A highly selective fluorescent chemosensor for Pb2+

A new fluorescent sensor based on rhodamine B for Pb2+ was synthesized. The new fluorescent sensor showed an extreme selectivity for Pb2+ over other metal ions examined in acetonitrile. Upon the addition of Pb2+, an overall emission change of 100-fold was observed, and the selectivity was calculated to be 200 times that of Zn2+. The signal transduction occurs via of reversible CHEF (chelation-enhanced fluorescence) with this inherent quenching metal ion.     

Development and applications of fluorescent indicators for Mg2+ and Zn2+

In a study of the spectroscopic behavior of two Schiff base derivatives, salicylaldehyde salicylhydrazone (1) and salicylaldehyde benzoylhydrazone (2), Schiff base 1 has high selectivity for Zn(2+) ion not only in abiotic systems but also in living cells. The ion selectivity of 1 for Zn(2+) can be switched for Mg(2+) by swapping the solvent from ethanol-water to DMF (N,N-dimethylformamide)-water mixtures. Imine 2 is a good fluorescent probe for Zn(2+) in ethanol-water media. Many other ions tested, such as Li(+), Na(+), Al(3+), K(+), Ca(2+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Ag(+), Cd(2+), Sn(2+), Ba(2+), Hg(2+), and Pb(2+), failed to induce any spectral change in various solvents. The selectivity mechanism of 1 and 2 for metal ions is based on a combinational effect of proton transfer (ESPT), C═N isomerization, and chelation-enhanced fluorescence (CHEF). The coordination modes of the complexes were investigated.     

Fluorescence sensing and binding behavior of aminobenzenesulfonamidoquinolino-beta-cyclodextrin to Zn2+

A water-soluble fluorescent zinc sensor which binds strongly to Zn2+ (log K = 12.4) was successfully synthesized under physiological conditions. This sensor exhibits a good fluorescence response to Zn2+ over a wide pH range in water. Under the same conditions, several metal ions commonly present in a physiological environment, such as Na+, K+, Ca2+, Mg2+, Mn2+, Fe2+, and Co2+, showed little interference to the fluorescence response to Zn2+. [structure: see text]     

吡咯并[2,1,5-cd]中氮茚酰腙衍生物的合成及Cu2+荧光探针行为

设计合成了吡咯并[2,1,5-cd]中氮茚酰腙衍生物6. 测试了其紫外光谱和荧光光谱, 研究了其对铜离子的选择性识别作用. 结果表明, 化合物6作为铜离子荧光探针, 受常见离子干扰较小, 对于铜离子有着较高的选择性和较低的检出限.     

A ratiometric fluorescence probe for selective visual sensing of Zn2+

A simple ratiometric fluorescence probe based on vinylpyrrole end-capped bipyridine for the visual sensing of Zn2+ under aqueous physiological pH (6.8-7.4) is described. The fluorophores 3a-c showed strong emission around 537 nm in acetonitrile with a quantum yield of 0.4. In buffered (HEPES, pH 7.2) acetonitrile-water mixture (9:1 v/v), titration of transition metal salts to 3c showed strong quenching of the emission at 547 nm except in the case of Zn2+, which resulted in a red-shifted emission at 637 nm. Alkali and alkaline earth metal salts could not induce any considerable changes to the emission behavior of 3a-c. The binding of Zn2+ was highly selective in the presence of a variety of other metal ions. Though Cu2+ quenches the emission of 3c, in the presence of Zn2+, a red emission prevails, indicating the preference of 3c toward Zn2+. Job plot and Benesi-Hildebrand analysis revealed a 1:1 complexation between the probe and the metal ion. The selective visual sensing of Zn2+ with a red emission is ideally suited for the imaging of biological specimens.     

"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.     

表面活性剂增溶比率荧光Zn2+检测方法研究

合成了一种新的Zn2+荧光检测试剂8-(2-(十八氨基)乙酰氨基)喹啉(AQZ-18)。通过自发荧光的非离子表面活性剂OP-10增溶AQZ-18,获得了一个与Zn2+结合后在320 nm和505 nm分别有两个荧光发射峰的溶液体系。短波长荧光峰来自OP-10,荧光峰强度不随Zn2+浓度变化;长波长荧光峰来自AQZ-18,荧光峰强度随Zn2+浓度增加而增强。利用上述两个荧光峰强度随Zn2+浓度变化时的比值变化建立了一种新的比率荧光Zn2+检测方法。研究表明,Zn2+与AQZ-18形成1∶1型基态配合物,其表观结合常数为1.1×106L/mol。常见金属离子对Zn2+荧光检测无干扰,Zn2+浓度在0～1.1×10-5mol/L范围内与荧光强度变化的比值呈良好的线性关系,相关系数(r2)为0.996 2,检出限为55 nmol/L。该方法可用于水样中Zn2+的检测。     

1-乙酰基-3-(2-羟基-4,6-二甲氧基苯基)-5-苯基-2-吡唑啉的合成及锌离子探针的研究

设计合成了1-乙酰基-3-(2-羟基-4,6-二甲氧基苯基)-5-苯基-2-吡唑啉(4), 测试了其紫外光谱和荧光光谱, 研究了其对锌离子的选择性识别作用. 结果表明, 化合物4作为锌离子荧光探针, 受常见离子的干扰较小, 对于锌离子有着较高的选择性和较低的检出限.     

