A naphthalimide-rhodamine ratiometric fluorescent probe for Hg based on fluorescence resonance energy transfer

On the basis of fluorescent resonance energy transfer from 1,8-naphthalimide to rhodamine B, a new fluorophore dyads (4) containing rhodamine B and a naphthalimide moiety was synthesized as a ratiometric fluorescent probe for detecting Hg²⁺ with a broad pH range 5.7-11.0. The selective fluorescence response of 4 to Hg²⁺ is due to the Hg²⁺-promoted desulfurization of the thiocarbonyl moiety, leading to the ring-opening of rhodamine B moiety of 4. When 4 was employed at 0.1 μM with the slit size being 20 nm/20 nm, a low level of Hg²⁺ (up to 3 × 10⁻⁸ M) can be detected using the system.     

用于半胱氨酸检测的比率荧光探针的合成与应用

合成了一个衍生于吡咯并吡咯二酮的用于半胱氨酸(Cys)检测的比率荧光探针,用核磁共振谱和质谱鉴定了其结构。探针与Cys作用后荧光发射最大波长由576 nm蓝移至536 nm,荧光颜色由黄色变为绿色,可裸眼直观识别。并且该探针可以专一性地识别Cys而不受其他氨基酸的影响。当Cys溶液浓度在0~300μmol/L内变化时,该探针荧光变化F536/F576符合线性关系(R=0.997),可以实现其定量检测。     

A novel coumarin‐based fluorescent probe for selective detection of cysteine over homocysteine

A coumarin‐based fluorescent probe containing both acrylate moiety and an allyl substituent was developed for distinguishing cysteine from homocysteine. The maximum absorption wavelength of the probe showed a bathochromic shift upon addition of cysteine and the colour changed from colourless to yellow. The maximum fluorescence emission at 462 nm of the probe was dramatically enhanced upon addition of cysteine in aqueous solution. In HEPES buffer (pH = 7.4, EtOH/H₂O = 9:1, v/v), both of the fluorescence emission bands of the probe at ca. 390 and 462 nm were intensely enhanced upon the addition of cysteine, while other amino acids, namely, homocysteine, asparaginic acid, methionine, glycine, phenylalaninase, valine, tryptophan, serine, glutamic acid and glutathione, did not cause a remarkable change. The probe can be used for selectively colorimetric and ratiometric fluorescent detection of cysteine over homocysteine and other common amino acids in both organic media and aqueous solution. The concentration of cysteine can be estimated by titration of the probe in aqueous solution, and the detection limit of the probe towards cysteine was 2 μmol/L.     

一种基于半菁染料的双重传感高选择性氰离子探针

通过7-二甲氨基香豆素-3-醛和碘化1,2-二甲基吡啶季盐的缩合反应合成了一种半菁染料。在纯水体系中,半菁染料以吸收波长蓝移和荧光淬灭双重传感高选择性地识别氰离子。双重传感效应归因于氰离子对半菁染料的麦克尔体系的亲核加成引起的共轭链的断裂,中断了香豆素和吡啶季盐结构单元间的分子内电荷转移。     

A highly selective chemosensor for Cu and Al in two different ways based on Salicylaldehyde Schiff

A novel, easily available colorimetric and fluorescent double-sensor 1 based on Salicylaldehyde bis-Schiff has been investigated in this work. The sensor exhibits highly selective and sensitive recognition toward Cu²⁺ in aqueous solution via a naked eye colour change from colourless to yellow and toward Al³⁺ via a significant fluorescent enhancement in ethanol over a wide range of tested metal ions. This represents the first reported Salicylaldehyde Schiff-based sensor capable of detecting both Cu²⁺ and Al³⁺ using two different modes.     

A NBD-based highly sensitive and selective colorimetric chemosensor for Ni2 + and Cu2 +

A new colorimetric chemosensor 1, containing the 7-nitrobenzo-2-oxo-1,3-diazolyl (NBD) moiety and the phenol one connected through Schiff-base linkage, has been synthesized. Sensor 1 showed remarkable color changes from pink to orange and pale brown, respectively, upon selective binding to Ni^2 + and Cu^2 + that can be identified by the naked-eye. The binding modes of sensor 1 to Ni^2 + and Cu^2 + were determined to be 1:1 stoichiometries using a Job plot and ESI-mass analysis. The sensor 1 showed high sensitivity toward Ni^2 + and Cu^2 + with the detection limits of 0.48 μM and 0.26 μM, respectively. The recognition properties of the sensor 1 toward Ni^2 + and Cu^2 + were explained by using photophysical experiments and theoretical calculations. Practically, sensor 1 functioned as a visible test strip for Ni^2 + and Cu^2 +.     

