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Cong H.,Guizhou University | Wang Q.,Guizhou University | Zhang J.,Guizhou University | Zhang J.,Key Laboratory of Chemistry for Natural Products of Guizhou Province | And 2 more authors.
Chinese Journal of Organic Chemistry | Year: 2012

Three kinds of 1, ω-bi(2-aminopyridinium)alkylates, which are the 1,4-bi(2-aminopyridinium)butane dibromide (C4), l,6-bi(2-aminopyridinium)hexane dibromide (C6) and l,8-bi(2-aminopyridinium)octane dibromide (C8), have been synthesized, respectively. The host-guest interactions of cucurbit[8]uril (Q[8]) with the above compounds have been investigated using 1H NMR and UV-vis spectra, and the results showed that there were different interaction models in the three host-guest systems. Subsequently, the photocycloaddition reactions of the substrates have been carried out in the presence of Q[8], and the dependence of the supramolecular catalytic active on the construction of substrate was observed.

Song G.-X.,Guizhou University | Tang Q.,Guizhou University | Huang Y.,Guizhou University | Zhang J.-X.,Key Laboratory of Chemistry for Natural Products of Guizhou Province | And 4 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2015

The interaction between Q[8] with β-indoleacetic acid and the methylviologen was studied in aqueous solution with electronic absorption spectroscopy (UV-Vis), fluorescence spectroscopy, 1H NMR spectroscopy and isothermal titration calorimetry (ITC) in details. The authors explored the mode of action, action site and thermodynamic properties of the host-guest system. The electronic absorption and fluorescence spectroscopy data showed that the Q[8]/IAA system and Q[8]/MV2+ system informed 1∶1 inclusion complexes in aqueous solution. ITC results showed that the changes of Gibbs free energy and enthalpy are all negative, it suggested that complex formation was spontaneous and exothermic reaction. Moreover, ITC results for the Q[8] and IAA with MV2+ indicate that the association constants of the Q[8]-IAA and Q[8]-MV2+ complexes were (3.22±0.96)×105 L·mol-1 and (3.90±0.91)×106 L·mol-1, respectively. Therefore, the interaction between Q[8] and IAA with the MV2+ was a competitive process. This likely occurs because the MV2+ and IAA molecules attempt to occupy the Q[8] cavity, which reduces the fluorescence and absorption spectra intensity of Q[8]-IAA because of the formation of a new inclusion complex between Q[8] and IAA with MV2+. In addition, with the addition of MV2+ to a Q[8]/IAA complex, 1H NMR results showed that the indole moieties of β-indoleacetic acid and bipyridyl group of methylviologen can be incorporated into Q[8] cavities because of electronic transfer MV2+ with PQ in a Q[8] cavity with ternary complexes. These results provides the potential applications for the supramolecular self-assembly in cucurbit[n]urils field. © 2015, Science Press. All right reserved.

Xiao X.,Guizhou University | Tu S.-C.,Guizhou University | Xue S.-F.,Guizhou University | Zhu Q.-J.,Guizhou University | And 3 more authors.
Gaodeng Xuexiao Huaxue Xuebao/Chemical Journal of Chinese Universities | Year: 2013

One guest 1-butyl-4,4'-bipyridinium bromide (BV+) was designed and synthesized, while supramolecular assemblie of tetramethylcucurbit [6] uril (TMeQ[6]) with the guest BV+ was investigated by 1H NMR and UV-Vis absorption spectra, thermogravimetry analysis and X-ray crystallography in details. The experimental results showed that TMeQ[6] can preferred encapsulate the butyl moiety of the 1-butyl-4,4'-bi-pyridinium guest in its hydrophobic cavity to form inclusion complexes with a ratio of 1:1 in the aqueous solution and solid state. This observation contributes to a deeper understanding in molecular recognition, design and construction of novel molecular machines.

Cheng X.-J.,Guizhou University | Liang L.-L.,Guizhou University | Chen K.,Guizhou University | Ji N.-N.,Guizhou University | And 7 more authors.
Angewandte Chemie - International Edition | Year: 2013

All in a twist: The largest cucurbit[n]uril, namely tQ[14] (see picture; colors indicate sides of the molecule) contains 14 normal glycoluril units linked by 28 methylene bridges. However, it contains a 360° twist. As a consequence, it does not have a normal cavity like the most cucurbit[n]urils, and instead has a folded, figure-of-eight conformation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Song G.-X.,Guizhou University | Tang Q.,Guizhou University | Huang Y.,Guizhou University | Wang R.,University of Macau | And 5 more authors.
RSC Advances | Year: 2015

The supramolecular interactions among thioflavin T (ThT), two herbicides paraquat (PQ) and diquat (DQ), and macrocyclic cucurbit[8]uril (Q[8]), were studied using spectrofluorimetry, ultraviolet-visible absorbance spectrometry, 1H nuclear magnetic resonance spectroscopy, and isothermal titration calorimetry. A new method based on fluorescence quenching of the fluorescent host-guest complexes of Q[8]-ThT (the probe) upon cooperative binding with PQ or DQ to form a ternary complex, was proposed for the analytical determination of the two herbicides in aqueous solutions. Detection limits of 7.95 × 10-9 mol L-1 and 8.07 × 10-9 mol L-1 were obtained for PQ and DQ, respectively. Recoveries obtained by the proposed method in real-world examples such as river water and cabbage extracts were 104-108%. Interestingly, this method demonstrated high selectivity towards PQ and DQ in the presence of various metal ions and quaternary ammonium substances. Such a method provides a rapid, selective, sensitive and facile strategy for herbicides detection and quantification. © 2015 The Royal Society of Chemistry.

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