An all atom computer simulation study of the liquid crystalline phase behaviour of alkenic fluoroterphenyls

Abstract

We study the liquid crystalline phases formed by di-, tri- and tetrafluoroterphenyls using molecular dynamics simulations at the all atom level. We demonstrate the spontaneous assembly of the nematic, smectic A and smectic C phases upon cooling from the isotropic phase for difluoroterphenyls. We find that the trifluoroterphenyl system forms nematic and smectic C phases, and that the tetrafluoroterphenyl system forms only a nematic liquid crystal phase, in agreement with the experimental findings of Gasowska et al. (J. Mater. Chem., 2010, 20, 299; ref. 1). Our simulations are composed of 1500 molecules for a total of over 10⁵ atomic sites, with timescales of 10² ns. Our results show that atomistic simulations are capable of capturing macroscopic changes in the phase behaviour of a series of compounds, even when only a small variation in molecular structure is made, in this case the substitution of one or two hydrogen atoms for fluorine atoms. This leads to the intriguing possibility of theoretically designing and screening molecules for targeted liquid crystalline phases and applications.