Abstract
The interaction of the conformational degrees of freedom of azomethines in the nematic phase, which is induced by electronic donor-acceptor properties of the terminal substituents of the benzylideneaniline core is studied. These degrees of freedom related to the rotation angles φ k around the bonds between the substituent and the aniline ring (φ1) and also between the CH=N bridge and the aniline ring (ω2) are characterized by the parameters Q k = 〈cos2φ k 〉. It is found that the interaction of these degrees of freedom is manifested in the linear dependence Q 2(Q 1). Within the phenomenological theory the effect of this interaction on changes δ k in the Q k values during the nematic liquid crystal-isotropic liquid phase transition is revealed along with the temperature T NI and character of this transition. The derivation of previously established empirical dependences T NI(Q k ) is presented in the presence of direct and indirect steric effects of side substituents affecting the Q k values. A diverse combination of δ k signs in the nematic phase, which is a prerequisite for the conformational polymorphism of the nematic phases of azomethines, is shown.
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Original Russian Text © 2014 E. M. Aver’yanov.
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Translated from Zhurnal Strukturnoi Khimii, Vol. 55, No. 4, pp. 641–647, July–August, 2014.
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Aver’yanov, E.M. Structural and thermodynamic consequencies of the interaction of conformational degrees of freedom of azomethines in the nematic phase. J Struct Chem 55, 605–611 (2014). https://doi.org/10.1134/S0022476614040039
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DOI: https://doi.org/10.1134/S0022476614040039