Fluorogenic Hg2+-selective chemodosimeter derived from 8-hydroxyquinoline

[reaction: see text] A new thioamide derivative of 8-hydroxyquinoline-benzothiazole was prepared, and its fluorogenic chemodosimetric behaviors toward transition-metal ions were investigated. The thioamide derivative showed highly Hg2+-selective fluorescence enhancing properties (167-fold) in 30% aqueous acetonitrile solution. The selective and sensitive signaling behaviors were found to originate from the Hg2+ ion induced transformation of the very weak fluorescent thioamide derivative into a highly fluorescent amide analogue.     

Cyclams bearing diametrically disubstituted pyrenes as Cu2+- and Hg2+-selective fluoroionophores

New cyclam derivatives having diametrically disubstituted pyrene fluorophores were prepared and their fluoroionophoric properties toward transition metal ions were investigated. The compounds exhibited significant selectivity toward Hg2+ and Cu2+ ions in switching-off type responses in aqueous methanol or acetonitrile solution. Dipyrene-diamide derivative 3, having extra binding sites of the amide function, exhibited more pronounced chemosensing behavior toward Hg2+ and Cu2+ ions than its parent, dipyrene derivative 2. Detection limits for the analysis of Hg2+ and Cu2+ ions of dipyrene-diamide derivative 3 were 1.45x10(-6) and 1.30x10(-6) M, respectively. The diametrically disubstituted dipyrene-cyclam 2 may be utilized as a new starting platform for the design of other supramolecular fluorescent signaling systems having switching or chemosensing behaviors toward transition metal ions.     

Chemodosimetric Hg2+-selective signaling by mercuration of dichlorofluorescein derivatives

The chemodosimetric behavior of dichlorofluorescein derivatives toward Hg(2+) ions was investigated. Simple chemodosimetric systems showed selective and efficient signaling behaviors toward micromolar concentrations of Hg(2+) ions over other common interfering metal ions in an aqueous environment. The signaling mechanism is selective mercuration of the 4',5'-position of the xanthene moiety, which results in efficient chromogenic and fluorogenic signaling of Hg(2+) ions in aqueous environment.     

Hg2+-selective OFF-ON and Cu2+-selective ON-OFF type fluoroionophore based upon cyclam

[structure: see text]. A new cyclam derivative having two different fluorophores of pyrene and NBD subunits was prepared, and its Hg2+- and Cu2+-selective signaling behaviors were investigated. The detection limits for the analysis of Hg2+ and Cu2+ ions were found to be 7.9 x 10(-6) and 2.6 x 10(-7) M in aqueous acetonitrile solution (H2O-CH3CN = 10:90, v/v), respectively. The compound also exhibited a selective Hg2+/Cu2+-induced OFF-ON-OFF type of signaling pattern that can be utilized for the construction of functional supramolecular switching systems.     

"Turn-on" fluorescent sensor for Hg2+ via displacement approach

A new Cu2+ compound Cu- NB, (where H2 NB is bis(2-hydroxyl-naphthalene-carboxaldehyde) benzil dihydrazone) was synthesized as a highly selective fluorescence chemosensor for the detection of Hg2+ in aqueous media through a displacement "turn-on" signaling strategy. Whereas the coordination of Cu2+ resulted in a considerable quenching of the typical luminescence of the naphthol rings in Cu-NB, the addition of Hg2+ ion led to a dramatic increase in the emission intensity of Cu-NB at about 530 nm (excitation at 430 nm). The competitive fluorescent experiments showed that alkali, alkaline earth metal ions, the group 12 metals Zn2+, Cd2+, the first-row transition-metal ions such as Mn2+, Fe2+, Co2+, and Ni2+, as well as Pb2+ could not inhibit the Hg2+-binding fluorescent enhancement. It is postulated that the existence of Cu2+ in the luminescent probe Cu-NB could turn away the interferences of other metal cations from Hg2+ detection. The optical responses of the free ligand upon addition of Cu2+ ion, and of the Hg-H2NB compound upon the addition of Cu2+ were also investigated for comparisons.     

A rhodamine-based chemosensor that works in the biological system

A new rhodamine-based reversible chemosensor (L1 ) is reported, which could bind Hg2+ and Cu2+ in aqueous methanol solution with detectable change in color. Cu2+ and Hg2+ ions responded differently toward the fluorescence output signals on binding to L1.L1 could also be used as a selective probe for monitoring Hg2+ adsorbed on bacteria using an optical microscope.     

