Strongly luminescent and liquid-crystalline π-conjugated 2-methyl[1,2,3]benzotriazoles with a linear donor-acceptor-donor structure

• Published in: Journal of molecular liquids Vol. 314; p. 113616
• Main Authors: da Silva, Elias Regis, Hinojosa, Abad Roger Castillo, Eccher, Juliana, Tonet, Michele Duarte, Brondani, Daniela, Zapp, Eduardo, Curcio, Sergio Fernando, Postacchini, Bruna Bueno, Cazati, Thiago, Vieira, André Alexandre
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-09-2020
• Subjects: 1,2,3-Benzotriazole; Charge transfer; Liquid crystals; Luminescence; 1,2,3-Benzotriazole; Charge transfer; Liquid crystals; Luminescence
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2020.113616

Symmetrical 2-methyl[1,2,3]benzotriazole (BZT) derivatives with elongated peripheral units connected via acetylenic triple bonds present calamitic thermotropic mesomorphism with nematic and smectic phases. They show intense photoluminescence with near-unity quantum yields in solution. The peripheral groups significantly influence the excited-state lifetime. Fluorescence quenching is observed in the presence of C60, testifying of charge transfer to the fullerene acceptor. The varying sterical demand of the different substituents considerably influences the efficiency of the charge transfer induced fluorescence quenching. HOMO, LUMO and band gap energies ranged from −5.15 to −5.97 eV (ionization potential), −2.47 to −2.96 eV (electron affinity) and 2.68 to 3.08 eV (optical band gap).
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•A novel luminescent liquid crystals based on the 2-methyl[1,2,3]benzotriazole•The molecules presented calamitic mesomorphism.•Compounds exhibited strong photoluminescence in solution and solid film.•Doping with C60 suggested charge transfer, being dependent on the π-conjugate core.