Ru(Ⅱ) Bipyridyl Complex and TiO2 Nanocomposite Based Biomolecule-free Photoelectrochemical Sensor for Highly Selective Determination of Ultra-trace Hg^2+ in Aqueous Systems

A biomolecule-free photoelectrochemical(PEC) probe(denoted as Ru-1) was designed, synthesized and coupled with TiO2 nanoparticles(NPs) for the highly sensitive and selective PEC detection of Hg^2+, a model analyte with hypertoxicity to both human health and ecosystem. The probe Ru-1 was designed with Ru(Ⅱ) bipyridyl complex as the chromophore, thiocyanate ligand as the recognition unit, and carboxylate group as the linkage site to connect Ru-1 to TiO2 nanoparticles. Under irradiation, Ru-1 shows strong affinity to TiO2 and good photophysical properties of strong visible light absorption, slow electron-hole(e-h^+) recombination, and fast photoelectron injection to TiO2 nanoparticles via the bridge of 4-(2,2-bipyridin)-4-yl-thiophene moiety. However, the specific coordination of Hg^2+ with Ru-1 via the thiol moiety in the thiocyanate enlarges the band gap of tlie complex and reduces the photocurrent significantly. The synergistic interaction between TiO2 nanoparticles and the Ru-1 complex led to a selective PEC sensing strategy for Hg^2+ detection. Detectable linear ranges from 10^-12 g/mL to 10^-7 g/mL and from 10^-7g/mL to 10^-3 g/mL were obtained without the interference from possibly co-existed metal ions. The good analytical performances indicate the chemical probe based biomolecule-free PEC platform may offer a new route for the detection of biologically and environmentally important small molecules.     

A ratiometric chemosensor for fluorescent determination of Hg based on a new porphyrin-quinoline dyad

Quinolin-8-ol p-[10′,15′,20′-triphenyl-5′-porphyrinyl]benzoate (1) was synthesized for the first time and developed as a ratiometric fluorescent chemosensor for recognition of Hg²⁺ ions in aqueous ethanol with high selectivity. The 1–Hg²⁺ complexation quenches the fluorescence of porphyrin at 646 nm and induces a new fluorescent enhancement at 603 nm. The fluorescent response of 1 towards Hg²⁺ seems to be caused by the binding of Hg²⁺ ion with the quinoline moiety, which was confirmed by the absorption spectra and ¹H NMR spectrum. The fluorescence response fits a Hill coefficient of 1 (1.0308), indicating the formation of a 1:1 stoichiometry for the 1–Hg²⁺ complex. The analytical performance characteristics of the chemosensor were investigated. The sensor shows a linear response toward Hg²⁺ in the concentration range of 3 × 10⁻⁷ to 2 × 10⁻⁵ M with a limit of detection of 2.2 × 10⁻⁸ M. Chemosensor 1 shows excellent selectivity to Hg²⁺ over transition metal cations except Cu²⁺, which quenches the fluorescence of 1 to some extent when it exists at equal molar concentration. Moreover, the chemosensor are pH-independent in 5.0–9.0 and show excellent selectivity for Hg²⁺ over transition metal cations.     

2-氨基-5-(对二甲氨基)苯基-1,3,4-噻二唑:Hg2+的选择性荧光传感分子

设计合成了结构简单的分子内电荷转移荧光传感分子1,3,4-噻二唑类衍生物(1), 实现了水-乙醇(体积比1∶9)混合溶剂中Hg2+的荧光猝灭型选择性灵敏传感, 荧光猝灭常数达5.5×105 mol-1·L, Hg2+线性响应范围为5.0×10-6～5.0×10-5mol/L. 基于等摩尔连续变化法、红外光谱和核磁滴定实验结果提出了传感分子1与Hg2+的1∶1型结合模式, 其中1-位S原子和2-位胺N原子为Hg2+配位原子; 结合光谱变化讨论了Hg2+结合显著增强分子内电荷转移的荧光猝灭机理.     