新型经由三氮唑连接的含芘基团的杯[4]芳烃：对锌离子的比率荧光识别及其在组合逻辑门中的应用

通过“click”反应合成了两个新的由三氮唑连接的含芘的杯[4]芳烃。 化合物1含有两个芘单元,对Zn2+表现出比率荧光响应,且对Cu2+, Hg2+ 和 Pb2+表现出选择性的荧光淬灭;而化合物2只含一个芘单元,对铜离子有显著的荧光淬灭,对汞离子有中等程度的荧光淬灭。利用化合物1对锌离子和铜离子不同的荧光响应,设计了INH和NOR逻辑门。     

胺化处理的纳米孔炭材料上汞(II)离子吸附性能

研究了纳米孔炭(NC)及乙二胺修饰的NC材料(NC-EDA)对水溶液中汞离子的吸附性能. 结果表明: NC材料对汞离子具有吸附能力; 经乙二胺修饰后, 材料的吸附性能显著提高; 并且NC-EDA材料经高温(873 K)处理后依然能够保持良好的吸附性能. 结合各种表征结果, 可以认为NC材料表面所富含的－COOH、－OH等基团有利于有机胺配体的引入, 使材料表面存在大量的碱性含氮物种. 这类碱性物种能够与汞离子发生较强的相互作用, 从而使材料表现出良好的汞离子吸附性能.     

α-呋喃甲醛缩对硝基苯胺对Hg2+的识别研究

设计合成了荧光传感分子α-呋喃甲醛缩对硝基苯胺(FFNA),通过红外(IR)光谱和核磁共振谱(1H NMR)表征了其结构.并应用荧光光谱研究其在水中对过渡金属离子的响应.结果表明,FFNA的荧光发射光谱对Hg2+表现出高的选择性响应,对Zn2+、Ni2+和Cd2+等金属离子响应则很弱;初步探讨了受体分子与Hg2+结合模式与荧光猝灭原因.     

Switching the recognition preference of rhodamine B spirolactam by replacing one atom: design of rhodamine B thiohydrazide for recognition of Hg(II) in aqueous solution

[STRUCTURE: SEE TEXT] A new chemosensor based on rhodamine B thiohydrazide is described. Chemosensor B was found to show a reversible dual chromo- and fluorogenic response toward Hg2+ in aqueous solution in a highly selective and sensitive manner. This was suggested to result from the coordination of Hg2+ at the N, S binding sites in B to open its spiro ring.     

双重印迹法制备汞离子印迹聚合物及其性能研究

采用双重印迹法,以N-3-(三甲氧基硅基)丙基乙二胺为功能单体,四乙氧基硅烷为交联剂,表面活性剂(十六烷基三甲基溴化铵)和Hg2+为模板,合成出Hg2+印迹聚合物.聚合物中的表面活性剂和Hg2+分别由乙醇萃取和HCl洗涤除去,利用平衡吸附法研究了聚合物的吸附性能和选择识别能力,且探讨了实验条件对印迹聚合物吸附性能的影响.结果表明,在竞争离子Cu2+(或Cd2+) 存在下,印迹聚合物具有较高的吸附能力和选择识别能力,最大相对选择系数k′>200,且可以循环使用.     

A Selective and Sensitive "Turn-on" Fluorescent Chemosensor for Recognition of Hg(2+) Ions in Water

Based upon highly selective and irreversible Hg(2+) -promoted deprotection of the dithioacetal reaction, a new water-soluble "turn-on" fluorescent chemosensor (1) was prepared and exhibited high selectivity and sensitivity towards the Hg(2+) ion over other heavy and transition-metal ions in pure water by transforming a weakly fluorescent precursor (colorless) to a highly fluorescent aldehyde (yellow-green; see figure) with a 155-fold increase in fluorescent intensity.     

New Hg2+-selective chromo- and fluoroionophore based upon 8-hydroxyquinoline

A new 8-hydroxyquinoline derivative having an appended boron-dipyrromethene function has been prepared, and its metal ion sensing properties were investigated. The designed compound exhibited pronounced Hg(2+)-selective on-off-type fluoroionophoric properties among the representative transition- and heavy-metal ions in aqueous dioxane solution. The fluorescence was efficiently quenched more than 98% with 5 equiv of Hg(2+) ions, and the detection limit was found to be 5 x 10(-)(6) M in a dioxane-water (1:3, v/v) solvent system. The ionophore also showed a selective chromogenic behavior toward Hg(2+) ions by changing the color of the solution from light amber to red, which can be detected with the naked eye.     

Tridentate lysine-based fluorescent sensor for Hg(II) in aqueous solution

A novel homoplastic podand fluorescent sensor based on flexible hydrophilic lysine was prepared. Lysine with two dansyl groups-appended at both ends supplied a possibility for a tridentate binding toward Hg(II) and finally resulted in a unique selectivity to Hg(II) over other transition-metal ions with a hypersensitivity (detection limit 2.0 nM) in neutral buffered aqueous solutions. Notably, the coordination of chloride ion to the complex of sensor-Hg(II) brought forth that the trend in the NMR chemical shift for hydrogen and carbon atoms of the sensor was contrary to the findings in the former reports, which shows upfield shifts for the hydrogens and the alkane carbons but downfield shifts for the dansyl carbons, respectively.     

A new Hg(2+)-selective chromoionophore based on calix[4]arenediazacrown ether

A new azophenol type chromogenic ionophore based on the p-tert-butylcalix[4]arenediazacrown ether was prepared: the ionophore exhibited a pronouncedly selective chromogenic behaviour toward Hg2+ ions among the surveyed guests of alkali, alkaline earth, transition and heavy metal ions in liquid-liquid extraction experiments.     

