Synthesis of a di(2-picolyl)amino-β-diketone dual-functional ligand that can coordinate to europium(III) for responding to copper(II) and sulfide ions

Lanthanide complex-based luminescent probes/chemosensors have shown great utilities in various biological and environmental assays with time-resolved detection mode to eliminate background noises. In this work, by conjugating di(2-picolyl)amine (DPA) with a tetradentate β-diketone 1,2-bis[4'- (1",1",1",2",2"-pentafluoro-3",5"-pentanedion-5"-yl)benzyl]-4-chlorosulfo-benzene (BPPBCB), a novel dual-functional ligand that can coordinate to Eu³⁺ for responding to Cu²⁺ and S^2- ions in aqueous media, DPA-BPPBCB, has been designed and synthesized. The β-diketone moiety of DPA-BPPBCB can form a strongly luminescent complex with Eu³⁺. Upon reaction with Cu²⁺, accompanied by the formation of heterobimetallic complex Cu²⁺-DPA-BPPBCB-Eu³⁺, the Eu³⁺ luminescence was quenched. While in the presence of S^2-, owing to the high affinity of S^2- to Cu²⁺, stable CuS was formed, which resulted in the release of Cu²⁺ from Cu²⁺-DPA-BPPBCB-Eu³⁺, to restore the luminescence of the Eu³⁺ complex. This unique “on-off-on” luminescence response of the Eu³⁺ complex enabled Cu²⁺ and S^2- ions in aqueous media to be detected with time-resolved luminescence detection mode.     

铜离子与SALI3-2蛋白的相互作用

用1/2 MS固体培养基培养拟南芥幼苗, 研究了CuCl₂对转Sali3-2基因植株生长的影响, 发现转基因植株Sali3-2的表达可提高其耐受Cu²⁺胁迫的能力. 进一步克隆Sali3-2基因, 表达并纯化了缺失信号肽的 SALI3-2 蛋白. 利用固定金属离子亲和色谱(IMAC)分析发现, Cu²⁺ 能够与 SALI3-2 蛋白结合. 通过荧光光谱及圆二色光谱(CD)进一步研究了Cu²⁺ 与 SALI3-2 蛋白间的键合机理. 结果表明, Cu²⁺ 可引起SALI3-2 蛋白内源性荧光猝灭, 其猝灭机制为静态猝灭; Cu²⁺ 与SALI3-2 蛋白的结合常数为8.89×10⁶, 结合位点数为1.6. CD分析显示, Cu²⁺ 与SALI3-2 蛋白的结合未使SALI3-2 蛋白二级结构发生明显改变. 由此推测, 在高浓度铜离子胁迫下, SALI3-2蛋白通过结合一定数量的Cu²⁺使蛋白的构象发生改变, 这可能是SALI3-2蛋白的表达使植物耐受Cu²⁺胁迫能力提高的分子机制之一.     

Fluorescent peptide sensor for the selective detection of Cu

A new fluorescent peptidyl chemosensor for Cu²⁺ ions with fluorescence resonance energy transfer (FRET) capabilities has been synthesized via Fmoc solid-phase peptide synthesis. The metal chelating unit, which is flanked by the fluorophores tryptophan (donor) and dansyl chloride (acceptor), consists of the amino acids glycine and aspartic acid (Gly-Gly-Asp-Gly-Gly-Asp-Gly-Gly-Asp-Gly-Gly-Asp-Gly-Gly). Coordination of the Cu²⁺ ions to the metal chelating unit results in fluorescent quenching of both the donor and acceptor fluorophores. Although it was determined that Cu²⁺ binding causes no change in FRET efficiency, emission and Cu²⁺-induced quenching of the acceptor dye can be used to monitor the concentration of the copper ions, with a detection limit of 32 μg L⁻¹. The sensor also demonstrated sensitivity, reversibility and selectivity towards Cu²⁺ in a transition metal matrix at pH 7.0.     

