Exploring Cyclic Triimidazole: A Versatile Framework for Multiemissive Materials, Bioimaging and G-Quadruplex Targeting Applications

Triimidazo[1,2-a:1′,2′-c:1″,2″-e][1,3,5]triazine (TT) has recently been identified as a compact, rigid, planar, N-rich system with excellent π–π stacking ability and with moderate electron withdrawing character.1, 2 At room temperature, TT exhibits Crystallization-Induced Emissive (CIE) properties achieving a photoluminescent quantum yield of 30% due to the synergistic coexistence of fluorescence and ultralong phosphorescence with lifetimes up to 1 second. Many TT derivatives (TTs) display excitation-dependent photoluminescence, encompassing both short- and long-lived emissions of molecular and supramolecular origin and frequently revealing AIE features. Moreover, some of them show room-temperature phosphorescence (RTP) from aqueous aggregates (i.e. TT-Ph-Cz), as well as mechanochromism and vapochromism (e.g., TT-HThio, TT-(N)-Cz, TT-Ph-Cz).2-5 The present contribution will highlight the multifunctionality of these novel TTs, emphasizing their versatility in diverse applications, such as the preparation of luminescent metal complexes, explosives detection, cellular and bacterial imaging and their role as ligands for DNA G-quadruplex (G4) structures. [1] Lucenti, E.; Forni, A.; Botta, C.; Carlucci, L.; Giannini, C.; Marinotto, D.; Previtali, A.; Righetto, S.; Cariati, E., J. Phys. Chem. Lett. 2017, 8 (8), 1894-1898, https://doi.org/10.1021/acs.jpclett.7b00503. [2] Forni, A.; Malpicci, D.; Maver, D.; Lucenti, E.; Cariati, E., J. Mater. Chem. C 2025, 10.1039/D4TC04766D. [3] Malpicci, D.; Forni, A.; Botta, C.; Giannini, C.; Lucenti, E.; Marinotto, D.; Maver, D.; Carlucci, L.; Cariati, E., Dyes Pigm. 2023, 215, 111274-111283, https://doi.org/10.1016/j.dyepig.2023.111274. [4] Malpicci, D.; Forni, A.; Botta, C.; Giannini, C.; Lucenti, E.; Marinotto, D.; Maver, D.; Carlucci, L.; Cariati, E., Chemistry - A European Journal 2023, 29 (38), e202300930, https://doi.org/10.1002/chem.202300930. [5] Malpicci, D.; Forni, A.; Cariati, E.; Inoguchi, R.; Marinotto, D.; Maver, D.; Turco, F.; Lucenti, E., Molecules 2023, 28 (1), 140-153, https://doi.org/10.3390/molecules28010140.