Encapsulation of Cinnamic Acid by Cucurbit[7]uril for Enhancing Photoisomerization.

- or -configuration is required for the plant growth-promoting activity of cinnamic acid (CA), whereas the -form is inactive. Herein, we describe the encapsulation of -CA by cucurbit[7]uril (CB7) and show that photoisomerization reactions can be more efficiently controlled in aqueous solutions by utilizing this supramolecular approach. Measurements of UV-visible absorption and proton NMR spectra at different pH values confirm that -CA and its methyl ester, methyl--cinnamate (MC), form stronger 1:1 host-guest complexes with CB7 compared to cucurbit[8]uril (CB8) or three cyclodextrins (α-, β-, and γ-CD).

Solubilization of Pyridone-Based Fluorescent Tag by Complexation in Cucurbit[7]uril.

Aimed at further exploring the hosting properties of cucurbit[7]uril (CB7), we have exploited the spectroscopic and photophysical properties of a known fluorescent label as the guest molecule, namely, 3-cyano-6-(2-thienyl)-4-trifluoromethyl pyridine (TFP), in neat solvents. The formation of an inclusion host-guest complex with CB7 was checked by UV-vis absorption spectroscopy, and the value of binding constant (9.7 × 10 M) was extracted from the spectrophotometric data.

Time-resolved photoluminescence of 6-thienyl-lumazine fluorophores in cellulose acetate nanofibers for detection of mercury ions.

Time-resolved photoluminescence measurements were used to characterize the photophysical properties of 6-thienyllumazine (TLm) fluorophores in cellulose acetate nanofibers (NFs) in the presence and absence of mercuric acetate salts. In solution, excited-state proton transfer (ESPT) from TLm to water molecules was investigated at pH from 2 to 12. The insertion of thienyl group into lumazine introduces cis and trans conformers while keeping the same tautomerization structures.