喹啉酮-香豆素类Hg2+比色荧光探针的合成及应用

设计合成了新型喹啉酮-香豆素类比色荧光探针7-二乙氨基-3-[3-(7-二乙氨基)香豆素基-3-氧代丙烯基]喹啉-2-酮(QCO), 用于检测水溶液中的Hg²⁺. 探针QCO对Hg²⁺表现出高选择性和强抗干扰性. 此外, Hg²⁺引起探针QCO溶液的颜色变化明显, 可裸眼识别. 比色法中, 吸收值比(A₅₀₀/A₃₈₀)与Hg²⁺浓度呈良好的线性关系, 其检出限为2.62×10^-8 mol/L. 荧光法中, 探针QCO对Hg²⁺的检出限为5.42×10^-8 mol/L. 经等摩尔变化( Job’s Plot)法、 质谱及红外光谱验证, 探针QCO与Hg²⁺形成络合比为1∶1(摩尔比)的络合物. 硅胶板实验和加标回收率实验结果表明, 探针QCO可用于检测实际水样中的Hg²⁺.     

A Highly Copper‐Selective Ratiometric Fluorescent Sensor Based on BODIPY

A new ratiometric fluorescent sensor ( 1 ) for Cu²⁺ based on 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) with di(2‐picolyl)amine (DPA) as ion recognition subunit has been synthesized and investigated in this work. The binding abilities of 1 towards different metal ions such as alkali and alkaline earth metal ions (Na⁺, K⁺, Mg²⁺, Ca²⁺) and other metal ions ( Ba²⁺, Zn²⁺, Cd²⁺, Fe²⁺, Fe³⁺, Pb²⁺, Ni²⁺, Co²⁺, Hg²⁺, Ag⁺) have been examined by UV‐vis and fluorescence spectroscopies. 1 displays high selectivity for Cu²⁺ among all test metal ions and a ～10‐fold fluorescence enhancement in I₅₈₂/I₅₅₈ upon excitation at visible excitation wavelength. The binding mode of 1 and Cu²⁺ is a 1:1 stoichiometry determined via studies of Job plot, the nonlinear fitting of the fluorometric titration and ESI mass.     

A colorimetric and fluorescent chemosensor for detection of Hg2+ using counterion exchange of cationic polydiacetylene

In this study, a colorimetric and fluorescent chemosensor for mercury ions (Hg²⁺) was developed. Cationic polydiacetylene (PDA) vesicles with a quaternary ammonium cation and iodide as a counterion show a blue-to-red color transition; the color change is accompanied by a fluorescence enhancement in selective response to Hg²⁺ ions because of a perturbation of the ene–yne conjugated backbone induced by counterion exchange. It allows for selective detection of Hg²⁺ with the naked eye and the sensor is used to determine Hg²⁺ concentrations in tap water samples.     

基于四丹磺酰胺杯[4]芳烃的汞离子荧光化学传感器

我们方便地合成了上沿修饰四丹磺酰胺基团的杯[4]芳烃衍生物1,发现该化合物在含50％水的乙腈中显示出对汞离子高选择性和灵敏性的识别作用,竞争实验表明多数金属离子对其检测干扰较小。机理研究结果表明荧光萃灭源于由丹磺酰胺基团到汞离子的光致电子转移过程。另外,通过研究1和1-Hg2+的荧光衰减实验,以及对比双丹磺酰胺杯[4]芳烃2和单丹磺酰胺杯[4]芳烃3对汞离子的识别作用,发现化合物1的四丹磺酰胺基团具有很好的预组织和协同作用。化合物1对汞离子的检测限为3.41×10-6 mol·L-1,这可以使1成为一个潜在的汞离子荧光化学传感器。     

A new highly sensitive and selective fluorescent probe for Hg2+ and its application in living cells

Abstract

A new coumarin-based probe (HgP) with two “S” groups was designed and synthesized The probe HgP exhibited a fast response time (<2?min) and high selectivity (DL, 2.2?×?10^?7?mol/L). Furthermore, its capability of biological application was stu died, and the results showed that it could be applied to recognize Hg²⁺ in living cells (HK2 cells).     

