Fluorinated twist-bend nematogens: the role of intermolecular interaction

ABSTRACT

New ethenyl-linked dimers which differ in the fluorine-substitution pattern were prepared and characterised. The investigation has been focused on the impact of electronic structure and non-covalent interactions associated with the presence of C-F bond on the stability of the N_TB phase and overall thermal behaviour of the dimers. A joined computational and spectroscopy study showed that electrostatic interactions associated with C-F bond govern the conformational diversity of the mesogenic core without interfering with the molecular shape. The qualitative analysis of allowable inter-molecular interactions suggested that conformational diversity and flexibility of the fluorinated fragment influence the strength of intermolecular interactions and thus transitional properties, including stability of the N_TB phase. These results provide an important insight into the relationship between the electronic structure, the strength of intermolecular interactions and transitional properties, providing a valuable contribution to the design of novel functional materials.

Graphical abstract

KEYWORDS:

• Fluorinated dimers
• twist-bend nematic phase
• structure–property correlation
• non-covalent interactions

Acknowledgments

The authors thank the Croatian Science Foundation [grant ref. IP-2019-04-7978] for financial support. We are also grateful to Dr Marijana Vinković (Ruđer Bošković Institute, Zagreb) for performing the NMR measurements. The authors also acknowledge the University of Zagreb, University Computing Centre (SRCE) for granting computational time on the ISABELLA cluster.

Disclosure statement

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

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Additional information

Funding

Croatian Science Foundation, [IP-2019-04-7978].