Bixia Yao

A facile microwave-assisted fabrication of fluorescent carbon nitride quantum dots and their application in the detection of mercury ions.

A facile microwave-assisted solvothermal method was used to prepare fluorescent carbon nitride quantum dots (CNQDs) using oleic acid as the reaction media at moderate reaction temperature in a short time (5 min). Citric acid monohydrate and urea were used as the precursors. The as-prepared CNQDs were characterized by multiple analytical techniques. The CNQDs exhibited an uncommon excitation wavelength-dependent fluorescence with two maximum emission peaks at 450 and 540 nm. The CNQDs with a quantum yield of 27.1% could serve as an effective fluorescent sensing platform for label-free sensitive detection of Hg(2+) ions with a detection limit of 0.14 μM. This method was also applied to the detection of Hg(2+) ions in tap water samples.

Unusual chromatographic enantioseparation behavior of naproxen on an immobilized polysaccharide-based chiral stationary phase

Enantioseparation of naproxen was performed on an immobilized polysaccharide-based chiral stationary phase (CSP), Chiralpak IA, in the normal-phase mode. The effects of polar alcohol modifier in mobile phase and column temperature on retention, enantioseparation, and elution order were investigated. Two unusual phenomena were observed. One was solvent-induced reversal of elution order for the two enantiomers. Not only the type but also the content of polar alcohol modifier could induce the reversal. Another uncommon phenomenon was peak deformation under some chromatographic conditions.

One-pot fabrication of hollow cross-linked fluorescent carbon nitride nanoparticles and their application in the detection of mercuric ions.

Hollow cross-linked fluorescent carbon nitride nanoparticles (CNNPs) were fabricated via a facile one-pot solvothermal process. The obtained CNNPs were characterized by multiple analytical techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), solid-state nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The excitation-dependent fluorescence emission spectra showed significant differences for the CNNPs derived from various proportions of citric acid monohydrate and urea. The fluorescence quantum yield of the obtained CNNPs could reach 31%. The CNNPs exhibited good fluorescence quenching selectivity to mercuric ions. Concentration experiments showed that there existed two parts of linear relationship between fluorescence intensity and concentration of Hg(2+) ions in the range of 0.1-8 and 8-32 μM. The limit of detection (LOD) was estimated to be 0.094 μM. This method can be applied to the detection of Hg(2+) ions in tap water samples.

Development of a Composite Chiral Stationary Phase from BSA and β-Cyclodextrin-Bonded Silica

A composite chiral stationary phase (CSP) derived from bovine serum albumin (BSA) and β-cyclodextrin (CD)-bonded silica was prepared. 2,4,6-Trichloro-1,3,5-triazine was used as a cross-linker. The obtained CSP was applied to the enantioseparation of tryptophan, hydrobenzoin, phenylalanine and mandelic acid. The influences of eluent pH value, organic modifier and column temperature on the retention and enantioseparation were discussed. Tryptophan and hydrobenzoin achieved excellent resolution on the composite CSP. For tryptophan, the highest selectivity, 2.79, was achieved with 1% of methanol at pH 8.0. For hydrobenzoin, the selectivity could reach 1.42. The chromatographic results were compared with that on β-CD-bonded or BSA-immobilized CSP.

(R)-1,1′-Binaphthalene-2,2′-diyl dicinnamate

In the title compound, C38H26O4, two cinnamoyloxy groups are linked in a trans fashion to the two O atoms of optically active (R)-1,10-bi-2-naphthol. The dihedral angle between the mean planes of the two naphthyl groups is 71.8 (1)°. The crystal structure contains intermolecular C—H⋯O and C—H⋯π interactions.