Azido chelating fiber: synthesis,characterization and adsorption performances towards Hg2+ and Pb2+ from water

Herein, we report the synthesis and adsorption property of a novel chelating fiber containing azido group. Firstly, the brominated fiber (PP‐St‐DVB‐Br) was obtained via the reaction of polypropylene‐(g)‐styrene‐divinylbenzene fiber (PP‐St‐DVB) with bromine in CH₂Cl₂ solution. Then, azido chelating fiber (PP‐St‐DVB‐N₃) was prepared by azidation of PP‐St‐DVB‐Br fiber. Its structure and properties were characterized by Fourier transform infrared, elemental analysis, thermogravimetric analysis, and chemical titration, respectively. The micromophology and functional group distribution in fibrous matrix were investigated by scanning electron microscopy‐energy dispersive spectroscopy. The results show that the chelating fiber has high functional group contents (2.11 mmol/g for PP‐St‐DVB‐N₃) and uniform distribution. Different from granulate chelating resin, the novel fibrous adsorbent possesses excellent adsorption ability for Hg(II) and Pb(II) ions (408.9 mg/g for Hg²⁺ and 334.4 mg/g for Pb²⁺), and the adsorption capacity of the fiber has no loss until five cycles. The novel absorbent material shows the potential application prospect in the treatment of heavy metal wastewater. Copyright © 2017 John Wiley & Sons, Ltd.     

A multifunctional aggregation-induced emission (AIE)-active fluorescent chemosensor for detection of Zn2+ and Hg2+

An aggregation-induced emission (AIE)-active fluorescent chemosensor based on a tetraphenylethene (TPE) unit has been successfully designed and synthesized. Interestingly, the luminogen could detect Zn²⁺ selectively in a THF solution with the detection limit of 1.24 × 10⁻⁶ mol L⁻¹. Meanwhile, the luminogen could also detect Hg²⁺ selectively in a THF-water mixture with the water content of 90%, and the detection limit was 2.55 × 10⁻⁹ mol L⁻¹. Furthermore, the solid-state mechanochromic fluorescence behavior of the luminogen was investigated systematically. Indeed, the AIE-active luminogen also exhibited reversible mechanofluorochromic phenomenon involving fluorescent color change from blue to green, and powder X-ray diffraction results indicated that the switchable morphology conversion between crystalline and amorphous states was responsible for this mechanochromism phenomenon.     

Novel Fluorescent Chemosensors Based on Tryptophan Unit for Cu2+ and Fe3+ in Aqueous Solution

We reported four fluorescent chemosensors containing tryptophan units. The fluorescence spectrum titration experiments suggest that chemosensors 1, 2, 3 and 4 are highly selective for Cu²⁺ and Fe³⁺ over Li⁺, Na⁺, K⁺, Co²⁺, Zn²⁺, Ni²⁺, Hg²⁺ and Cr³⁺ via forming complexes with Cu²⁺ or Fe³⁺, which is confirmed by dramatical quench of fluoreseence in aqueous solution at pH 7.4, thus making all the chemosensors suitable for Cu²⁺ and Fe³⁺ fluorescent sensors.     

A Fluorescent and Colorimetric Probe Based on Isatin-appended Rhodamine for the Detection of Hg2+

A new fluorescent probe for the detection of Hg²⁺ was designed and synthesized via attaching N-methylisatin to rhodamine B hydrazide through an imine linkage. In an ethanol-Tris buffer medium, the addition of Hg²⁺ caused a strong orange fluorescence and a visual color change from colorless to pink. Other coexisting metal ions did not interfere with the detection of Hg²⁺. The research on the detection of Hg²⁺ in natural water suggested the possibility of practical applications in environment monitoring. Based on ESI-MS analysis, the Hg²⁺-sensing mechanism was proposed.     