1-乙酰基-3-(2-羟基-4,6-二甲氧基苯基)-5-芳基-2-吡唑啉的合成及Cu2+荧光探针行为

设计合成了6个1-乙酰基-3-(2-羟基-4,6二甲氧基苯基)-5-芳基-2-吡唑啉化合物4a～4f.测试了它们的紫外光谱和荧光光谱,研究了其对铜离子的选择性识别作用.结果表明,化合物4f作为铜离子荧光探针,受常见离子干扰较小,对于铜离子有着较高的选择性和较低的检出限.     

New Hg2+ and Cu2+ selective chromo- and fluoroionophore based on a bichromophoric azine

[graph: see text] A new probe, 1,4-bis(1-pyrenyl)-2,3-diaza-1,3-butadiene, selectively senses Hg2+ and Cu2+ through two different channels: the yellow-deep-pink color change and the enhancement of the fluorescence with the red shift of the excimer emission, which can visually be discernible by a green fluorescence in the presence of Hg2+ and an orange fluorescence in the presence of Cu2+.     

Cyclam-methylbenzimidazole: a selective OFF-ON fluorescent sensor for zinc

The coordination properties and the photophysical response of a new cyclam fluorescent probe for Zn(II), [L1H: 1-(benzimidazol-2-ylmethyl]-1,4, 8,11-tetraazacyclotetradecane] toward Cu(II), Zn(II), and Cd(II) are reported. The stability constants of the corresponding complexes were determined by means of potentiometric measurements in aqueous solution. The fluorescence of L1H was quenched by the presence of Cu(II), and L1H behaves as an OFF-ON sensor for Zn(II) even in the presence of a wide range of biological divalent cations. Furthermore, on addition of successive amounts of Zn(II), the fluorescence emission of L1H increases linearly by a factor of 12. This can be correlated to the efficient Zn(II) binding of L1H and to the participation of all the amine functions in the metal coordination which prevents the photoinduced electron transfer (PET) effect and promotes a good chelation-enhanced fluorescence (CHEF) effect; this confers to the cyclam probe better sensing properties than the cyclen ionophore.     

基于氟硼二吡咯染料的汞离子荧光分子探针的合成与光谱性质

合成了一种中位-苯甲酸基取代的氟硼二吡咯类染料衍生物(1)并研究了它的金属离子传感性能。在甲醇溶液中,染料1显示出显著的对汞离子具有选择性的"开-关"型亲离子荧光团响应,而对其他一些代表性碱金属、碱土金属、过渡金属及重金属离子等都没有明显的荧光响应;同时染料1在对所检测的金属离子中,通过其溶液颜色的改变对汞离子显示出明显的选择性显色行为,以便实现对汞离子的"裸眼检测"。     

Detecting Hg2+ ions with an ICT fluorescent sensor molecule: remarkable emission spectra shift and unique selectivity

A fluorescent ratiometric Hg2+ ion sensor RMS, based on a coumarin platform coupled with a tetraamide receptor, is presented. This sensor, employing the ICT mechanism, could be used to specifically detect Hg2+ ions in a neutral buffered water solution with an approximately 100-nm blue shift in emission spectra.     

一种基于三苯胺类共轭聚合物荧光信号开启的汞离子检测方法

通过Suzuki反应合成出主链中含9,9-二(4-二苯胺基苯基)-3,6-芴的蓝光共轭聚合物—聚[2,7-(9,9-二辛基芴)-co-3,6-(9,9-二三苯胺基芴)] (36PFT).36PFT可特异地与I-相互作用,并淬灭36PFT的荧光.当I-的浓度为0.24 mmol/L时,36PFT的荧光淬灭程度可达95％,...     

基于蒽酰亚胺基团的新型Fe3+和Hg2+化学敏感器

含蒽酰亚胺基团的化合物N-(2-(6-氨基吡啶))-9-蒽酰亚胺(L¹)对Fe³⁺表现出灵敏的荧光增强响应.L¹的衍生物N,N-’(2,6-吡啶基)-二(9-蒽酰亚胺)(L²)对Hg²⁺在紫外-可见吸收光谱和荧光光谱上显示了良好的识别性.即使在其它金属阳离子存在下,L¹和L²分别对于Fe³⁺和Hg²⁺仍然表现出较好的选择性.     