A rhodamine-based fluorescent and colorimetric chemodosimeter for the rapid detection of Hg2+ ions in aqueous media

A rhodamine-based fluorescent and colorimetric chemodosimeter for the rapid detection of Hg2+ ions in aqueous media was developed. The system, which utilizes an irreversible Hg2+-promoted oxadiazole forming reaction, responds instantaneously at room temperature in a 1:1 stoichiometric manner to the amount of Hg2+. The selectivity of this system for Hg2+ over other metal ions is remarkably high, and its sensitivity is below 2 ppb in aqueous solutions.     

汞离子的高灵敏度裸眼识别和荧光传感探针

设计合成了一种以耐尔蓝为母体的Hg2+光学探针分子1-苯甲酰-3-{2-[9-(乙氨基)-10-甲基-9H-苯并[α]苯酚-5-胺基]乙基}硫脲盐酸盐(NBET). 在pH=7.4的Tris-HCl缓冲液中, 探针分子最大吸收波长为640 nm, 此时溶液为淡蓝色; 加入汞离子可以诱导探针分子在640 nm处的吸收降低, 并在556 nm处产生新的吸收峰, 溶液变为浅紫色, 而其它金属离子的加入未引起显著变化, 基于此可对水溶液中的痕量Hg2+进行裸眼识别. 荧光光谱显示, 汞离子可以特异性地猝灭探针分子在660 nm处的荧光发射. 该探针分子的灵敏度、选择性及荧光量子产率高, 激发/发射波长长, 可以实现水溶液中0.005 μmol/L Hg2+的荧光检测.     

Synthesis, structure, photophysics, electrochemistry, and ion-binding studies of ruthenium(II) 1,10-phenanthroline complexes containing thia-, selena-, and aza-crown pendants

A series of ruthenium(II) diimine complexes containing thia-, selena- and aza-crowns derived from 1,10-phenanthroline have been synthesized and characterized, and their photophysics and electrochemistry were studied. Their interaction with metal ions was investigated by UV-vis, luminescence, and 1H NMR spectroscopy. The crystal structures of [Ru(bpy)2(L1)](PF6)2, [Ru(bpy)2(L2)](ClO4)2, [Ru(bpy)2(L3)](ClO4)2, and [Ru(bpy)2(L4)](ClO4)2 have been determined. The luminescence properties of [Ru(bpy)2(L1)](ClO4)2 were found to be sensitive and selective toward the presence of Hg2+ ions in an acetonitrile solution. The addition of alkaline-earth metal ions, Zn2+, Cd2+, and Hg2+ ions, to the solution of [Ru(bpy)2(L6)](ClO4)2 in acetonitrile gave rise to large changes in the UV-vis and emission spectra. The binding of metal ions to [Ru(bpy)2(L6)](ClO4)2 was found to cause a strong enhancement in the emission intensities of the complex, with high specificity toward Hg2+ ions.     

A highly selective and sensitive fluorescent chemosensor for Hg2+ in neutral buffer aqueous solution

A selective and sensitive fluorescent chemosensor for Hg2+, which was composed of two aminonaphthalimide fluorophores and a receptor of 2,6-bis(aminomethyl)pyridine, was synthesized through the reaction of 2,6-bis(chloromethyl)pyridine and N-[2-(2-hydroxyethoxy)ethyl]-4-piperazino-1,8-naphthalimide. The chemosensor showed an about 17-fold increase in fluorescence quantum yield upon addition of 1 equiv of Hg2+ in neutral buffer aqueous solution, and the other common metal ions did not notably disturb the detection of Hg2+.     

Preparation of a clay-modified carbon paste electrode based on 2-thiazoline-2-thiol-hexadecylammonium sorption for the sensitive determination of mercury.

A montmorillonite from Wyoming-USA was used to prepare an organo-clay complex, named 2-thiazoline-2-thiol-hexadecyltrimethylammonium-clay (TZT-HDTA-clay), for the purpose of the selective adsorption of the heavy metals ions and possible use as a chemically modified carbon paste electrode (CMCPE). Adsorption isotherms of Hg2+, Pb2+, Cd2+, Cu2+, and Zn2+ from aqueous solutions as a function of the pH were studied at 298 K. Conditions for quantitative retention and elution were established for each metal by batch and column methods. The organo-clay complex was very selective to Hg(II) in aqueous solution in which other metals and ions were also present. The accumulation voltammetry of Hg(II) was studied at a carbon paste electrode chemically modified with this material. The mercury response was evaluated with respect to the pH, electrode composition, preconcentration time, mercury concentration, "cleaning" solution, possible interferences and other variables. A carbon paste electrode modified by TZT-HDTA-clay showed two peaks: one cathodic peak at about 0.0 V and an anodic peak at 0.25 V, scanning the potential from -0.2 to 0.8 V (0.05 M KNO3 vs. Ag/AgCl). The anodic peak at 0.25 V presents excellent selectivity for Hg(II) ions in the presence of foreign ions. The detection limit was estimated as 0.1 microg L(-1). The precision of determination was satisfactory for the respective concentration level.