Title:	Dipolar origin of tilting of rod-like molecules in the smectic C phase
Authors:	Madhusudana, N.V.
Keywords:	molecular tilting in layers molecular theories off-axis dipoles odd-even effects re-entrant smectic A phase Invited article
Issue Date:	Aug-2015
Publisher:	Taylor & Francis
Citation:	Liquid Crystals, 2015, Vol. 42, p 840-863 (Invited Article)
Abstract:	We review various proposed molecular mechanisms for tilting of rod-like molecules in the smectic C phase. We analyse some experimental results, viz. (1) unusual odd–even effects in smectic A to nematic (TAN) and smectic A to smectic C (TAC) transition temperatures and/or maxima in TAC in some homologous series of compounds, (2) occurrence of re-entrant SmA and/or hexatic SmB as lower temperature phases, (3) SmC replaced by SmA when a halogen atom is substituted at the end of one of the chains, (4) suppression of SmC phase at high pressures, and in binary mixtures with dissimilar aromatic cores or chain lengths, (5) induction of SmC phase in mixtures of some structural isomers and (6) some recent all-atom simulations. The results can be understood on the basis of our molecular theory in which the tilting occurs due to the repulsive coulomb interaction between neighbouring molecules having off-axis dipoles with transverse components and freely rotating about their long axes in smectic layers. The model also takes into account the entropic cost of tilting which depends on the length to width ratio of the molecules. We have included some simple calculations of the induced dipoles in the chains to account for the odd–even effects.
Description:	Restricted Access.
URI:	http://hdl.handle.net/2289/6367
ISSN:	0267-8292 1366-5855 (Online)
Alternative Location:	http://dx.doi.org/10.1080/02678292.2014.987707
Copyright:	2015 Taylor & Francis
Appears in Collections:	Research Papers (SCM)

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