Benzotriazole-based multidonor-acceptor systems as attractive two-photon absorption dye platforms

Pyrazine-decorated benzotriazole cores allow the orthogonal combination of two dipolar systems within a single molecule. A series of this type of derivatives was synthesized and their photophysical features were studied. The properties of these compounds showed remarkable differences in function depending on the substitution in the pyrazine ring of the benzotriazole core. Furthermore, the two-photon absorption property (2PA) was studied to determine the structure-properties relationship for the reported compounds. The best dye achieved a crosssection of 1532 GM, which was higher than values previously obtained for similar D-pi-A-pi-D benzotriazole derivatives. TD-DFT calculations, which supported the experimental observations, indicating the interaction between the two dipolar systems was responsible for enhancing the 2 PA properties and favoring bathochromic shifts.