Rods to discs in the study of mesomorphism in discotic liquid crystals

ABSTRACT

The rational design of calamitic liquid crystals is an area of research that has been intensively explored due to their extensive applications in various devices. The successful methods for design have been, to some extent, mapped on discotic systems such that certain features of the structures of calamitic phases have been superimposed upon those of nematic discotic and columnar phases. In this article, we explore the correlation between nematogenic behaviour of hard rod-like particles and that of hard disc-like systems. We show that for calamitics, nematic behaviour is observed, whereas for discotics this is not the case. Furthermore, we show that nematic discotic materials are miscible, whereas unlike smectics, columnar phases are less likely to be miscible. Indeed, it appears that columnar discotic phases are greater similarities with soft-solids than true liquid crystals.

Graphical Abstract

KEYWORDS:

• Discotics
• amphiphiles
• phase diagrams
• eutectics

Acknowledgement

Many years ago when I was tasked to synthesise smectic C liquid crystals, there was little idea what molecular constraints there were in material design. After struggling through many successful and unsuccessful preparations, I finally got out protractors and compasses and started modelling on a piece of graph paper. Fifteen years later, we had progressed to computer simulations. The gap between molecular and macro-molecular modelling was still immense, and our funders were posing me questions such as, “Can’t you model materials with suitable physical properties for applications without making them?” Today, we have a plethora of modelling possibilities to utilise, such as coarse grain modelling, Gay-Bern simulations and density functional theory. The gap has closed, and this has been due to Claudio’s underpinning research into the modelling of all brands of liquid crystals.

Thus, with our immense appreciation to Claudio for the many conversations we have had with him and the cross-disciplinary support that he has given to us as experimentalists; we dedicate our article to him. And from everyone here at York University, we wish him a very happy retirement.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1.. Variations in the modelling and simulations of chemical structures were performed using either ChemDraw 3D or Gaussian 09, Revision E.01M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, G. A. Petersson, H. Nakatsuji, X. Li, M. Caricato, A. Marenich, J. Bloino, B. G. Janesko, R. Gomperts, B. Mennucci, H. P. Hratchian, J. V. Ortiz, A. F. Izmaylov, J. L. Sonnenberg, D. Williams-Young, F. Ding, F. Lipparini, F. Egidi, J. Goings, B. Peng, A. Petrone, T. Henderson, D. Ranasinghe, V. G. Zakrzewski, J. Gao, N. Rega, G. Zheng, W. Liang, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, K. Throssell, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, J. M. Millam, M. Klene, C. Adamo, R. Cammi, J. W. Ochterski, R. L. Martin, K. Morokuma, O. Farkas, J. B. Foresman, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2016.

Additional information

Funding

This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/L012375/1], [grant number EP/J007714/1] and [grant number EP/E064299/1]; the Leverhulme Trust, the European Science Foundation; Kingston Chemicals; DERA/QinetiQ; and the Wild Trust of the University of York.