Intramolecularly coordinated azobenzene selenium derivatives: Effect of strength of the Se⋯N intramolecular interaction on luminescence

A series of selenium derivatives (6-12) of 2-phenylazophenyl have been synthesized using o-lithiation route. The effect of the strength of the intramolecular Se⋯N interaction on the absorption spectra as well as emission spectra has been studied. The studies suggest that the secondary bonding Se⋯N interaction give rise to fluorescence, however, the strength of Se⋯N interaction cannot be directly correlated with the intensity of the fluorescence. TD-DFT calculations show that the main transition involved in the absorption spectra of the compound is the ligand based π-π* type.