11-Mercaptoundecanoic acid functionalized gold nanoclusters as fluorescent probes for the sensitive detection of Cu2+ and Fe3+ ions

Metal ions are physiologically essential,but excessive metal ions may cause severe risk to plants and animals.Here,we prepared gold nanoclusters(Au NCs) protected by 11-mercaptoundecanoic acid(11-MUA),which have excellent fluorescence properties for the detection of metal ions.The results showed that the copper ions(Cu~(2+)) and iron ions(Fe~(3+)) in the solution have obvious quenching effect on the fluorescence intensity of Au NCs.The detection range of Fe~(3+) was 0.8–4.5 mmol/L(R~2= 0.992) and 4.5–11.0 mmol/L(R~2= 0.997).And Cu~(2+) has a lower linear range(0.1–1.0 mmol/L,R2= 0.993).When EDTA was added into the reaction system,it was observed that the quenching effect of Cu~(2+) and Fe~(3+)on Au NCs showed different phenomenon.Then,the effect of metal ions on the fluorescence of Au NCs was investigated.The selective detection of Cu~(2+) was achieved by EDTA masking of Fe~(3+).In addition,we realized the metal ions detection application of Au NCs in the serum     

Highly sensitive and selective optical chemosensor for determination of Cu2+ in aqueous solution

A highly selective and sensitive rhodamine-based colorimetric chemosensor (1) for quantification of divalent copper in aqueous solution has been investigated in this work. It was designed using salicylaldehyde hydrazone and rhodamine 6G as copper-chelating and signal-reporting groups, respectively. In environmentally friendly media (50% (v/v) water/ethanol and 10 mM NaAc–HAc neutral buffer (pH 7.0)), the sensor exhibited selective absorbance enhancement to Cu²⁺ over other metal ions at 529 nm, with a dynamic working range of 0.05–5.00 μM and a detection limit of 10 nM Cu²⁺, respectively. To achieve fluorometric determination of Cu²⁺, the Cu²⁺-induced absorbance enhancement of 1 was efficiently converted to fluorescence quenching by fluorescence inner filter effects using rhodamine B (RB) as a fluorophore. The selectivity and sensitivity of fluorescence analysis were similar to those of absorptiometric measurement. Both absorptiometric and fluorometric methods were successfully applied to the detection of Cu²⁺ in three water samples.     

荧光素衍生物水杨醛荧光素腙的合成及对铜(Ⅱ)离子的检测

以荧光素酰肼与5-溴水杨醛反应合成了一种新型荧光素衍生物5-溴水杨醛荧光素腙(BSFH),采用红外、核磁、质谱、元素分析等技术手段对其进行了表征。 通过吸收光谱考察了在水溶液中BSFH对常见金属离子的选择性响应,发现BSFH在可见光区几乎无吸收,当加入常见金属离子时,吸收光谱上除了Cu²⁺之外的其它金属离子在496 nm处出现非常弱的吸收,而当Cu²⁺存在时,可以裸眼看到溶液颜色迅速从无色变为黄色,吸收光谱上在496 nm处出现了相对很强的吸收峰,并且随着Cu²⁺浓度的增加溶液的吸收强度不断增强,说明在水溶液中BSFH对Cu²⁺有很好的选择性。 实验结果表明,该化合物与Cu²⁺的化学计量比为1:1,Cu²⁺浓度线性范围为0.30~10 μmol/L,许多常见的金属离子不干扰Cu²⁺的测定,检测限为0.30 μmol/L,说明在水溶液中BSFH对铜离子具有很高的灵敏度。 据此,BSFH可以简单、快速、灵敏地在水溶液中识别和检测低浓度的铜离子。     

Anthracene derivatives bearing sulfur atoms or selenium atoms as fluorescent chemosensors for Cu and Hg: different selectivity induced from ligand immobilization onto anthracene

Two new selenium containing anthracene derivatives and two new sulfur containing anthracene derivatives were synthesized as fluorescent chemosensors for Hg²⁺ and Cu²⁺. Compound 1 displayed a highly selective chelation enhanced fluorescence quenching (CHEQ) effect only with Cu²⁺, on the other hand, compounds 3 and 4 displayed highly selective chelation enhanced fluorescence (CHEF) effects only with Hg²⁺ among the metal ions examined.     

A naphthalimide–calixarene as a two-faced and highly selective fluorescent chemosensor for Cu or F

A new naphthalimide–calix[4]arene was synthesized as a two-faced and highly selective fluorescent chemosensor for Cu²⁺ or F⁻. This chemosensor displayed a selective fluorescence quenching effect only with Cu²⁺ among the various metal ions. On the other hand, among the various anions, the title chemosensor displayed a selective fluorescence quenching effect only with F⁻. The binding mode with F⁻ was further investigated using fluorescence changes and ¹H NMR experiments.     

