基于小分子的汞离子荧光探针*

汞离子（Hg²⁺）作为一种极具生理毒性的化学物质,其检测方法在传感领域得到了广泛的研究。荧光探针由于具有高效灵敏、快速便捷检测等优点而成为Hg²⁺检测的重要手段之一。通过Hg²⁺与探针特征的结合位点作用,引起其光物理性质的变化,从而实现对Hg²⁺的高选择性识别。本文综述了近年来小分子Hg²⁺荧光探针的研究进展。文中着重总结了Hg²⁺荧光探针分子的设计原理、检测机制及应用方法;评述了这些化合物的结构和检测性能之间的关系;最后展望了Hg²⁺荧光探针的研究和发展方向。     

检测汞离子的比色-荧光双通道探针的设计合成及应用

以7-羟基吩恶嗪酮(试卤灵)为荧光团、硫代甲酸苯酯为汞离子(Hg²⁺)识别基团,经一步简单有机合成反应,制备了比色-荧光双通道探针NMP。采用核磁共振氢谱(¹H NMR)、核磁共振碳谱(¹³C NMR)和高分辨率质谱(HRMS)表征了探针结构,利用吸收光谱和荧光发射光谱测试了探针对Hg²⁺的选择性和灵敏度。光谱测试结果表明,探针对Hg²⁺具有较好的选择性和检测灵敏度,检出限(3σ)为17 nmol/L。反应溶液由淡黄色变为紫红色,可对溶液中Hg²⁺进行比色检测,并可用于实际水样中Hg²⁺的检测。采用CCK-8法测试了探针的细胞毒性,结果表明,在探针浓度低于10μmol/L时,细胞存活率高于90%。共聚焦荧光显微成像结果表明,探针具有较好的细胞通透性,可对细胞内Hg²⁺进行荧光成像。     

基于氮化碳量子点/罗丹明B系统检测汞离子的比率荧光探针

通过一步水热法,以柠檬酸和尿素为原料,制备了蓝色氮化碳量子点(CNQDs),并对CNQDs的粒径分布、元素组成、形貌结构及表面官能团进行了表征,考察了CNQDs的光谱性质。以CNQDs为母体与罗丹明B(RhB)构成比率荧光探针CNQDs/RhB,基于CNQDs/RhB(447 nm/581 nm)的荧光强度比值F₀=(F₄₄₇/F₅₈₁)的变化情况对汞离子(Hg²⁺)进行定量测定,具有高选择性和灵敏性。结果显示,该探针对Hg²⁺的检测线性范围为2～40μmol/L,检出限为1.95μmol/L。常见的阴离子和阳离子对CNQDs/Rh B检测Hg²⁺基本无影响,并对该比率型荧光探针的检测机制进行了探究。最后,将该探针应用于实际水样中Hg²⁺的检测,说明该探针具有潜在的应用价值。通过研究,对Hg²⁺的检测提供了新的思路,也预示了该荧光探针在水环境检测方面具有广阔的应用前景。     

一种基于二氰基异佛尔酮的近红外汞离子荧光探针的合成与应用

以二氰基异佛尔酮和4-二乙氨基水杨醛为原料,通过两步反应合成了一种具有近红外发射(675 nm)的荧光探针SAM-S,并对其结构进行了表征。此探针在甲醇/4-羟乙基哌嗪乙磺酸(HEPES)(1∶1,V/V,pH=7.4)溶液中表现出弱荧光,加入Hg²⁺后荧光显著增强,基于此建立了检测Hg²⁺的新方法。本方法具有选择性好、抗干扰能力强、检出限低(0.49μmol/L)等优点。采用此探针检测湖水和自来水中Hg²⁺的含量,加标回收率在99.9%～104.8%之间。探针SAM-S可制作成荧光墨水,有望用于商标包装;由于SAM-S的毒性较低,因此可用于活细胞中Hg²⁺的荧光成像。     

氮硫掺杂碳点的制备及检测铜离子

以柠檬酸为碳源,通过水热合成制备N、S掺杂的蓝色荧光碳点（NS-CDs）,用于实际样品中铜离子检测。采用高分辨率透射电子显微镜、X射线衍射光谱、红外吸收光谱、X射线光电子能谱、荧光光谱对其结构、组成和光学性质进行表征。结果表明,NS-CDs分散性好,尺寸分布在0.6~2.2 nm之间,具有无定形碳的结构;碳点表面含有羟基、羧基、酰胺等官能团,C、N、O和S元素质量分数别为54.01%、24.49%、19.39%及2.11%;该碳点具有良好的耐盐性、pH稳定性、光稳定性,其荧光量子产率为25%。基于Cu²⁺离子与碳点表面多个官能团发生相互作用形成聚集的网络结构,导致荧光猝灭的现象,建立了检测Cu²⁺的荧光分析新方法,本方法对Cu²⁺离子具有良好的选择性和较高的灵敏度,在0.2~10、10~50和50~100 μmol/L范围均有良好的线性响应,检出限为41 nmol/L（S/N=3）满足《土壤环境质量标准》对土壤中Cu²⁺检测国家标准的要求（6.25 mmol/L）。测定了实际土壤中Cu²⁺的含量,检测结果为2.55 μmol/L,加标回收率在104.9%～105.6%之间,实现了Cu²⁺的快速、灵敏、高选择性检测。     

