Solvent-dependent enthalpic versus entropic anion binding by biaryl substituted quinoline based anion receptors.

Anion receptors based on an 8-thiourea substituted quinoline with pentafluorinated (1a) or nonfluorinated (1b) biarylamide groups in the 2-position show similar binding of halide anions with somewhat higher association constants for the more acidic fluorinated derivative. Surprisingly, binding affinities for the halides in the case of the nonfluorinated 1b are similar in nonpolar chloroform or polar DMSO as solvent. Thorough thermodynamic investigations based on NMR van't Hoff analysis show that anion binding in chloroform is mainly enthalpically driven.

Naphthylthiourea-modified permethylcyclodextrin as a highly sensitive and selective "turn-on" fluorescent chemosensor for Hg2+ in water and living cells.

A naphthylthiourea-modified cyclodextrin (1) and its urea derivative (2) were synthesized, and their fluorescence behaviors in the presence of various metal ions were investigated. Significantly, 1 showed a highly sensitive and selective fluorescence sensing ability for Hg(2+) over other metal ions in both water and living cells. That is, the addition of Hg(2+) to an aqueous solution of 1 gave a significantly enhanced fluorescence at ~380 nm.

Molecular aggregation behavior of perylene-bridged bis(beta-cyclodextrin) and its electronic interactions upon selective binding with aromatic guests.

A novel water-soluble perylene bisimide derivative 1 was synthesized with two permethyl-beta-cyclodextrin grafts at the imide nitrogens, and its structure was identified by NMR, Fourier transform infrared spectroscopy (FT-IR), matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), and elemental analysis. Its aggregation behavior in water and organic solutions was further investigated by UV-vis, fluorescence, and (1)H NMR spectra, showing that 1 exhibits strong pi..