基于功能化的金纳米的共振瑞利散射方法手性识别肉碱对映体（英文）

一种不经分离而同时测定手性对映体的简便方案是非常有趣和有用的。提出一种基于共振瑞利散射(RRS)光谱技术手性识别新方法,利用功能化的金纳米粒子(Au NPs)同时检测肉碱对映体。AuNPs的RRS强度很弱,但当Cu~(2+)存在时,RRS强度显著增加。更有趣的是,肉碱对映体均可以降低Cu~(2+)-Au NPs体系的RRS强度,但D-肉碱使RRS降低更多。在最优实验条件下,均有良好的线性关系并有很好的相关系数以及较低的检出限。由此,这种方法可以计算出肉碱对映体的对映体比率和对映体分数。并应用于胶囊样品中肉碱对映体混合物手性识别的研究。该方法不需要复杂的手性修饰处理,并具有简捷低消耗、灵敏度高、选择性好等优点。     

共振瑞利散射探针罗丹明B手性识别肉碱对映体

手性对映体广泛存在于环境和生命体中,手性识别有助于探索手性世界的奥妙和生命过程的机理。共振瑞利散射因其灵敏度高成为了手性识别的一大工具。不经分离而同时测定手性对映体则是手性识别的一大新的探索。最近,我们发现罗丹明B可以作为一种散射探针来同时测定肉碱对映体。根据偏振实验可以证明罗丹明B与肉碱反应体系的共振辐射光是由共振荧光和散射光组成。当肉碱对映体与罗丹明B反应时,罗丹明B的共振瑞利散射会有不同程度的增加。根据罗丹明B响应两种对映体RRS信号的差异,我们可以同时测定肉碱对映体。     

Al~(3+)诱导的金纳米粒子静电自组装及其SERS表征

通过Al 3+静电诱导实现了金纳米粒子(Au NPs)的一维(1D)或二维(2D)程序可控自组装。我们的研究发现,静电组装形成的Au NPs组装体(Au NAs)的尺寸、形貌及其表面等离子体共振(SPR)性质与Al 3+的浓度密切相关,随着Al 3+浓度的增加,Au NPs由孤立的Au纳米粒子组装成一维或二维的纳米阵列。同时,与孤立Au NPs相比,Au NAs因存在更多的"热点"而具有更好的SERS活性,并可以通过调节Al 3+的浓度来调控Au NAs的SERS活性。     

β-环糊精手性识别D/L-樟脑磺酸的NMR研究

利用高分辨液体NMR技术考察了D_2O中β-环糊精与手性药物D/L-樟脑磺酸对映体之间的相互作用, 结果表明樟脑磺酸对映体能够进入β-环糊精的疏水空腔并与之发生手性相互作用. β-环糊精能够手性识别樟脑磺酸对映体. 化学计量关系实验和2D ROESY实验结果表明, 樟脑磺酸对映体的疏水结构只能从β-环糊精疏水空腔的宽口端进入, 并形成化学计量比为1∶1的非对映体络合物.     

两种二苯醚类除草剂在直链淀粉液相色谱手性固定相上的拆分

以硅胶涂敷直链淀粉-三(5-氯-2-甲基苯基氨基甲酸酯)为手性固定相,对两种含有1个手性中心的二苯醚类除草剂2-甲氧基-2-{5-[2-氯-4-(三氟甲基)苯氧基]-2-硝基苯)丙酸甲酯和乳氟禾草灵,进行了色谱分离.考察了流动相中异丙醇和正己烷的体积比对乳氟禾草灵对映体分离的影响.结果显示,这2种二苯醚类除草剂可以同时在Chiralpak AY-H色谱柱上获得较好的手性拆分结果；并对农药对映体与固定相之间的保留机理进行了讨论.     

β-环糊精手性识别D/L-樟脑磺酸的NMR研究

利用高分辨液体NMR技术考察了D₂O中β-环糊精与手性药物D/L-樟脑磺酸对映体之间的相互作用,结果表明樟脑磺酸对映体能够进入β-环糊精的疏水空腔并与之发生手性相互作用. β-环糊精能够手性识别樟脑磺酸对映体. 化学计量关系实验和2D ROESY实验结果表明,樟脑磺酸对映体的疏水结构只能从β-环糊精疏水空腔的宽口端进入,并形成化学计量比为1∶1的非对映体络合物.     