基于铜离子介导的金银双金属纳米簇荧光探针检测草甘膦

基于铜离子(Cu²⁺)与巯基十一烷酸保护的金银双金属纳米簇(AuAgNCs@11-MUA)表面羧基以及草甘膦之间的竞争结合作用,构建了一种简单、灵敏的“turn-on”荧光方法用于草甘膦的定量检测。Cu²⁺可与AuAgNCs@11-MUA表面的羧基结合,导致其荧光猝灭;而Cu²⁺与草甘膦之间具有更强的配位能力,二者预先混合时,可阻断Cu²⁺与AuAgNCs@11-MUA之间的相互作用,体系的荧光处于“turn-on”状态,由此可实现对草甘膦的定量分析。在最优实验条件下,即体系pH=7.0、Cu²⁺和草甘膦孵育2 min,检测草甘膦的线性范围为0.025～1.0μg/mL,检出限(S/N=3)为8 ng/mL。以Cu²⁺和草甘膦为输入信号,构建了蕴涵分子逻辑门。本方法具有选择性好、响应速度快和灵敏度高等优点,可用于实际水样中草甘膦的检测。     

三芳胺类荧光探针合成及对化妆品中Hg2+的检测

基于汞离子促进硫代缩醛脱保护作用,设计合成了一种三芳胺类荧光探针N-(1,1′-联苯-4-基)-N-(4-(双(乙基硫代)-甲基)苯基)-9,9-二甲基-9H-芴-2-胺(简称L),并采用核磁共振、红外光谱及高分辨质谱对其结构表征。荧光发射光谱表明,在乙腈(ACN)/4-羟乙基哌嗪乙磺酸(HEPES)(V∶V=9∶1,HEPES 10mmol·L^-1,pH=7.4)缓冲溶液中,探针可实现对Hg²⁺的“turn-off”检测,检测过程具有响应时间短、离子选择性好、抗共存金属离子干扰性强等优点。在0～20μmol·L^-1范围内,Hg²⁺浓度与荧光强度呈现良好线性关系,探针对Hg²⁺检测极限低至1.57×10^-8 mol·L^-1,可实现Hg²⁺的痕量检测。将探针L应用于化妆品中Hg²⁺检测,加标回收率96.3%～101.7%,相对标准偏差0.52%～2.76%,准确度较高,具有良好的应用前景。     

离子印迹法制备对铜离子(Ⅱ)选择性吸附的碳基材料

通过钨离子印记方法,合成了对铜离子有高选择性吸附性能的碳基材料。 在四乙烯五胺(TEPA)、钨酸铵和葡萄糖摩尔比为1:1:5条件下,经水热法合成的碳基吸附材料能有效地吸附铜离子,对铜离子吸附的最佳pH=5。 在Cd²⁺、Co²⁺、Cu²⁺、Ni²⁺和Zn²⁺摩尔浓度相近体系中,离子印记碳基吸附材料对铜离子的吸附率高达97.2%,而对Cd²⁺、Co²⁺、Ni²⁺、Zn²⁺吸附率分别为20.1%、9.63%、20.3%、13.3%,表明这种离子印记碳基吸附材料对Cu²⁺具有非常优异的选择吸附能力。     

一种基于苯并噁唑类的可视化检测汞离子的荧光探针

设计合成了一种用于检测Hg²⁺的苯并噁唑类荧光探针4-(苯并[d]噁唑-2-基)-2-((二(2-(乙巯基)乙基)氨基)甲基)苯酚(ZY1), 用质谱、核磁氢谱和X射线单晶衍射等方法对其进行了结构表征, 并考察了其光谱性能. 研究结果表明, ZY1对Hg²⁺有较高的选择性和灵敏度, 它们之间的结合比为1:1, 共存离子及pH值(3.0～9.0)对其测定影响小. ZY1能够可视化检测Hg²⁺, 并在HeLa活细胞中实现了汞离子的成像, 这对检测生物体内的Hg²⁺将具有潜在的应用价值.     

