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951.
Bin Yang Junsheng Chen Songqiu Yang Feng Hong Lei Sun Peigeng Han Prof. Dr. Tõnu Pullerits Prof. Dr. Weiqiao Deng Prof. Dr. Keli Han 《Angewandte Chemie (International ed. in English)》2018,57(19):5359-5363
Lead‐free perovskite nanocrystals (NCs) were obtained mainly by substituting a Pb2+ cation with a divalent cation or substituting three Pb2+ cations with two trivalent cations. The substitution of two Pb2+ cations with one monovalent Ag+ and one trivalent Bi3+ cations was used to synthesize Cs2AgBiX6 (X=Cl, Br, I) double perovskite NCs. Using femtosecond transient absorption spectroscopy, the charge carrier relaxation mechanism was elucidated in the double perovskite NCs. The Cs2AgBiBr6 NCs exhibit ultrafast hot‐carrier cooling (<1 ps), which competes with the carrier trapping processes (mainly originate from the surface defects). Notably, the photoluminescence can be increased by 100 times with surfactant (oleic acid) added to passivate the defects in Cs2AgBiCl6 NCs. These results suggest that the double perovskite NCs could be potential materials for optoelectronic applications by better controlling the surface defects. 相似文献
952.
Fluorogenic Ag+–Tetrazolate Aggregation Enables Efficient Fluorescent Biological Silver Staining
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Dr. Sheng Xie Alex Y. H. Wong Dr. Ryan T. K. Kwok Dr. Ying Li Dr. Huifang Su Dr. Jacky W. Y. Lam Prof. Dr. Sijie Chen Prof. Dr. Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2018,57(20):5750-5753
Silver staining, which exploits the special bioaffinity and the chromogenic reduction of silver ions, is an indispensable visualization method in biology. It is a most popular method for in‐gel protein detection. However, it is limited by run‐to‐run variability, background staining, inability for protein quantification, and limited compatibility with mass spectroscopic (MS) analysis; limitations that are largely attributed to the tricky chromogenic visualization. Herein, we reported a novel water‐soluble fluorogenic Ag+ probe, the sensing mechanism of which is based on an aggregation‐induced emission (AIE) process driven by tetrazolate‐Ag+ interactions. The fluorogenic sensing can substitute the chromogenic reaction, leading to a new fluorescence silver staining method. This new staining method offers sensitive detection of total proteins in polyacrylamide gels with a broad linear dynamic range and robust operations that rival the silver nitrate stain and the best fluorescent stains. 相似文献
953.
Dr. Alexander G. Tskhovrebov Dr. Richard Goddard Prof. Alois Fürstner 《Angewandte Chemie (International ed. in English)》2018,57(27):8089-8094
Two highly labile silver carbene cluster complexes are described, which are unique in that they mark the transition point at which the carbene center transmutes from a fairly common NHC‐like nucleophilic behavior to an electrophilic character befitting reactive silver carbene intermediates of relevance in various catalytic transformations. This amphoteric character is the distinguishing attribute of a μ‐bridged donor/donor carbene entity that connects two silver atoms of triangular or tetrahedral metallic core units. 相似文献
954.
Silver‐Catalyzed Efficient Synthesis of Oxindoles and Pyrroloindolines via α‐Aminoalkylation of N‐Arylacrylamides with Amino Acid Derivatives
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α‐Aminoalkylation of N‐arylacrylamides with amino acid derivatives was achieved by silver‐catalysis in moderate to high yields. The reaction provides an efficient strategy for the synthesis of functionalized oxindoles, and is suitable for a wide range of N‐arylacrylamides and amino acids, both of which are inexpensive and readily available. The oxindoles obtained were readily transformed into densely functionalized pyrroloindolines by deprotection and cyclization in one pot. 相似文献
955.
Aditya Dutt 《Analytical letters》2018,51(7):1071-1086
The application of cysteine-capped silver nanoparticles synthesized using green tea as the reducing agent to immobilize lipase has been reported in the present work. The reducing property of green tea is due to the presence of polyphenolic compounds in its extract which are not oxidized at ambient atmospheric conditions and hence is a suitable reducing agent for green synthesis of nanoparticles. Cysteine-capped silver nanoparticles were synthesized under alkaline conditions by reducing the silver salt by green tea extract in the presence of cystine. Various parameters such as the cystine concentration, pH, temperature, and amount of reducing agent were standardized and their effect on the synthesis process has been initially evaluated by surface plasmon resonance peak analysis. Furthermore, the synthesized nanoparticles were also characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The particle size analysis revealed the average size of the particles to be around 20?nm. The glutaraldehyde-deactivated amino group on cysteine-capped nanoparticles was used to immobilize lipase on its surface. Both crude and immobilized lipases were checked for activity and protein content under standard assay conditions and their activity was found to be 37.7 and 24.9?U?mL?1, respectively. The lipase nanoparticle bioconjugates exhibited a good shelf life of 60 days with a marginal decrease in activity. The bioconjugates showed 15% loss in its initial activity at the end of five reusability cycles. This immobilized reusable system has the potential to be utilized for various applications pertaining to the exploitation of lipase in various industries. 相似文献
956.