Cu+、Ag+、Au+与乙硫醇的气相化学反应

利用激光溅射-分子束的技术,结合反射飞行时间质谱计,研究了Cu+、Ag+、Au+与乙硫醇的气相化学反应.结果显示这三种金属离子与(CH3CH2SH)n反应形成一系列团簇离子M+(CH3CH2SH)n,且团簇离子尺寸不一样.Ag+、Au+与乙硫醇的反应还生成了(CH3CH2SH)+n,由此推测Cu+、Ag+、Au+与乙硫醇团簇的反应存在两种通道,一种通道是生成M+(CH3CH2SH)n,另一种是生成(CH3CH2SH)+n.Cu+、Au+与乙硫醇的反应还生成了M+(H2S)(M=Cu、Au),但是实验中没有观察到Ag+(H2S),理论计算表明Ag+(H2S)很不稳定.另外,分析产物离子M+(CH3CH2SH)n的强度发现,n=1～2之间存在明显的强度突变现象.     

Cu~+、Ag~+、Au~+与乙硫醇的气相化学反应

利用激光溅射 分子束的技术 ,结合反射飞行时间质谱计 ,研究了Cu+、Ag+、Au+与乙硫醇的气相化学反应。结果显示这三种金属离子与 (CH3 CH2 SH) n 反应形成一系列团簇离子M+(CH3 CH2 SH) n,且团簇离子尺寸不一样。Ag+、Au+与乙硫醇的反应还生成了 (CH3 CH2 SH) +n ,由此推测Cu+、Ag+、Au+与乙硫醇团簇的反应存在两种通道 ,一种通道是生成M+(CH3 CH2 SH) n,另一种是生成 (CH3 CH2 SH) +n 。Cu+、Au+与乙硫醇的反应还生成了M+(H2 S) (M =Cu、Au) ,但是实验中没有观察到Ag+(H2 S) ,理论计算表明Ag+(H2 S)很不稳定。另外 ,分析产物离子M+(CH3 CH2 SH) n 的强度发现 ,n =1～ 2之间存在明显的强度突变现象     

核磁共振氢谱中二苯基乙二胺衍生物手性识别其结构类似物(英文)

本文通过手性二苯基乙二胺与异氰酸酯的衍生化反应,合成了一种C_2对称的手性主体1.该主体可以手性识别其结构类似物:α-苯乙胺(客体2)、α-对甲氧基苯乙胺(客体9)以及它们的衍生物(客体3～8和10～13).高分辨核磁共振氢谱(~1H NMR)显示了对映体识别中主客体间的氢键作用.结果表明,除含2个NO_2的客体7和12外,主体1可以较易识别含有两个伯胺的脲和酰胺衍生物.研究还发现,主体1对脲衍生物2、9比对酰胺衍生物有更强的氢键作用,此外主体1对(R)和(S)-脲衍生物中的CHCH_3基团也有更高的辨识能力.     

手性固定相NP-HPLC拆分达非那新中间体对映体

采用多糖衍生物手性色谱柱,建立了正相高效液相色谱法(NP-HPLC)拆分达非那新中间体对映体.考察了该对映体在不同手性固定相上的分离趋势及保留顺序,以及流动相组成对该中间体对映体的分离度和洗脱顺序的影响.结果表明:用Chiralpak AD和Chiralcel OJ柱均能实现对映体的有效分离,为达非那新中间体的光学纯度...     

Chiral Ag and Au Nanomaterials Based Optical Approaches for Analytical Applications

Sensing of chiral compounds has gained great attentions for many decades. Chiral nanomaterials with a greater surface area, optical properties, and stability have however not been well realized in this field. Herein, strategies for the preparation of chiral Ag and Au nanomaterials are focused upon, including Ag and Au nanoparticles conjugated with chiral molecules with/without containing fluorophores, chiral nanoassemblies of Ag and Au nanoparticles, and chiral Ag and Au nanoclusters. The chirality of nanomaterials originates from their core and/or ligand, meanwhile that for nanoassemblies results from their complex spatial configuration. An emphasis is given to circular dichroism, colorimetry/UV–vis absorption, and fluorescence detection modes for sensing enantiomers and achiral analytes using the chiral Ag and Au nanomaterials. Several interesting examples for quantitation of DNA, proteins, peptides, drugs, and pollutants are provided to highlight their potential as sensitive and selective nanomaterials for enantiomer recognition and sensing of achiral analytes. Several important issues to be solved when using chiral nanomaterials for chiral recognition are specified. Some strategies for improving the sensitivity and selectivity of chiral nanomaterials for chiral recognition are suggested. The aim is to bring more attention to the potential of chiral nanomaterials for sensing important analytes such as chiral drugs.     