Multisignaling optical-electrochemical sensor for Hg2+ based on a rhodamine derivative with a ferrocene unit

A new multisignaling sensor based on rhodamine B with a ferrocene substituent (1) has been synthesized and has been shown to display extreme selectivity for Hg2+ over other metal ions. Multisignaling changes are observed through UV/vis absorption, fluorescence emission, and electrochemical measurements. Furthermore, by means of confocal laser scanning microscopy experiments, it is demonstrated that 1 can be used as a fluorescent probe for monitoring Hg2+ in living cells.     

A calixarene based fluorescent Sr2+ and Ca2+ probe

A fluorescent probe, PyCalix, which has two pyrene moieties at the lower rim of a calix[4]arene fixed in the cone conformation was synthesized and its complexation behavior with alkali and alkaline earth cations was studied by fluorescence spectrometry. The compound showed intramolecular excimer emission at approximately 480 nm in the fluorescence spectra. Upon complexation with alkaline earth metal cations, a decrease of excimer emission was observed. The decrease of excimer emission was accompanied by an increase of monomer emission of pyrenes at 397 nm. The order of complexation constants of PyCalix with metal ions was Sr(+ approximately Ca2+ > Ba2+ > Mg2+ > K+ > Na+ > Cs+ for all reagents. PyCalix doped polyvinyl chloride (PVC) membrane was fabricated and our results showed that this membrane can be used for selective detection of Sr2+.     

Development of an iminocoumarin-based zinc sensor suitable for ratiometric fluorescence imaging of neuronal zinc

Ratiometric imaging is a technique to reduce artifacts by minimizing the influence of extraneous factors on the fluorescence of a sensor and is particularly useful for cellular imaging studies. Here we characterized the iminocoumarin fluorophore as a new scaffold for sensors for ratiometric imaging. The iminocoumarin 4 showed a high quantum yield in aqueous media on excitation in the visible wavelength region, while its coumarin analogue showed little fluorescence. We therefore developed a novel fluorescence probe, ZnIC, for ratiometric imaging of Zn2+, using iminocoumarin as a fluorophore and (ethylamino)dipicolylamine as a Zn2+ chelator. ZnIC exhibited almost the same fluorescence properties as 4, and the emission spectrum of this probe was red-shifted on addition of Zn2+ under physiological conditions. ZnIC is selective for Zn2+ over other biologically important metal ions, such as Ca2+ and Mg2+, and has high affinity for Zn2+. To confirm the suitability of ZnIC for biological applications, we employed it for the ratiometric detection of changes in intracellular Zn2+ in cultured cells and in rat hippocampal slices. The results indicate that iminocoumarin is a useful fluorophore for fluorescence microscopic imaging and that ZnIC should be useful for studies on the biological functions of Zn2+.     

Silole‐Infiltrated Photonic Crystal Films as Effective Fluorescence Sensor for Fe3+ and Hg2+

We develop a highly effective silole‐infiltrated photonic crystal (PC) film fluorescence sensor with high sensitivity, good selectivity and excellent reproducibility for Fe³⁺ and Hg²⁺ ions. Hexaphenylsilole (HPS) infiltrated PCs show amplified fluorescence due to the slow photon effect of PC because the emission wavelength of HPS is at the blue band edge of the selected PC’s stopband. The fluorescence can be quenched significantly by Fe³⁺/Hg²⁺ ions owing to electron transfer between HPS and metal ions. The amplified fluorescence enhances the sensitivity of detection, with a detection limit of 5 nM for Fe³⁺/Hg²⁺ ions. The sensor is negligibly responsive to other metal ions and can easily be reproduced by rinsing with pure water due to the special surface wettability of PC. As a result, a highly effective Fe³⁺/Hg²⁺ ions sensor based on HPS‐infiltrated PC film has been achieved, which will be important for effective and practical detection of heavy metal ions.     

Highly sensitive and selective chemosensor for Hg2+ based on the rhodamine fluorophore

A novel tren-based tripodal chemosensor 1 bearing a rhodamine and two tosyl groups was synthesized and its sensing behavior toward metal ions was investigated by UV/vis and fluorescence spectroscopies. Addition of a Hg2+ ion to a CH3CN solution of 1 gave a visual color change as well as significantly enhanced fluorescence, while other ions including Pb2+, Zn2+, Cu2+, Ca2+, Ba2+, Cd2+, Co2+, Mg2+, Ag+, Cs+, Li+, and Na+ induced no or much smaller color/spectral changes, which constituted a Hg2+-selective fluorescent chemosensor (OFF-ON).