The structure and performance of TiO2-supported Re (Re/TiO2) catalysts for selective hydrogenation of carboxylic acid derivatives have been investigated.
A novel process, i.e., ultrasound-assisted membrane reduction, was introduced and applied to synthesize Ag and Au nanocrystals. High-resolution transmission electronic microscopy and UV-vis spectra were adopted to observe and study the resulting colloids. The nearly spherical Ag and Au nanoparticles with mean diameters of 5.8 and 6.8 nm, respectively, were synthesized with the novel method. The silver nitrates/hydrogen tetrachloroaurate hydrate, sodium borohydride, and poly(N-vinyl-2-pyrrolidone) (PVP) were used as metal precursor, reductant, and stabilizer, respectively. The reverse mixing of silver nitrate and reductant resulted in larger Ag nanoparticles in the range of 5-24 nm. The addition of ethylenediaminetetraacetic acid (EDTA), which may serve as the second protecting agent together with PVP, could reduce the Au particle size to a mean value of 2.6 nm. By varying the NaBH 4 injection rate in the process, a portion of the primary Au crystallites could be self-assembled to form decahedral Au nanocrystals with a diameter of ca. 24 nm. The two-dimensional networked gold nanowires with mean diameters of 5-10 nm could be fabricated by regulating the acidity of the reaction system to pH 10 with aqueous ammonia.
Novel benzenesulfonamide-substituted 1,5-diarylpyrazoles containing phenylacetohydrazide derivatives have been synthesized. Among them, 48 showed best antiproliferative activity against A549 cells and was evaluated as a selective COX-2 inhibitor.
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