The synthesis and study of the fluorescent probe for sensing Cu2＋ based on a novel coumarin Schiff-base

A novel, fluorescent probe was synthesized from 2,4-dihydroxybenzaldehyde and 8-hydroxyquinoline for sensing Cu2+by the naked eye. The structure was confirmed by IR, MS,1H NMR,13 C NMR and the spectral properties of the probe were investigated. It exhibited strong fluorescence responses toward Cu2+and high selectivity over other metal ions. The binding constant between the probe and Cu2+was calculated using Benesi–Hildebrand equation.     

Aggregation-induced emission enhancement of yellow photoluminescent carbon dots for highly selective detection of environmental and intracellular copper(II) ions

Photoluminescent (PL) carbon nanodots (CDs) are prepared through a simple one-step hydrothermal treatment of o-phenylendiamine (OPD), and the as-prepared OPD-CDs show yellow PL emission under the ultraviolet excitation, which can be further enhanced by Cu²⁺ ions owing to Cu²⁺ ions induced aggregation of OPD-CDs through the coordination of Cu²⁺ with amino groups on the surface of OPD-CDs.     

Highly Sensitive and Selective Chemosensor for Cu2+ Based on a Schiff Base

A new chemosensor based on a Schiff base has been designed and synthesized. Its sensing behavior toward various metal ions was investigated by fluorescence and UV-Vis spectroscopic methods. The fluorescence of the sensor was quenched and the color rapidly changed from canary yellow to brown after the addition of Cu²⁺, while no changes occurred after the addition of other metal ions, which contributes to the detection of Cu²⁺ with naked eyes. The fluorescence quantum yield of the ligand was calculated to be 0.52. The corresponding detection limit of Cu²⁺ was 5.721×10^-7 mol/L, and the 1:1 binding mode of the sensor with Cu²⁺ was revealed by Job's plot.     

低温水相合成巯基化聚乙烯醇/CdS量子点纳米复合物及用于测定环境水样中痕量Cu~(2+)

采用水相合成法,在低温N2气保护条件下,以巯基化聚乙烯醇(PVA)为基体材料合成一种环境友好型PVA/CdS量子点纳米复合物,并通过红外光谱(IR)、X射线粉末衍射(XRD)、透射电子显微镜(TEM)、热重(TG)、荧光光谱(PL)和紫外可见光谱(UV-Vis)等技术手段对复合物进行结构表征和光学性能研究。测试结果表明,复合物中CdS量子点为立方晶型结构,形状为球形,粒径小于5nm,具有很好的稳定性、分散性及发光性质。此外,Cu~(2+)对PVA/CdS水溶液荧光具有良好的猝灭作用,其荧光猝灭程度与Cu~(2+)浓度在1~1000nmol/L范围内呈良好的线性关系,线性相关系数为0.9923,方法检出限为0.12nmol/L。该纳米复合物荧光分析方法简便快速、灵敏度高、检出限低,已应用于实际黄河水样中痕量Cu~(2+)的分析与检测。     

基于菲并咪唑的ON⁃OFF⁃ON双比色荧光探针及细胞成像

设计合成了对称型菲并咪唑荧光探针PIP-ph-PIP, 并对其结构进行了表征和确认. 随着探针溶液中水体积分数的增加, 探针的聚集程度逐渐增加, 荧光强度先增强后猝灭. 荧光光谱测试结果表明, 在水相体系中探针PIP-ph-PIP能以ON-OFF-ON的方式分别对Ag⁺和SCN^-, Cu²⁺和PO³₄ ^-进行连续识别, 且连续识别效果可通过裸眼比色观察, 其中对Ag⁺识别具有超低检出限(6.1 nmol/L). 结果表明, 探针PIP-ph-PIP可应用于活体HeLa细胞中Ag⁺和Cu²⁺的定性分析及实际水样中Ag⁺和Cu²⁺的定量检测.     

