Photochromic characteristics, photomodulated luminescence and ammonia vapor sensing properties of three D-A supramolecular assemblies

• Published in: Journal of molecular structure 2022-06, Vol.1257, p.132609, Article 132609
• Main Authors: Zhu, Baili, Jin, Yunpeng, Chu, Jingying, Jiang, Jian, Zuo, Minghui, Cui, Shuxin
• Format: Article
• Language: English
• Subjects: Ammonia vapor sensing; D-A system; Electron-transfer; Photochromism; Photomodulated luminescence; Viologen
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2022.132609

•Three donor-acceptor compounds were designed and synthesized, and their structures were studied.•Compounds 1–3 exhibit photochromic properties and interesting photomodulated luminescence properties.•Compound 1 can be used as an ammonia vapor sensor. Synthesized three different supramolecular polymers, {[(4-BCBPY)0.5(H2BTEC)0.5]·H2O}n (1), {[(4-BCBPY)(C2H5NO)Cl]·H2O}n (2) and {[(4-BCBPY)(C2H5NO)Cl]·H2O}n (3) (H2BTEC2− = 1,2,4,5-benzenetetracarboxylic acid anion). In compound 1, benzene carboxylic acid anion acts as an electron donor, and electron-deficient viologen acts as an electron acceptor to form a supramolecular assembly. In compounds 2 and 3, electron-deficient viologen forms supramolecular assemblies with N-methylformamide, water and chloride ions. All three compounds are connected through non-covalent interactions and form a donor-acceptor (D-A) system. Compounds 1, 2 and 3 all exhibited photochromic behavior of electron transfer, while also exhibiting interesting photomodulated luminescence behavior. And compound 1 can also be used as an ammonia vapor sensor material. The photochromic mechanism of the compound and the correlation between calculation and practice are deeply studied by using time-dependent density functional theory (TDDFT). [Display omitted] Three new supramolecular compounds {[(4-BCBPY)0.5(H2BTEC)0.5]·H2O}n (1), {[(4-BCBPY)(C2H5NO)Cl]·H2O}n (2) and {[(4-BCBPY)(C2H5NO)Cl]·H2O}n (3) were synthesized using viologen ligands 4-BCBPY·2Cl (1,1′-bis(4-cyanobenzyl)-4,4′-bipyridinium dication) and H4BTEC as raw materials. The effects of metal salts and pH on the structures of the three compounds were studied. Under the irradiation of 350 W xenon lamp, the three compounds change from their original color to blue, which is caused by photo-generated viologen free radicals. Compounds 1, 2 and 3 also showed interesting photomodulated luminescence behavior. At the same time, compound 1 can be used as an ammonia vapor sensor.