Solvent-dependent analysis of six 4-cyano-4'-alkylbiphenyl (5CB-10CB) in various media of different polarities using spectroscopy

Thermotropic liquid crystals (LC), 4-cyano-4′-alkylbiphenyl (nCB), have garnered attention in applications other than display such as employed in sensors, smart windows, liquid crystal lenses, PV cells, and many more, given their high optical birefringence. In this work, we examined how various solvents affect the photophysical characteristics of (5CB-10CB) LC molecules, using Fluorescence and ultraviolet-visible (UV-Vis) spectroscopies. The nCB solutions were made in various solvents of different polarities and dielectric constants. The samples showed two characteristic absorptions around 215nm and 280nm for the alkyl and aromatic rings respectively. With an excitation wavelength of 280 nm, the fluorescence spectra showed maxima around 340 nm. From the data, the solvent-induced shifts observed in the emission spectra are higher than the shifts in the absorption spectra. This may be due to differences in the excited state of the solvated molecules in varying solvents.