Glycinol是大豆中主要的植物抗毒素和植物雌激素glyceollins的直接前体,是研究大豆中异戊烯转移酶必需的重要底物。该研究以新鲜大豆为原料,采用硝酸银诱导大豆子叶使glycinol 在其中累积,再用甲醇提取,经制备高效液相色谱分离获得单一成分;经液相色谱/四极杆-飞行时间串联质谱及紫外光谱鉴定,并与标准品对照,确定所获得的单一成分为glycinol。采用该分离方法可从390 g鲜重的大豆中分离得到100 mg高纯度的glycinol。该研究提供了一种分离纯化和较大量制备glycinol 的方法。 相似文献
957.
硒代胱氨酸和硒代蛋氨酸电化学检测的比较 总被引:7,自引:0,他引:7
对硒代胱氨酸 (SeCys)和硒代蛋氨酸 (SeMet)在银电极上的电化学性质、电极反应机理及检测灵敏度等方面进行比较研究。实验表明 ,两者在pH9.5的硼砂 氢氧化钠介质中 ,于 -0 .62V和 -0 .68V(vs.SCE)处均存在一对氧化还原峰 ,电化学行为相似 ,两者具有良好的线性范围和低检出限 ,SeMet比SeCys具有更高的检测灵敏度。在相同的实验条件下 ,比较了含硫氨基酸与含硒氨基酸的电化学响应 ,含硫氨基酸的检测灵敏度远低于含硒氨基酸 相似文献
958.
959.
A new polynuclear silver complex with bridging diphorsphine ligand has been synthesized and characterized by :single cryatsl X-ray diffraction method The compound crystallizes in the triclinic space group P1 with a=1.27489, b=1.34715, c=1.47015 nm; α=59.747, β=63.949, γ=70.196°; V=1.9369 nm. The simplest formularis [Ag_4· dppe)_3(NO_3)_4], Mr=1874.79, D_c=1.607 g·cm~(-3), Dm=1.62 g·cm~(-3), μ(MoKa)=11.69 cm~(-1), F(OOO)=942. The structure was solved by conventional heavy-atom techniques and refined by full-matrix least squares to give discrepany indices of R=0.048 and RW=0.060(W=1/[σ(Fo)~2+(PWT*Fo)~2+QWT]-Fo) for 5052 reflections. An empirical absorption correction program DIFABS was performed.Silver atoms are linked by bridging ligands of dppe and nitrate, forming a network extending in space. Each structural unit contains two binuclear subunits, of which silver atoms are bridged by nitrates. The two subunits are connected by one dppe ligand. Silver atoms are not equivalent in subunit and one of the nitrates functions not only as a monodentate bridging ligand, but also as an asymmetric bidentate chelating lingand. All coordinate configurations of silver are shown as distorted tetrahedron. 相似文献
960.
报导了双(二苯基膦)丁烷的双核银配合物-[Ag(Ph_2PCH_2CH_2CH_2CH_2PPh_2)-(NO_3)]_2的合成及晶体结构分析。晶体属于单斜晶系,空间群为P2_1/n,晶胞参数为:a=12.821(3),b=11.244(9),c=19.386(9),β=105.94(3)°,V=2687.2~3,Z=2,D_c=1.474g/cm~3,M_r=1192.7,F(000)=1216,μ=8.873cm~(-1)。晶体结构由直接法和Fourier合成解出,使用对角块矩阵和全矩阵最小二乘法对原子参数进行修正,最后偏离因子R=0.056,R_w=0.068,其中2634个I>3σ(Ⅰ)的可观察点参加了结构修正,单晶结构分析结果表明,在该配合物中,配体双(二苯基膦)丁烷(dppb)中的磷原子直接与银离子配位,硝酸根也以双齿配位形式存在,中心银离子的配位采用畸变的四面体构型,整个分子是一个二聚物。 相似文献