A Highly Sensitive Quinoline-Containing Rhodamine B Thiohydrazide Based Fluorescent Probe for Hg2+ in Aqueous Solution and Living Cells

Quinoline-appended rhodamine B thiohydrazide based fluorescent probe was designed and applied in fluorescent detections of mercury ions in both aqueous solution and living cells. The signal change of the probe is based on a specific metal ion induced reversible ring-opening mechanism of a rhodamine B thiohydrazide. The probe exhibits a dynamic response concentration range for Hg²⁺ from 1.0 × 10^?8 to 1.0 × 10^?5 M with a detection limit of 8.5 × 10^?9 M. The fluorescent probe is pH independent in medium condition and exhibits high selectivity over other common metal ions.     

基于温敏性有机/无机杂化纳米粒子的比率型Hg~(2+)荧光探针

基于有机/无机杂化纳米粒子制备了能够对汞离子(Hg~(2+))进行比率型检测的荧光探针.首先通过连续的可逆加成-断裂链转移(RAFT)聚合合成了两亲性嵌段聚合物,P(MPS-co-NBDAE)-b-P(NIPAM-co-Rh BHA).其疏水嵌段为带有三甲基硅氧烷侧基,并标记有荧光能量给体N-(7-硝基-2,1,3-苯并噁二唑)(NBD)基元的聚丙烯酸酯,P(MPS-co-NBDAE);亲水嵌段为共聚有潜在荧光能量受体罗丹明脲衍生物单体(Rh BHA)的温敏性聚(N-异丙基丙烯酰胺),P(NIPAM-co-Rh BHA).由该嵌段聚合物自组装形成的胶束在三乙胺催化作用下水解发生溶胶-凝胶化过程后,得到核交联的有机/无机杂化纳米粒子.在没有Hg~(2+)离子存在时,该杂化纳米粒子溶液只显示出NBD基元发射的绿光;而在有Hg~(2+)离子存在条件下,Hg~(2+)离子可诱导Rh BHA开环为具有荧光发射性能的Rh B基元.由于NBD与Rh B之间的荧光共振能量转移(FRET)效应,杂化纳米粒子溶液的颜色和荧光发射性能均会发生明显的变化,从而实现对水溶液中Hg~(2+)离子的高效选择性检测.而且,升高温度会导致纳米粒子壳层PNIPAM嵌段的塌缩,使NBD和Rh B基元间的空间距离缩短,可进一步提高检测效果.因此,基于该有机/无机杂化纳米粒子的检测体系可用来对Hg~(2+)离子进行高效选择性检测.     

A dual-function chemosensor based on coumarin for fluorescent turn-on recognition of Hg2+ and colorimetric detection of Cu2+ in aqueous media

A novel coumarin derivative CTT was synthesized via the condensation of 7-(N,N-diethylamino) coumarin-3-aldehyde with 5-amino-1,3,4-thiadiazole-2-thiol and its structure was characterized using infrared spectroscopy (IR), ¹H NMR, mass spectrometry (MS) techniques, and elemental analysis. The recognition properties of CTT with metal ions were investigated in CH₃CN–H₂O (v/v = 1/1) solution using UV–vis absorption and fluorescence emission spectrum method. The results showed that CTT could monitor Cu²⁺ and Hg²⁺ simultaneously as a dual-function chemosensor in CH₃CN–H₂O (v/v = 1/1). CTT could be used to detect Cu²⁺ colorimetrically; when using CTT, a color change from yellowish-brown to yellowish-green could be readily observed by the naked eye. CTT showed turn-on fluorescent recognition of Hg²⁺, the fluorescence enhancement was attributed to the inhibited C=N isomerization and the obstructed excited state intramolecular proton transfer (ESIPT) of CTT. The recognition mechanism of CTT for Cu²⁺ and Hg²⁺ was studied by experiments and theoretical calculations, respectively. Therefore, CTT has the ability to be a “single chemosensor for dual targets.”     

