Bowl-shaped fluorescent liquid crystals derived from 4-tert butyl calix[4]arene and trans cinnamic acid derivatives

Abstract

A new family of bowl-shaped molecules with a calix[4]arene rigid core appended by four-side and two-side substitution with trans 4-n-alkoxy cinnamic acid has been synthesized and well characterized. The LC behaviours of the novel materials were studied by using optical polarising microscopy, differential scanning calorimetry and high-temperature powder X-ray diffraction methods to confirm the smectic organization. It is found that all of the prepared materials display enantiotropic LC phases in the present series-1 (1d₄-1, 1d₅-l, 1d₈-1, 1d₁₀-l, 1d₁₂-l, 1d₁₄-l) and series-2 (1d₄-1l, 1d₅-ll, 1d₈-1l, 1d₁₀-ll, 1d₁₂-ll, 1d₁₄-ll). The electrochemical behaviour shows the higher reactivity of the proposed derivatives, which is in good agreement with the DFT values. The relationship between the structure and the mesomorphic behaviour of the compounds in both series is discussed. These synthesized supramolecular compounds show blue luminescence in solution as well as in solid thin films under long wavelength UV light. To get more insights, HOMO and LUMO studies were carried out, which support intramolecular charge transfer interactions in this class of mesogens.