed
10.6084/m9.figshare.1471611.v2
https://tandf.figshare.com/articles/journal_contribution/Polarity_and_steric_effect_of_the_lateral_substituent_on_the_mesophase_behaviour_of_some_newly_prepared_liquid_crystals/1471611
<div><p>Eight homologous series of 2- (or 3-) substituted phenyl 4ʹ-(4ʺ-alkoxy phenylazo) benzoates (<b>I</b><i>n</i><sub>a–h</sub>) were prepared in which, within each homologous series, the length of the terminal alkoxy group varies between 6, 8, 10 and 12 carbons, while the other substituent, X, is a laterally attached polar group that alternatively changed from CH<sub>3</sub>, H, F, Br and CN. Compounds prepared were characterised by infrared and <sup>1</sup>H-NMR spectroscopy, and their mesophase behaviour investigated by differential scanning calorimetry and identified by polarised light microscopy. The results were discussed in terms of polarity and steric effects. The stability of the mesophase was correlated once with the dipolar anisotropy of the whole molecule and another with the dipolar anisotropy of the substituent, X. A comparative study was made between the investigated compounds and their previously prepared linear 4-substituted isomers, namely 4-substituted phenyl 4ʹ-(4ʺ-alkoxy phenylazo) benzoates (<b>I</b><i>n</i><sub>i–k</sub>).</p></div>
2015-10-10 01:46:47
terminal alkoxy group
dipolar anisotropy
series
steric
mesophase behaviour
benzoate
phenylazo
ch
cn
phenyl
substituent
polarised light microscopy