Sugar-based carboxamidoquinoline conjugate for sensing Cu2+ and Au3+ ions in water through different binding modes and real application.

A simple water-soluble carboxamidoquinoline derivative of glucofuranose 1 exhibited reversible selectivity toward Cu2+ and Au3+ ions in different binding modes. Sensor 1 is an example of a dual sensor for identifying copper and gold ions in the water medium. Sensor 1 exhibited excellent selection ability and sensitivity for Cu2+ and Au3+ ions rather than several metal ions and anions with a wide pH range (5-10). The association constants for both ions were determined to be 3.58 × 104 M-1 and 1.84 × 104 M-1, respectively. The 1:1 binding chemistry of the complexes was verified from the Job method and again validated through mass spectra. Sensor 1 can detect Cu2+ and Au3+ ions at very low concentrations, such as 0.014 µM for Cu2+ and 0.058 µM for Au3+. The different sensing strategies of sensor 1 towards Cu2+ and Au3+ were manifested from the photophysical properties of sensor 2 with metal ions, FT-IR spectra, and theoretical (DFT) observations. The useful relevance of the sensor for Cu2+ and Au3+ ions was tested in different water samples.

Solvent Controlled Colorimetric and Fluorometric Detection of Fe2+ and Cu2+ Ions by Naphthaldimine-Glucofuranose Conjugate.

The sensing properties of naphthaldimine-glucofuranose conjugates 1 and 2 towards metal ions were investigated by 1H NMR titration, Fourier-transform infrared spectroscopy (FTIR), absorbance, and fluorescence spectroscopic methods. The absorbance and fluorescence studies indicated that compound 1 formed coordination with Fe2+ and Cu2+ ions in dimethyl sulfoxide (DMSO) through color changes yellow to brown and colorless, respectively. The Job's plots using absorbance data showed metal-ligand binding ratio is 1:1 for both cases. The formation of 1-Fe2+ and 1-Cu2+ complexes have been analyzed by absorption and emission spectroscopy, high-resolution mass spectrometry (HRMS) data, FTIR, 1H NMR titration experiment, and density functional theory (DFT) calculations. The detection limits of naphthaldimine sugar conjugate 1 towards Fe2+/Cu2+ were calculated from UV-vis and fluorescence data according to the standard method. The sugar-naphthaldimine conjugate 2 has been used to establish the binding mode of 1 with Fe2+ or Cu2+ ions in DMSO.

Conformationally Locked Tolans, ß-Sheet Structures, and Photophysical Properties.

Conformationally locked tetrasubstituted tolans were synthesized by introducing a tether on the tolan. To demonstrate the utilities of these motifs, a ß-hairpin structure (15) was synthesized, and its additional stabilizing effects were evaluated. Moreover, the photophysical properties of cyclic tolans and their ß-sheet structure were investigated. The fluorescence quantum yield of cyclic tolan 12 is >1000 times stronger than its congener 1 in CH3CN.

Hg(II)-mediated intramolecular cyclization reaction in aqueous media and its application as Hg(II) selective indicator.

The Hg(II)-specific intramolecular cyclization reaction of ethynyl phenols was carried out for the first time in semiaqueous media at ambient temperature. The reaction unit (ethynyl phenol) was coupled with a malononitrile derivative (signal unit), which afforded the chromogenic Hg(II) indicator 7. The reaction of the chromogenic Hg(II) indicator 7 was further optimized in DMSO/water (3:7, v/v) (10 mM PBS buffer, pH = 7.0). Compound 7 displays a color change from blue to pale yellow in the presence of Hg(II).

A diastereoselective unique route to cyclopropanes functionalized at all three ring carbon atoms from acyclic vinyl sulfone-modified carbohydrates.

In a departure from the current trend of using metal-catalyzed routes to cyclopropanation, pentosyl and hexosyl vinyl sulfone-modified carbohydrates having the terminal double bond and a suitably positioned leaving group are reacted in a stereoselective fashion with a series of nucleophiles to yield a myriad of cyclopropanes substituted at all three ring carbon atoms.

Densely functionalized chiral pyrroles from endocyclic, exocyclic, and acyclic vinyl sulfone-modified carbohydrates.

A wide range of vinyl sulfone-modified carbohydrates have been prepared as starting materials for the synthesis of polysubstituted chiral pyrroles. All these vinyl sulfones reacted efficiently with ethylisocyanoacetate to generate a plethora of new pyrrole derivatives. Furanosyl rings opened up during pyrrole synthesis, and pyranosyl rings were opened up by reacting the pyrrole with POCl(3)/DMF. This paper also reports one of the most efficient and practical routes for the synthesis of beta-substituted pyrroles.