Polycatenar liquid crystals based on bent-shaped chalcone and cyanopyridine molecules

ABSTRACT

In this study, the synthesis, structural characterisation and mesomorphic and optical properties of seven new bent-shaped and polycatenar bent-shaped compounds derived from chalcone and cyanopyridine are reported. The mesomorphic behaviour was investigated by differential scanning calorimetry (DSC), polarised optical microscopy (POM) and X-ray diffraction (XRD) and correlated with the molecular structure. Two bent-core hexacatenars molecules (Ic and IIc) presented liquid crystalline properties, showing a hexagonal columnar (Col_h) phases at room temperature, being each disc constituted by two mesogens. Optical studies were also performed for the final molecules, being conducted by ultraviolet-visible and fluorescence spectrometry. The cyanopyridine derivatives show moderate luminescence quantum yields, ranging between 18% and 27%, with emission maxima around 371 nm. It is also shown that while the chalcone central unit favours a calamitic liquid crystalline behaviour in molecules with lower number of aliphatic chains, a polycatenar structure with cyanopyridine as the central unit favours a Col_h arrangement, also providing luminescence properties to the molecule.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystals
• bent-shaped
• polycatenars
• cyanopyridines
• chalcones

Acknowledgements

The authors thank the following institutions for financial support: CAPES, CNPq, PRONEX/FAPESC, INCT-Catálise. We are also grateful to the Laboratório de Difração de Raios X (LDRX-CFM/UFSC) for the XRD experiments and the Laboratório Central de Biologia Molecular Estrutural (CEBIME) for the HRMS analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the CAPES; CNPq; PRONEX/FAPESC; INCT-Catálise.