Wen-Ping Jia

Reaction-based fluorescent probe for selective discrimination of thiophenols over aliphaticthiols and its application in water samples.

The development of highly sensitive and selective detection techniques for the discrimination of relevant toxic benzenethiols and biologically active aliphatic thiols is of considerable importance in the fields of chemical, biological, and environmental sciences. In this article, we describe a new design of reaction-based fluorescent probe for discrimination of thiophenols over aliphaticthiols through intramolecular charge transfer pathways using N-butyl-4-amino-1,8-naphthalimide as a fluorophore, the strongly electron-withdrawing 2,4-dinitrobenzenesulfonamide group as a recognition unit, and 2,3-dihydroimidazo-[1,2-a] pyridine moiety as a linker. This rational design not only affords finely tunable spectroscopic properties by adding 2,3-dihydroimidazo-[1,2-a] pyridine moiety but also provides the chance to regulate the selectivity and sensitivity of the probe due to the formation of a new type of potentially reversible sulfonamide bond through 4-dimethylaminopyridine-like resonance. The developed probe displayed high off/on signal ratios, good selectivity, and sensitivity with a detection limit of 20 nM and a relative standard deviation of 1.7% for 11 replicate detections of 0.33 μM thiophenol and was successfully applied to the determination of thiophenols in water samples with quantitative recovery (from 94% to 97%) demonstrating its application prospect for thiophenols sensing in environmental and biological sciences.

Selective removal of 2,4-dichlorophenoxyacetic acid from water by molecularly-imprinted amino-functionalized silica gel sorbent

A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared by a surface imprinting technique in combination with a sol-gel process. The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR, nitrogen adsorption and static adsorption experiments. The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol (2,4-DCP) mixture or using an aqueous 2,4-D and 2,4-dichlorophenylacetic acid (DPAC) mixture. The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18, the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9. The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent. The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D, 73% of binding capacity (200 mg/L 2,4-D onto 20 mg of imprinted sorbent) was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HCl (V:V = 1:1). In a test of five extraction/stripping cycles, the adsorption capacity of the sorbent was all above 93% of that of the fresh sorbent. Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.

Gold Promotion of MCM-41 Supported Ruthenium Catalysts for Selective Hydrogenation of α,β-Unsaturated Aldehydes and Ketones

In the challenging α,β-unsaturated aldehydes and ketones hydrogenation to unsaturated alcohols (UA), Ru–Au/MCM-41 exhibits superior high activity and selectivity compared with monometallic Ru. TEM and XRD measurements were applied to characterize as-prepared Ru/MCM-41 and Ru–Au/MCM-41 catalysts. The results indicated that the addition of Au significantly improved the dispersion of the metallic Ru components, thus enhancing the activity of the catalyst. The enhancement of selectivity to UA could be attributed to the interaction of Ru and Au components in the support and the morphology effect of Ru, which are revealed by in-suit DRIFTS, H2-TPD, XPS, and FTIR measurements. The morphological and electronic aspects of Ru particles lead to a favorable adsorption of C=O bond versus C=C bond. A dramatic increase in activity and selectivity of the reactions were observed upon the addition of Au, suggesting that the significant synergistic effects between Ru and Au play an important role in the activity and selectivity of the reaction. It is the first time that chemoselective hydrogenation of α,β-unsaturated aldehydes and ketones were studied on Ru–Au/MCM-41 catalysts.Graphical Abstract