Cucurbit[8]uril-controlled [2 + 2] photodimerization of styrylpyridinium molecule

• Published in: Inorganic chemistry communications 2022-07, Vol.141, p.109536, Article 109536
• Main Authors: Zhao, Hui, Shen, Fang-Fang, Sun, Ji-Fu, Gao, Zhong-Zheng
• Format: Article
• Language: English
• Subjects: [2 + 2] photodimerization; Cucurbituril; Host–guest interaction; Self-assembly; Styrene group
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2022.109536

Complexation of (E)-4-(4-(1-methyl-pyridinium)styryl)-1-methyl-pyridinium chloride (SMP) guest and cucurbit[8]uril (CB[8]) host depending on the host-guest interactions which was characterized by 1H NMR spectroscopy, electronic absorption, isothermal titration calorimetry, high-resolution electrospray mass spectrum and fluorescence spectroscopy. What’s more interesting is that the styryl units in supramolecular complexes can more easily undergo [2 + 2] photodimerization under the promotion of macrocyclic CB[8] when irradiated with visible light. [Display omitted] •Complexation of SMP and CB[8] depending on the host-guest interaction.•The styryl group of SMP is located in the cavity of CB[8], resulting in a highly stable inclusion complex SMP@CB[8] with a host-guest binding ratio of 2:1.•The styryl units of supramolecular complexes can more easily undergo [2 + 2] photodimerization under the promotion of CB[8] when irradiated with visible light. he interaction of (E)-4-(4-(1-methyl-pyridinium)styryl)-1-methyl-pyridinium chloride (SMP) guest, with cucurbit[8]uril (CB[8]) host was characterized by 1H NMR spectroscopy, electronic absorption, isothermal titration calorimetry (ITC), high-resolution electrospray mass spectrum and fluorescence spectroscopy. Experimental data indicated that the styryl group of SMP resides within the cavity of CB[8] in aqueous solution, generating a highly stable inclusion complex SMP@CB[8] with a host-guest binding ratio of 1:2. Isothermal titration calorimetry experiments showed that the complexation of the SMP guest with CB[8] were enthalpy and entropy driven, which benefits from ion dipole interactions between the guest SMP and the host CB[8]. What’s more interesting is that the styryl units of supramolecular complexes can more easily undergo [2 + 2] photodimerization under the promotion of macrocyclic CB[8] when irradiated with visible light.