Using time-dependent density functional theory to simulate UV-visible absorption spectra and calculate corrected emission energies of 2,1,3-benzotelluradiazoles

Luminescent benzochalcogenadiazole liquid crystals have attracted considerable interest owing to their combination of photophysical and mesomorphic properties. These compounds consist of central heterocycles containing oxygen, sulfur or selenium, linked to phenyl groups via triple bonds. These groups are then connected to uniform-length alkyl chains. The delocalized electrons in the conjugated systems are responsible for the photophysical properties, while the chain length and functional groups determine the mesomorphic behaviour of these compounds. Using time-dependent density functional theory and polarizable continuum modelling, we simulated the ultraviolet–visible absorption spectra of 2,1,3-benzochalcogenadiazole derivatives with tellurium in the central heterocycle to elucidate their photophysical properties. The emission process was evaluated using the state-specific corrected linear response approach. Non-relativistic and Douglas–Kroll–Hess calculations employed the CAM-B3LYP functional with all-electron basis sets. We estimated the impact of various solvents and alkyl chain lengths on absorption and emission energies and oscillator strengths. These compounds have not been reported in the literature before.