基于T-T碱基错配的荧光传感器特异性检测汞离子

在本文中,我们研制了一种基于T-T碱基错配特异性键合汞离子的荧光传感器用于汞离子的检测。该传感器由两条分别标记了荧光基团（F）和淬灭基团（Q）的DNA探针组成,并且含有两对用于结合汞离子的T-T错配碱基。当汞离子存在时,两条探针之间形成T-Hg2+-T结构,作用力增强,从而拉近了荧光基团与淬灭基团之间的距离,发生能量转移,使荧光信号在一定程度上被淬灭。在优化的条件下,我们使用该传感器对汞离子进行检测,动力学响应范围为50nM到1000nM,线性相关方程为y= 5281.13 - 1650.56 lg[Hg2+] ( R2 = 0.985),检测下限为79nM。此外,我们还考察了该传感器的选择性,当用其它干扰离子（浓度都为1.0µM）代替待测离子进行实验时,没有发生明显的荧光淬灭,说明该传感器具有较高的选择性。该传感器的构建为汞离子的检测提供了一条快速、简便的新途径。     

Equilibrium and Kinetic Aspects of Hg(II) Extraction from Natural Waters with Diphenylthiocarbazone

A diphenylthiocarbazone (dithizone) based liquid-liquid extraction method of general utility is proposed for small-scale Hg(II) extraction from natural waters. The quantitative aspects related to the extraction are studied in terms of distribution of mercury dithizonate in carbon tetrachloride-water system at 293 K (20±1°C). Various distribution constants related to the reagent and the complex formed are evaluated. The equilibrium and kinetic studies of extraction and complex formation are analytically based on atomic absorption and colorimetric methods. Local natural waters were subjected to the proposed method for Hg(II) removal. The method is found to be capable of removing above 98% mercury in a single-step extraction under the conditions evaluated in terms of matrix pH, equilibration time and amount of reagent.     

A Highly Selective Fluorescent Chemosensor for Cu2+

A new Zn²⁺ probe L2-Zn(L2=naphthofuran carbonylhydrazone derivant) was synthesized as a fluorescence chemosensor for Cu²⁺, by which Cu²⁺ ion could be detected with high selectivity and sensitivity in a wide pH range via a displacement “turn-off” signaling strategy. Whereas the coordination between Zn²⁺ and L2 resulted in a considerable enhancement of typical luminescence of a naphthalofuran group in complex L2-Zn, the addition of Cu²⁺ ion led to a dramatic decrease in the emission intensity of probe L2-Zn at about 503 nm(excitation at 423 nm). The competitive fluorescent experiments showed that other metal ions, such as Hg²⁺, Fe³⁺, Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺ and Mg²⁺ could not impact the detection of Cu²⁺. The detection limit of the novel probe L2-Zn for Cu²⁺ ion was as low as 2.3×10^-7 mol/L, which is far lower than the guideline value of 1.6×10^-5 mol/L of the United States Environmental Protection Agency.     

基于香豆素骨架的Hg2+荧光探针的研究进展

本文综述了近十年来以香豆素衍生物为荧光基团的Hg~(2+)探针的研究进展,并对该类探针的分子结构、设计原理及使用性能给出简要介绍,对探针应用过程中的灵敏度、选择性以及检测条件等方面进行了评述,最后展望了该类荧光探针的研究和发展方向。     

Comparison of Two Rhodamine-Polyamine Polystyrene Solid-phase Fluorescence Sensors for Hg(II) Detection Based on Theoretical Calculation

Two novel rhodamine-based polystyrene solid-phase fluorescence sensors PS-PA-I and PS-PA-II with different lengths of polyamines were synthesized for Hg(II) determination. The detection mechanism involving the Hg(II) chelation-induced spirocycle open of rhodamine was proposed with the aid of theoretical calculation. The stronger N-Hg bond and the longer polyamine chain in PS-PA-II led to a better selectivity, much higher and more quickly fluorescence response to Hg(II).