N,N-二甲基吡啶苯甲醛缩对二甲氨基苯甲酰腙的合成及对Cu2+的选择性识别

设计合成了可用于识别铜离子的化合物N,N-二甲基吡啶苯甲醛缩对二甲氨基苯甲酰腙(1), 通过¹H NMR, ¹³C NMR和MS等对其结构进行了表征; 采用荧光光谱和吸收光谱法研究了化合物1与金属离子间的相互作用. 结果表明, 化合物1对Cu²⁺ 呈现良好的选择性, Cu²⁺ 的加入使化合物1的荧光强度增强12.5倍, 加入其它金属离子如Fe³⁺, Zn²⁺, Pb²⁺, Hg²⁺, Cd²⁺, Co²⁺, Ni²⁺, Li⁺, K⁺, Ca²⁺, Mg²⁺ 和 Ag⁺, 仅引起化合物1荧光强度的微降. 采用双倒数线性回归拟合法计算可知, 化合物1与Cu²⁺ 形成了1: 1型强发光配合物, 结合常数为2.0×10⁷ L/mol.     

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.     

A highly selective chemosensor for copper ion based on ICT fluorescence

Simple structural compounds 1 to 3 were synthesized.The presence of Cu²⁺ resulted in the fluorescence and absorption spectra change of 1 and 2,which indicated that 1 and 2 showed a highly selective response to Cu²⁺ over other metal ions.However,3 showed no selectivity for metal ions,which means that the compound could bind with several metal ions,such as,Ni²⁺,Zn²⁺,Cd²⁺.Hg²⁺, Pb²⁺,Fe³⁺,Mg²⁺,Ca²⁺,and Co²⁺,except Cu²⁺ and Ag⁺.The different spectral responses were attributed to the difference in binding sites for 1 and 3.     

Modification of 4-(2-pyridylazo)-resorcinol postcolumn reagent selectivity through competitive equilibria with chelating ligands

Aminopolycar☐ylate ligands were added to the 4-(2-pyridylazo)-resorcinol (PAR) postcolumn reagent to alter the reagent selectivity towards transition metals. Addition of ethylenediaminetetraacetic acid (EDTA) completely suppressed the reaction between PAR and the metal ions. Addition of 0.1 mM nitrilotriacetic acid (NTA) to 1 mM PAR lowered the response to specific transition metal ions, but completely suppressed the PAR response to the lanthanides. Increasing the NTA concentration to 8 mM resulted in complete suppression of the PAR response to all metal ions except Cu²⁺ and Co²⁺ for which the detection limits were 3 and 1 ng, respectively. The observed selectivity results from the slow rate of conversion of metal ions from the M(NTA)₂⁴⁻ form to M(PAR)₂.     

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 new rhodamine-based fluorescent chemosensor for mercury in aqueous media

A new fluorescent ‘‘on–off' chemosensor for Hg2+initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2+over other commonly coexistent metal ions in aqueous media. Upon the addition of Hg2+, the spirocyclic ring of probe is opened and a significant enhancement of visible color and fluorescence in the range of 500–600 nm is observed. The colorimetric and fluorescent response to Hg2+can be conveniently detected by the naked eye, which provides a facile method for visual detection of Hg2+. From the molecular structure and spectral results of 1, an irreversible, hydrolysis, desulfurization reaction mechanism is proposed.     

Synthesis and fluorescence behaviour of crown and azacrown ethers carrying the dansyl fluorophore as a pendant in acetonitrile solution

The influence of Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Al³⁺ ions on the spectroscopic properties of the dansyl group covalently linked to crown ether or diazacrown ethers was investigated by means of absorption and emission spectrophotometry. Interaction of the alkali metal ions with all fluoroionophores studied is weak, while alkaline earth metal ions interact strongly causing about 50% quenching of dansyl fluorescence of A21C5-Dns and A₂18C6-Dns. The Cu²⁺, Pb²⁺ and Al³⁺ cations interact very strongly with dansyl chromophore regardless the crown ether type, causing a major change in absorption spectrum of the chromophore and forming non-fluorescent complexes. The Co²⁺, Ni²⁺, Zn², Mg²⁺ and Ag⁺ cations interact moderately with all fluoroionophores studied causing about 20% of fluorescence quenching of dansyl, except for a strong dansyl fluorescence quenching of 15C5-Dns by Co²⁺ ion. The quenching efficiency of didansylated fluoroionophores by the alkali metal ions and alkaline earth metal ions is weaker than monodansylated ones.