Supramolecular Recognition of Amino Acids by Twisted Cucurbit[14]uril.

Binding interactions between twisted cucurbit[14]uril (tQ[14]) and twenty standard amino acids (AAs) have been investigated by NMR spectroscopy and isothermal titration calorimetry (ITC) in aqueous HCl solutions and in DMSO. The results showed that tQ[14] displays clear binding affinity for AAs with a positively charged side chain or containing an aromatic ring, but weaker binding affinity for AAs with hydrophobic or polar side chains, with the binding mode depending on the type of side chain present in the AAs.

[The Interaction of Cucurbit[8]uril with Thionine and Carbendazim with Spectroscopic Method].

In this paper, the interaction of cucurbit [8]uril(Q[8]) with thionine (TH) and carbendazim (CBZ) were investigated with fluorescence and UV-Vis spectroscopy. The experimental results showed that the inclusion complex between Q[8] and TH informed was at molar ratios of 1∶2 in 0.01 mol·L-1 hydrochloric acid solution. The fluorescence intensity of the Q[8]/TH complexes quenched when Q[8] was added to TH solution, but fluorescence increasing of the Q[8]/TH complex with the addition of CBZ was observed. The fluorescence increasing values show a good linear relationship with the CBZ concentration within 0~3.5 µmol·L-1. The linear regression equation relating fluorescence intensity (If) to CBZ concentration (c) is If=0.45c+32.24 (r=0.999). The detection limit was 9.39×10-8 mol·L-1. Forthemore, the influence of foreign species on the analytical signal of the Q[8]/TH complex in the presence of carbendazim was established. No interference was observed from commonly used foreign species such as metal ions (Fe3+, Mg2+, Ca2+). In particular, benzimidazole compounds thiabendazole and fuberidazole do not interfere with CBZ determination at a specific concentration. The results revealed that complexation of Q[8] and TH with CBZ offers a fluorescent switching "on-off" effect which will supply a potential application in pesticide residues test.

A novel shell-like supramolecular assembly of 4,4'-bipyridyl derivatives and a twisted cucurbit[14]uril molecule.

This work showed that the 4,4'-bipyridyl group and alkyl chains of 4,4'-bipyridyl derivatives are completely located in the shell-like cavity of the twisted cucurbit[14]uril molecule and formed novel shell-like 1 : 1 inclusion complexes. As it is enthalpy-driven the complexation benefits from ion-dipole interactions.