用于汞离子检测和细胞成像的石墨相氮化碳量子点荧光探针

本文采用一步固相热解法，以尿素作为前体合成了石墨相氮化碳量子点(gCNQDs)．利用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FT-IR)等技术对g-CNQDs的粒径分布、元素组成、形貌结构和表面官能团进行表征．基于Hg²⁺淬灭g-CNQDs荧光的现象，构建可用于血样和尿样以及实际水样中Hg²⁺检测的荧光探针，在2.5～50.0μmol·L^-1范围内，Hg²⁺浓度与g-CNQDs相对荧光强度呈现良好的线性关系，检出限为1.5nmol·L^-1．在实际样品中检测Hg²⁺的加标回收率为97.17%～101.13%.g-CNQDs与Hg²⁺的相互作用机理主要为静态淬灭．该探针也被成功应用于肿瘤细胞成像．     

Computational studies of benzyl-substituted halonium ions

Density functional computations were carried out whose objectives were to quantify the interactions of chlorine and bromine with neighboring cationic centers in a series of 1-aryl-2-haloethyl cations. Analysis of structural changes and bonding interactions gave rise to linear correlations with σ⁺ values of the aryl substituents. Electron-donating groups diminished bridging and electron-withdrawing groups gave rise to stronger bridging.     

Developments in suppressor technology for inorganic ion analysis by ion chromatography using conductivity detection

A review is presented detailing the development and use of suppression devices for the conductimetric detection of inorganic ions by ion chromatography (IC). An overview of the general response equation for conductivity detection is also given. Topics of discussion include the role and function of suppressors, the development of early suppressors including packed column and membrane devices from 1975 to 1990 and the subsequent progression towards present day commercially available suppressors and recent innovations. Post-suppression devices for signal enhancement are also discussed.     

Selective recognition of Fe3+ and Cr3+ in aqueous medium via fluorescence quenching of graphene quantum dots

Graphene quantum dots (GQDs) have been prepared from graphene oxide (GO) and characterized by standard analytical techniques. The size of the prepared GQDs ranges from 2-10?nm. Aqueous dispersion of GQDs exhibited excitation-dependent emission behavior. Emission intensity of the aqueous dispersion found stable for the examined duration of about four months. GQDs exhibited selective recognition of Fe³⁺ and Cr³⁺ out of various common ions such as alkali, alkaline-earth and transition metal ions in aqueous medium through fluorescence quenching. The lower limit of detection of Fe³⁺ is 1?µM and that of Cr³⁺ is 4?µM.     

Efficient and Divergent Synthesis of α‐Halogenated Amides and Esters by Double Electrophilic Activation of Ynamides

An efficient and modular entry to α‐halogenated amides and esters is reported. This reaction is based on an underestimated double electrophilic activation of ynamides sequentially involving highly reactive activated keteniminium and iminium ions. Upon simple reaction with HCl and an electrophilic halogenation reagent in the presence of water or an alcohol, a broad range of ynamides can be transformed, in a highly divergent manner, to α‐halo amides and esters with high efficiency and under mild conditions.     

Electrochemical sensor for Cd2+ and Pb2+ detection based on nano-porous pseudo carbon paste electrode

An electrochemical sensor based on self-made nano-porous pseudo carbon paste electrode (nano-PPCPE) has been successfully developed, and used to detect Cd²⁺ and Pb²⁺. The experimental results showed that the electrochemical performance of nanoPPCPE is evidently better than both glassy carbon electrode (GCE) and pure carbon paste electrode (CPE). Then the prepared nano-PPCPE was applied to detect Cd²⁺ and Pb²⁺ in standard solution, the results showed that the electrodes can quantitatively detect trace Cd²⁺ and Pb²⁺, which has great significance in electrochemical analysis and detection. The linear ranges between the target ions concentration and the DPASV current were from 0.1–3.0 μmol/L, 0.05–4.0 μmol/L for Cd²⁺ and Pb²⁺, respectively. And the detection limits were 0.0780 μmol/L and 0.0292 μmol/L, respectively. Moreover, the preparation of the nano-PPCPE is cheap, simple and has important practical value.     

Transition‐Metal Carbodiimides as Molecular Negative Electrode Materials for Lithium‐ and Sodium‐Ion Batteries with Excellent Cycling Properties

We report evidence for the electrochemical activity of transition‐metal carbodiimides versus lithium and sodium. In particular, iron carbodiimide, FeNCN, can be efficiently used as negative electrode material for alkali‐metal‐ion batteries, similar to its oxide analogue FeO. Based on ⁵⁷Fe Mössbauer and infrared spectroscopy (IR) data, the electrochemical reaction mechanism can be explained by the reversible transformation of the Fe?NCN into Li/Na?NCN bonds during discharge and charge. These new electrode materials exhibit higher capacity compared to well‐established negative electrode references such as graphite or hard carbon. Contrary to its oxide analogue, iron carbodiimide does not require heavy treatments (such as nanoscale tailoring, sophisticated textures, or coating) to obtain long cycle life with current density as high as 9 A g^?1 for hundreds of charge–discharge cycles. Similar to the iron compound, several other transition‐metal carbodiimides M_x(NCN)_y with M=Mn, Cr, Zn can cycle successfully versus lithium and sodium. Their electrochemical activity and performance open the way to the design of a novel family of anode materials.     

