Amino-[1,1′]-biphenyl-containing 3-aryl-[1,2,4]triazolo[4,3-c]quinazoline derivatives with fluorescent properties have been designed and synthesized. The type of annelation of the triazole ring to the pyrimidine one has been unambiguously confirmed by means of an X-ray diffraction (XRD) method; the molecules are non-planar, and the aryl substituents form the pincer-like conformation. The UV/Vis and photoluminescent properties of target compounds were investigated in two solvents of different polarities and in a solid state. The samples emit a broad range of wavelengths and display fluorescent quantum yields of up to 94% in toluene solutions. 5-(4’-Diphenylamino-[1,1′]-biphenyl-4-yl)-3-(4-(trifluoromethyl)phenyl)-[1,2,4]triazolo[4,3-c]quinazoline exhibits the strongest emission in toluene and a solid state. Additionally, the solvatochromic properties were studied for the substituted [1,2,4]triazolo[4,3-c]quinazolines. Moreover, the changes in absorption and emission spectra have been demonstrated upon the addition of water to MeCN solutions, which confirms aggregate formation, and some samples were found to exhibit aggregation-induced emission enhancement. Further, the ability of triazoloquinazolines to detect trifluoroacetic acid has been analyzed; the presence of TFA induces changes in both absorption and emission spectra, and acidochromic behavvior was observed for some triazoloquinazoline compounds. Finally, electronic-structure calculations with the use of quantum-chemistry methods were performed for synthesized compounds.

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A series of novel V‐shaped luminophores containing electron‐withdrawing dibenzo[f,h]quinoxaline core and arylthienyl donor fragments at positions 2 and 3 has been synthesized. The absorption spectra (UV/vis) were recorded in several solvents, whereas emission spectra were recorded in solutions and powders. The solvatochromism as well as halochromism of obtained compounds was also explored. Electronic‐structure calculations using quantum‐chemistry methods were performed to further analyse experimental results. All characteristics were compared with that of 2,3‐bis(arylthienyl)quinoxaline counterparts. The halochromic effect studies showed that upon gradual addition of trifluoroacetic acid (TFA) to the toluene solution of diethylaminophenyl‐substituted dibenzo[f,h]quinoxaline chromophore, absorption and emission changed. Observed band shifts were more distinct in the case of mentioned quinoxaline than for other derivatives. All of the (dibenzo[f,h])quinoxaline chromophores exhibited good sensitivity toward nitro‐containing explosives with high Stern‐Volmer constants up to 57800 M−1, these results are remarkable for such heterocyclic systems.