Mesomorphic behaviour and photoluminescence study of novel homologous series of Schiff’s base derived from cholesteryl carbonate and thiadiazole moiety

ABSTRACT

The steroidal derivatives are widely known for their ability to display a variety of mesophases, including frustrated phases, depending on the structure of the steroidal skeleton and the substituents attached. In this report, thirteen new homologues Schiff’s base derivatives were synthesised by condensing 4-formyl phenyl cholesteryl carbonate with 5-(4’-n-alkoxy phenyl)-2-amino-1,3,4-thiadiazole. All the synthesised derivatives were characterised using elemental analysis, FT-IR, ¹H-NMR and ¹³C-NMR. Optical texture studies were carried out using a polarising optical microscope in heating and cooling cycles to examine the liquid crystalline behaviour of the synthesised compounds. The derivatives displayed a variety of mesophases, including chiral nematic (N*), twist grain boundary-A (TGB_A), smectic A (SmA) and chiral smectic C (SmC*) phases. The isotropic temperature of all the compounds within the homologous series seems to decline with the increase in carbon numbers on flexible chains. The thermal behaviour of all the synthesised compounds was checked using differential scanning calorimetry and thermogravimetric analysis. All the synthesised compounds are UV-active and exhibit photoluminescence in the blue emission band with a remarkable quantum yield. The radical-scavenging activity of the synthesised mesogenic derivatives was also evaluated using the DPPH assay.

GRAPHICAL ABSTRACT

KEYWORDS:

• Thiadiazole
• Schiff’s base
• cholesteryl carbonate
• twist grain boundary
• photoluminescence

Acknowledgments

The authors are thankful to the Head, Applied Chemistry Department, Faculty of Technology and Engineering, The Maharaja Sayajirao University of Baroda, Vadodara, India, for providing the facility to carry out the research work. The authors are also grateful to the Gujarat government for SHODH (Scheme of Developing High-Quality Research) fellowship.

Disclosure statement

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

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02678292.2024.2319631.