DNA酶裂解-纳米金共振瑞利散射光谱法测定痕量Cu2+

在pH 7.0HEPES(4-羟乙基哌嗪乙磺酸)缓冲溶液中和0.19mol.L-1 NaCl存在下,单链底物DNA(SS)和酶链DNA(ES)在80℃杂交形成双链DNA(dsDNA)。Cu2+可切割dsDNA中的底物链释放出单链DNA(ssDNA),此ssDNA与金纳米粒子(NG)作用形成NGssDNA结合物不被NaCl聚集,而未保护的NG聚集形成较大粒径的聚集体(NGA),在627nm处有一个较强的共振瑞利散射峰。随着Cu2+浓度的增大,该共振瑞利散射峰降低,其降低值ΔI与Cu2+浓度在15～1 250nmol.L-1范围呈线性关系,其回归方程为ΔI=0.17c-2.3,线性相关系数为0.989 5,检出限为8nmol.L-1。据此建立了一个高灵敏、高选择性、简便测定Cu2+的共振瑞利散射光谱分析法。该法用于水样中Cu2+的检测,结果满意。     

Selective oxidative etching of CTAC-stabilized multi-branched gold nanoparticles: application in spectral sensing of iodide ions

Multi-branched gold nanoparticles (Mb Au NPs) with sharp tips are considered excellent candidates for broad applications in plasmonics, optical sensing, and field enhancement. Here, Mb Au NPs were prepared by a one-step seedless synthesis method in the presence of Triton X-100. CTAB and CTAC were used to replace TX-100 for improving the stability of Mb Au NPs. The effect of halide ions (Cl, Br, I) on oxidative etching of CTAB- and CTAC-stabilized Mb Au NPs were investigated. The results showed that both Br^? and I^? could trigger the etching of CTAB-stabilized Mb Au NPs. However, only I^? triggered the etching of CTAC-stabilized Mb Au NPs even without catalysis of Cu²⁺. The selectivity of I^? to the etching of CTAC-stabilized Mb Au NPs led to the decrease of plasmon intensity. Based on such a unique property, we demonstrated a spectral detection method for I^? using the CTAC-stabilized Mb Au NPs as nanoprobes. The intensity decrease of a plasmon peak had a linear correlation with the concentration of I^? in the range of 1.8–18 μM, with a detection limit of 0.41 μM. The proposed method also showed a high selectivity towards I^? over other existing anions. Therefore, this spectral method offers the possibility to rapidly distinguish I^? in analytical contexts in which halide ions coexist.     

Adsorption on nanostructured chiral surfaces studied by the Monte Carlo method

A Monte Carlo (MC) lattice gas model of adsorption of a racemic mixture of enantiomers of 1,2-dimethylcyclopropane on a chiral surface with different spatial distribution of active sites was proposed. The calculations were performed on a square lattice for both stepped chiral surfaces and smooth surfaces with chiral patterns of active sites. The adsorbing molecules were assumed to be rigid structures of two types being mirror images one of another. Regardless of the enantiomer type, each molecule was composed of four segments occupying four lattice sites. The chiral surfaces were exposed to equimolar mixture of enantiomers whose individual equilibrium adsorption isotherms were calculated using standard Grand Canonical MC technique. The major purpose of the simulation was to examine how the structure of the surface affects separation of enantiomers, that is, to determine enantioselectivity defined as the ratio of their adsorbed amounts. Additionally, comparison of the enantioselectivities corresponding to the stepped and smooth surfaces was made.     

不同形貌金纳米粒子的制备及其表面增强拉曼散射效应的研究

不同形状的金纳米粒子在表面增强拉曼散射(surface enhanced Raman scattering,SERS)中有不同的增强效果,多面体金纳米粒子具有多角结构,显示出比金纳米板更为明显的增强效果,近年来对其合成和性质的研究备受关注。该研究探究了十二面体,二十面体,三角板,球形四种形状的金纳米粒子在SERS中不同的增强效果。分别采用硼氢化钠还原法和以N,N-二甲基甲酰胺(DMF)为还原剂制备金三角纳米片和二十面体金纳米粒子,又以二十面体金纳米粒子为种子制备出十二面体金纳米粒子,并分别以以上三种不同形貌的金纳米粒子及球形金溶胶为基底,4-巯基吡啶,对巯基苯甲酸为探针分子检测了其在不同激发波长下的增强效果。透射电子显微镜结果表明金三角纳米板的平均边长为130nm,二十面体和十二面体金纳米粒子的粒径分别为100和120nm。三者的紫外可见吸收峰分别在589,598和544nm处。表面增强拉曼散射结果表明金多面体比金三角纳米板表现出更好的增强效果。     

Fabrication and characterization of a Cu seed layer on a 60-nm trench-patterned SiO2 substrate by a self-assembled-monolayer (SAM) process

Continuous electroless deposition of a 10-nm thick layer of Cu was successfully performed on a SiO₂/Si substrate coated with a 3-nm Au catalytic layer. The Au catalytic layer was formed by a self-assembled monolayer (SAM) process terminated with NH₂ headgroups, upon which negatively charged Au particles were deposited via electrostatic interaction with the positively charged NH₂-SAM. The Au and NH₂-SAM layers were analyzed by X-ray photoelectron spectroscopy (XPS) and contact angle analysis. Atomic force microscopy, field emission scanning electron microscopy, and XPS revealed that the Cu layer formed by this electroless processes had good step-coverage, small grain size, and excellent adhesion to the substrate. The proposed process is a very promising method for fabrication of a conductive Cu seed layer in a 60-nm trench-pattern.     

