Influence of multifluorophenyloxy terminus on the mesomorphism of the alkoxy and alkyl cyanobiphenyl compounds in search of new ambient nematic liquid crystals and mixtures

ABSTRACT

A series of cyanobiphenyl (CB) and cyano-p-terphenyl (CT) derivatives containing a variety of highly fluorinated aryloxyl termini and different connecting bridges were efficiently synthesized via aromatic nucleophilic substitution (S_NAr) and their mesogenic properties described. Comparison with the non-fluorinated analogues indicates that the terminal multifluoroaryloxy group generally decreases the crystal to nematic phase transistion temperature and enhances the supercooling of these mesogens. Furthermore, several binary LC mixtures formed by the multifluoroaryloxy tail-terminated compounds were found exhibiting promising wide room temperature nematic phases ranges comparable to the commercial quaternary mixture E7. Our binding free energy (G_BE) calculations predict that the fluorinated aryloxy terminated molecules tend to assume homeotropic orientation on Al(ClO₄)₃ and Ni(ClO₄)₂ metal salt decorated surfaces, which is consistent with the observed anchoring behavior. As such, these materials are promising candidates for chemoresponsive sensor devices which display a rapid response to a variety of analytes.

Graphical Abstract

KEYWORDS:

• cyanobiphenyl
• aromatic nucleophilic substitution
• nematic phase
• homeotropic anchoring
• chemoresponsive sensor

Acknowledgments

This work was supported by the National Science Foundation (DMREF grant: DMR-1921668, DMR-1921696, and DMR-1921722). Part of the computational work conducted by T.S., J.G. and M.M. in this study was carried out at various external computational resource facilities through the DoD High Performance Computing Modernization Program (US Air Force Research Laboratory DoD Supercomputing Resource Center (AFRL DSRC), the US Army Engineer Research and Development Center (ERDC), and the Navy DoD Supercomputing Resource Center (Navy DSRC), grant number: ARONC43623362), all supported by the Department of Defense.

Disclosure statement

No potential conflict of interest was reported by the author(s).

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Funding

This work was supported by National Science Foundation [1921668, 1921696 and 1921722].