An insight study into the parameters altering the emission of a covalent triazine framework

Covalent triazine frameworks (CTFs) synthesized through the nucleophilic substitution of 4,4′-bipyridine on the carbon atoms of cyanuric chloride were studied as fluorescent sensors. The band gap of the materials was calculated to be 2.95 eV from diffuse reflectance measurements, while from their adsorption in aqueous dispersions we obtained the value of 3.7 eV. The partial exfoliation of layered CTFs in water or tetrahydrofuran led to different morphologies, increased emission lifetimes and fluorescence quantum yields. The pattern of their light-emission properties in combination with their redox states was defined with the addition of a series of acidic and basic analytes. Another unique aspect of these semiconducting materials is their induced aggregation and subsequent enhancement of emission under ultraviolet illumination.