Self-assembly of T-shape 2H-benzo[d][1,2,3]-triazoles. Optical waveguide and photophysical properties

T-Shaped 2H-benzo[d][1,2,3]triazole derivatives have been synthesized by Sonogashira coupling reactions under microwave irradiation. DFT calculations were performed in order to understand the structure–property relationships – an aspect that is of vital importance for the rational design of organic self-assemblies for optoelectronic applications. Concentration-dependent 1H Pulse Field-Gradient Spin-Echo (PFGSE) NMR spectroscopy and UV/Vis spectrophotometry indicated the absence of a tendency for the aggregation of single molecules in solution. In contrast, in the solid state these compounds form organized aggregates and these were studied by scanning electron microscopy (SEM), which showed the influence that the peripheral substitution has on the morphology of the aggregates. For example, methoxy-substituted benzotriazoles self-assemble into thick and crystalline needle-like structures. However, the unsubstituted triazoles give rise to flower-like aggregates. Interestingly, the aggregates formed by benzotriazole 1c exhibit waveguide properties.