Enantioseparation on a chiral nanostructured surface: Effect of molecular shape

In this paper we use the Monte Carlo simulation method to study adsorption of chiral molecules on a solid surface with periodic distribution of active sites. Namely, equilibrium adsorption of a racemic mixture of enantiomers represented by homonuclear tetramers is modeled on a square lattice with a chiral pattern of active sites. We consider two possible chiral structures of the tetramers which differ only by chain geometry but have equal adsorption energies. The effect of the chain geometry on the effectiveness of separation is assessed by comparing the corresponding adsorption selectivities obtained from the simulations. We present results of model calculations in which the parameters do not refer to any particular experimental system. These results indicate that the model chiral surface can, in general, adsorb preferentially the complementary enantiomer, regardless of its chain conformation. Specifically, it was shown that changes in the tetramer geometry, from S-shaped to -shaped, lead to marginal changes in the shape of both single component and mixed adsorption isotherms calculated for the enantioselective surface. In this context, the enantiomer separation on the surface proposed in this work was shown to be insensitive to molecular shape of the adsorbing species.     

High-resolution solid-state NMR spectroscopy as a tool for investigation of enantioselective inclusion complexation

In this paper, we showed the application of solid state-NMR (SS NMR) spectroscopy in structural studies of chiral compounds employing sample of (E)-1-diphenylphosphinoylpent-3-en-2-ol 1 as a model compound. Racemate of 1 was fully characterized by NMR techniques (both in liquid and solid phase) and X-ray crystallography. Theoretical calculations employing the GIAO approach were used to explain the influence of hydrogen bonding on 31P NMR shielding parameter in racemate. Enantioselective inclusion complexation (EIC) method with TADDOL as host molecule was applied to separate of enantiomers. The formation of host-guest complex and decomplexation procedure was monitored by means of the SS NMR. The liquid-state NMR, due to similarity of 13C and 31P spectral parameters was not able to distinguish racemate from enantiomer. In the solid phase, owing to distinction of hydrogen bonding and molecular packing in the crystal lattice, racemate and enantiomers were easy recognized by NMR spectroscopy.     

Green synthesis and characterization of Au@Pt core–shell bimetallic nanoparticles using gallic acid

In this study, we developed a facile and benign green synthesis approach for the successful fabrication of well-dispersed urchin-like Au@Pt core–shell nanoparticles (NPs) using gallic acid (GA) as both a reducing and protecting agent. The proposed one-step synthesis exploits the differences in the reduction potentials of AuCl₄⁻ and PtCl₆²⁻, where the AuCl₄⁻ ions are preferentially reduced to Au cores and the PtCl₆²⁻ ions are then deposited continuously onto the Au core surface as a Pt shell. The as-prepared Au@Pt NPs were characterized by transmission electron microscope (TEM); high-resolution transmission electron microscope (HR-TEM); scanning electron microscope (SEM); UV-vis absorption spectra (UV-vis); X-ray diffraction (XRD); Fourier transmission infrared spectra (FT-IR). We systematically investigated the effects of some experimental parameters on the formation of the Au@Pt NPs, i.e., the reaction temperature, the molar ratios of HAuCl₄/H₂PtCl₆, and the amount of GA. When polyvinylpyrrolidone K-30 (PVP) was used as a protecting agent, the Au@Pt core–shell NPs obtained using this green synthesis method were better dispersed and smaller in size. The as-prepared Au@Pt NPs exhibited better catalytic activity in the reaction where NaBH₄ reduced p-nitrophenol to p-aminophenol. However, the results showed that the Au@Pt bimetallic NPs had a lower catalytic activity than the pure Au NPs obtained by the same method, which confirmed the formation of Au@Pt core–shell nanostructures because the active sites on the surfaces of the Au NPs were covered with a Pt shell.     

金纳米粒子的制备及其表面增强拉曼散射效应的研究

采用多巴胺化学还原法制备了分散性良好的纳米金溶胶,并检测了其作为表面增强拉曼散射(Surface Enhanced Raman Scattering,SERS)基底的性质。粒度和透射电子显微镜测试结果表明金溶胶为平均粒径30nm左右的球形颗粒,并且紫外-可见特征吸收峰出现在520nm,为典型的金纳米颗粒特征吸收峰。以罗丹明6G(R6G)为探针分子证明了金溶胶良好的SERS增强效果,用金溶胶对除草剂敌草快(DQ)进行检测,最低检测限可达1×10-7 mol/L。结果表明所制备的金溶胶具有良好的表面增强拉曼散射活性。