Fluorescent Sensing Properties of Three Coordination Polymers Constructed by 3,5‐Di(2′,5‐dicarboxylphenyl)pyridine Ligand

Three Cd^II coordination polymers (CPs), named as {[Cd₂(DDPP)(DMF)(H₂O)] · DMF}_n ( 1 ), {[Cd₂(DDPP)(H₂O)₂] · DMA · H₂O}_n ( 2 ), [Cd(H₂DDPP)]_n ( 3 ), based on 3,5‐di(2′,5‐dicarboxylphenyl)pyridine) (H₄DDPP), were synthesized under solvothermal methods. Structural analysis indicates that the H₄DDPP ligand of 1 – 3 adopt (κ₁‐κ₁)‐(κ₁‐κ₁)‐(κ₁‐κ₂)‐(κ₁‐κ₁)‐μ₈, (κ₁‐κ₁)‐(κ₁‐κ₂)‐(κ₁‐κ₂)‐(κ₁‐κ₁)‐μ₁₀, and (κ₀‐κ₀)‐(κ₁‐κ₂)‐(κ₁‐κ₂)‐(κ₀‐κ₀)‐μ₆ coordination modes, respectively. CP 1 is a 2‐nodal (4,8)‐c alb ‐ 4 , 8 ‐ Pbcn network. CP 2 is a 3D 4,8‐c flu/fluorite network. CP 3 displays a 2D layer, which is further connected with hycrogen‐bonding interactions between layers to form supramolecular framework. Moreover, the fluorescent features of 1 – 3 were studied in aqueous systems and the values of detection limit (DL) are also calculated by 3σ/k_sv. The results reveal that 1 – 3 have good ability on probing Cr^VI/Fe^III ions.     

Specific adsorption of anions preceding the dissolution of CuO in acidic solution

The specific adsorption of sulfate and chloride ions on powdered CuO was studied by radiotracer techniques in acidified of 0.5 mol dm^–3 NaClO₄ supporting electrolyte. It was found that the pH and concentration dependence of the adsorption of labelled sulfates could be determined over a wide pH range (2.0≤pH≤7.0), despite the gradual dissolution of the copper oxide. No specific adsorption was found at pH≥7.0. It was postulated that the specific adsorption was preceded by the protonation of the CuO surface. No reliable relationships were found for labelled chlorides, owing to the relatively high desorption rate of the surface complexes formed in the sorption process. The apparent adsorbability of sulfate ions was significantly higher than that of the chloride ions, as shown by the results of competitive adsorption of the two species. This observation was in agreement with the postulated lower desorption rate of the surface complex formed with sulfates than that of species formed with chlorides. Electronic Publication     

The evaluation and use of properties of individual ions in slution

A critical examination is given of extra-thermodynamic methods for evaluation of properties of individual ions in solution. The ways in which such data may be applied, or are required in various problems concerning specific properties of electrolyte solutions and in the fields of kinetics, electrochemistry, colloid and interfacial chemistry, are outlined. Special attention is given to the problem of evaluation of individual ionic thermodynamic functions for the hydration of ions but, in some cases, corresponding data for nonaqueous solutions are available for discussion and are of interest in a comparative way. The reliability of the various methods is assessed and estimates of numerical values for various individual ionic functions are tabulated. The question of scales of individual ionic radii, on which some of the derived data depend, is also examined. The dependence of various properties for anions and for cations on ionic radius is discussed and data are plotted comparatively. It is shown that for most, but not all, properties, the values for anions are more sensitive to increasing ionic radius than are the values for cations. This behavior, as well as the exceptions, is of theoretical interest. The significance of ion-specific behavior at interfaces is considered and the importance of interactions between ions of like sign of charge is indicated.Presented at the Symposium on Electrolytes, University of Reading, September 13, 1977.     

聚苯胺及其复合物对重金属离子的高效吸附性能

基于国外最新文献,系统总结了近年来聚苯胺及其复合物的制备方法及其重金属离子吸附性能,重点分析了吸附性能特征,指出聚苯胺及其复合物具有吸附下限浓度低、达到吸附平衡快以及解吸附性能优异等特点.填充有聚苯胺颗粒的吸附柱在动态处理初始浓度为83 ng/L的汞离子溶液时,经一次吸附与解吸循环操作后,汞离子的富集倍数可达120倍.应用于冷原子吸收光谱的待测样品的浓缩与富集,可以将汞的测试下限拓展到0.05 ng/L.聚苯胺及其复合物在痕量重金属离子的高效富集与灵敏探测等方面展示了广阔的应用前景.