The synthesis, two-photon absorption and blue upconversion fluorescence of novel, nitrogen-containing heterocyclic chromophores

Novel, nitrogen-containing heterocyclic chromophores based on either 1,2,4-triazine or an imidazole core were synthesized using a three-component, one-pot reaction under microwave irradiation. Structures were verified by H-1 NMR, IR, MS and elemental analyses while crystal structure was determined using X-ray diffraction. The two-photon absorption and two-photon upconverted blue fluorescent emission characteristics were investigated experimentally: preliminary structure-photophysical property relationships were established. Chromophores that contained the imidazole moiety displayed more potent two-photon absorption than compounds based upon 1,2,4-triazine and also exhibited a strong two-photon upconverted blue fluorescent emission peak at around 443-476 nm. Significant enhancement of the two-photon absorption cross-section was achieved by fusing a benzoxazole moiety onto the phenanthro[9,10-d]imidazole ring. (C) 2008 Elsevier Ltd. All rights reserved.