Color-tunable photoluminescent discotic liquid crystal based on perylene – Pentaalkynylbenzene triad

This article describes the design and development of a discotic triad, where perylene is sandwiched between two pentaalkynyl benzene units, linked via a flexible alkyl spacer. The thermotropic liquid crystalline properties of the compound were analyzed by differential scanning calorimetry (DSC), polarising optical microscopy (POM), and wide-angle X-ray diffraction (WXRD) techniques. The compound exhibits columnar oblique (Colob) mesophase that sustains over a significant temperature range. The corresponding electron density map was derived from the intensities observed in the diffraction pattern. The photophysical behaviour of the compound in various solvents of varying polarity has been studied. The compound shows positive solvatochromism with a significant increase in Stoke's shift of around 91 nm between toluene and ethanol. The compound shows high fluorescence quantum yield in non-polar solvents and the lowest in polar solvents. The presented luminescent material with positive solvatochromism will reveal its potential application in fluorescence imaging and the field of optoelectronic organic materials.