Synthesis and Crystal Structure of N-[(2S)-4-bromo-2-(L-menthyloxy)-5-oxo-2,5-dihydro-3-furyl]-L-leucine

Starting from（5S）-（L-menthyloxy）-3,4-dibromo-5H-furan-2-one and L-leucine,the title compound N-[（2S）-4-bromo-2-（L-menthyloxy）-5-oxo-2,5-dihydro-3-furyl]-L-leucine 5（C20H32BrNO5,Mr = 446.37） was obtained in one-pot process via the tandem Michael addition-elimination reaction in the presence of potassium hydroxide.The chemical structure and absolute configuration of the title compound were confirmed via rotation,UV-Vis,FT-IR,1H NMR,13C NMR,MS and elemental analysis,especially by the X-ray single-crystal diffraction.The crystal crystallizes in an orthorhombic system,space group P212121 with a = 12.5249（16）,b = 19.005（3）,c = 19.719（3） ,V = 4693.7（10） 3,Z = 8,Dc = 1.263 g/m3,μ = 1.778 mm-1,F（000） = 1872,the final R = 0.0617 and wR = 0.1576 for 3967 observed reflections（I 2σ（I））.X-ray analysis reveals that the title compound has two independent molecules in the asymmetric part of the unit cell with the two five-membered furanones being almost planar.The essential part of the electron delocalization is concentrated in the N（1）,C（3）,C（1）,C（37） and O（7） region and N（2）,C（28）,C（27）,C（30） and O（4） region in the other molecule respectively,but does not take place at the expense of delocalization within the ester function.

One-Step Microemulsion-Mediated Hydrothermal Synthesis of Nanocrystalline TiO₂

Nanocrystalline TiO2 powders with high photocatalytic activity were prepared by one-step microemulsion-mediated hydrothermal method using tetrabutylorthotitanate (TiO(C4H9)4, TBOT) as precursor. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) specific surface area measurements. The effects of the oil/water ratio and hydrothermal temperature on the microstructures and photocatalytic activity of the TiO2 powders were investigated. The results suggest that increasing the oil/water emulsion ratio significantly decreased the particle size of the as-prepared TiO2 powders and improved the photocatalytic activity. With hydrothermal temperature increasing, the average crystallite size increased and the photocatalytic activities of TiO2 powders decreased.

Effect of H_3BO_3 on the phase stability and long persistence properties of Sr_(3.96)Al_(14)O_(25):Eu_(0.01)^(2+), Dy_(0.02)^(3+) phosphor

Sr3.96Al14025：Eu2＋,Dy3＋ long persistent materials with different weights of H3BO3 prepared by the high temper- ature solid-state reaction method were characterized by X-ray powder diffraction （XRD）, scanning electronic microscopy （SEM）, photoluminescence spectra （PL）, and thermoluminescence （TL）. The results of XRD indicate that the 3% addition of H3BO3 favorable for the formation of pure phase Sr4Al14025, and SrAl12O19 was generated when there is a low con- tent or high content of H3BO3. The average grain sizes of samples grow bigger with an increase of H3BO3. PL spectra show that the emission peak does not shift evidently and the emission intensity changes little, indicating that the different amount of H3BO3 has little influence on the crystal field. The decay characteristics and TL measurement show that H3BO3 affects the afterglow properties of Sr3.96Al14025：Eu2＋,Dy3＋, because the increasing H3BO3 leads to more defects in the Sr4Al14025 matrix.

Photo-induced morphology transition of a multifunctional photochromic bisthienylethene molecule with switchable aggregation-induced emission

A novel multifunctional molecule BTE-CNPH was designed and synthesized by connecting 2-(3′,5′-bis(trifluoromethyl)-biphenyl-4-yl)-2-cyanovinyl group to both side of the bisthienylethene(BTE), which exhibited excellent aggregation-induced emission(AIE) and bistable photochromism. High-contrast(>60) reversible fluorescence switching was achieved in the 1 D nanowires, solid of BTE-CNPH and also in a polymethyl methacrylate(PMMA) film loaded with 1% BTE-CNPH under the alternative irradiation by 365 nm and visible light. Interestingly, the nanowire-like assembly morphology of BTE-CNPH in aqueous tetrahydrofuran(THF) solution of specific concentration was observed to translate into amorphous pieces gradually upon prolonged irradiation by the 365 nm, accompanying with photo-tunable AIE emission.

C@Ag/TiO₂: A Highly Efficient and Stable Photocatalyst Active under Visible Light

In this paper, preparation and characterization of C@Ag/TiO2 nanospheres compound photocatalysts was reported. C@Ag nanosphere was firstly synthesized via hydrothermal reaction, and followed by a sol-gel process to obtain the functionalized C@Ag/TiO2 nanosphere which has highly efficient visible light catalytic ability towards methyl orange (MO). The morphology of the obtained compound was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technologies. From which we can see that the as-prepared samples show a spherical structure with a diameter of approximately 200 nm, and the silver particle in core was about 10 nm. The catalytic ability of the synthesized photocatalysts under visible light irradiation shows that C@Ag/TiO2 possesses higher photocatalytic activity towards MO degradation than that of N-P25 (TiO2). Furthermore, the C@Ag/TiO2 photocatalysts exhibited excellent reusability with almost no change after five runs. Finally, the possible photocatalytic mechanism of catalyst under visible light was discussion and proposed.

Polyglutamic Acid Based Polyanionic Shielding System for Polycationic Gene Carriers

For the purpose of increasing the in vivo stability of polycation gene carriers, we prepared a kind of p H-sensitive poly（ethylene glycol）-poly（γ-benzyl-L-glutamate-co-glutamic acid）（PEG-PGA（65）, 65 denotes the molar ratio of glutamic acid in poly（γ-benzyl-L-glutamate-co-glutamic acid））. PEG-PGA（65） showed low cytotoxicity and could shield the positive charge of DNA/PEI（1：1） polyplexes efficiently. The transfection was enhanced due to the partially charge shielding in He La cell line at pH of 7.4. There was almost no transfection efficiency when the surface charge of the ternary particles turned to negative at p H of 7.4. However, the transfection efficiency recovered a lot by culturing at p H of 6.0 at the beginning of transfection. Confocal microscopic observation and flow cytometry results showed DNA/PEI polyplexes should be efficiently released and endocytosized at p H 6.0, because of the p H triggered deshielding action of PEG-PGA（65）. Due to the good biocompatibility and suitable p H triggered shielding/deshielding property, PEG-PGA（65） could be a potential shielding system for polycationic gene carriers used in vivo.