A highly selective fluorescent probe for real-time imaging of UDP-glucuronosyltransferase 1A8 in living cells and tissues

Uridine diphosphate(UDP)-glucuronosyltransferases(UGTs)are enzymes involved in the biotransformation of important endogenous compounds such as steroids,bile acids,and hormones as well as exogenous substances including drugs,environmental toxicants,and carcinogens.Here,a novel fluorescent probe BDMP was developed based on boron-dipyrromethene(BODIPY)with high sensitivity for the detection of UGT1A8.The glucuronidation of BDMP not only exhibited a redemission wavelength(lex/lem=500/580 nm),but also displayed an excellent UGT1A8-dependent fluorescence signal with a good linear relationship with UGT1A8 concentration.Based on this perfect biocompatibility and cell permeability,BDMP was successfully used to image endogenous UGT1A8 in human cancer cell lines(LoVo and HCT15)in real time.In addition,BDMP could also be used to visualize UGT1A8 in tumor tissues.These results suggested that BDMP is a promising molecular tool for the investigation of UGT1A8-mediated physiological function in humans.     

An unusual emissive and colorimetric copper (II) detection by a selective probe based on a pseudo-crown cysteine dye: Solution and gas phase studies

An off-on-off emissive and colorimetric probe L, based on a Pseudo-Crown cysteine dye was designed for Copper (II). Compound L was studied in solution and in gas-phase (MALDI-MS) over alkaline, alkaline, earth-alkaline and transition metal ions (Li⁺, Na⁺, K⁺, Ca^2 +, Mg^2 +, Zn^2 +, Cu^2 +, Co^2 +, Ni^2 +, Pb^2 +, and Hg^2 +) in organic media. The recognition of Cu^2 + by L lead to red/dark red colored complexes, one emissive L₂Cu and another LCu, less emissive. In regards to fluorescent quantum yield in both cases an increase respective to L was visualized (2 fold for LCu and 7 fold for L₂Cu). The paramagnetic nature of both complexes was proved by the synthesis of both complex species, as well as, through ¹H NMR and FTIR. Compound L demonstrate to be able to detect and quantify the minimal amounts of 1.3 μM/3.3 μM of Cu^2 +.     

A colorimetric method for the molecular weight determination of polyethylene glycol using gold nanoparticles

A gold nanoparticle (AuNP)-based colorimetric method was developed for the molecular weight (MW) determination of polyethylene glycol (PEG), a commonly used hydrophilic polymer. Addition of a salt solution to PEG-coated AuNP solutions helps in screening the electrostatic repulsion between nanoparticles and generating a color change of the solutions from wine red to blue in 10 min in accordance with the MW of PEG, which illustrates the different stability degrees (SDs) of the AuNPs. The SDs are calculated by the absorbance ratios of the stable to the aggregated AuNPs in the solution. The root mean square end-to-end length (〈h²〉^1/2) of PEG molecules shows a linear fit to the SDs of the PEG-coated AuNPs in a range of 1.938 ± 0.156 to 10.151 ± 0.176 nm. According to the Derjaguin-Landau-Verwey-Overbeek theory, the reason for this linear relationship is that the thickness of the PEG adlayer is roughly equivalent to the 〈h²〉^1/2 of the PEG molecules in solution, which determines the SDs of the AuNPs. Subsequently, the MW of the PEG can be obtained from its 〈h²〉^1/2 using a mathematical relationship between 〈h²〉^1/2 and MW of PEG molecule. Applying this approach, we determined the 〈h²〉^1/2 and the MW of four PEG samples according to their absorbance values from the ordinary ultraviolet–visible spectrophotometric measurements. Therefore, the MW of PEG can be distinguished straightforwardly by visual inspection and determined by spectrophotometry. This novel approach is simple, rapid, and sensitive.     

离子液体化香豆素基氰离子比色-荧光探针

设计合成了含咪唑鲔盐结构的离子液体化荧光探针分子CCN,其结构用1HNMR及MS进行了表征,考察了其光谱性能。结果表明,在乙腈中,CCN在常见阴离子（F-、C1-、Br-、I-、CH3COO-、HSO4-、H2PO4、CN-）中能够专一性的识别CN-,滴加CN后引起吸收光谱蓝移100nm,溶液颜色由黄绿色变为无色,荧光猝灭21倍,其他阴离子的存在并未干扰CCN对CN-的检测。     

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

Two rhodamine-based Hg^2 + probes L1 and L2 were prepared and confirmed by NMR, MS and crystal data. The sensing behavior of these probes was studied by UV–visible and fluorescence spectroscopy. The probe L1 couldn't be widely applied in aqueous media or mixed media because of its poor solubility. However, the probe L2 displayed selective and sensitive fluorescence enhancement response to Hg^2 + at physiological pH value for biological use. The selectivity of this system for Hg^2 + over other metal ions was remarkably high, and its sensitivity was at ppb level. The probe L2 responded rapidly to Hg^2 + in aqueous solutions with a 1:1 stoichiometry and was successfully applied to image Hg^2 + in living cells.     

A simple,azulene-based colorimetric probe for the detection of nitrite in water

We describe the synthesis and evaluation of an azulene-based chemodosimeter for nitrite. The probe was found to undergo two distinct color changes upon introduction of aqueous nitrite ion. A near-instant formation of a grey color provides a qualitative indication of the presence of nitrite, followed by the formation of a deep-yellow/orange color, the endpoint from which quantitative data can be derived. The azulene probe exhibits 1:1 stoichiometry of reaction with nitrite in water, and is selective for nitrite over other anions. The azulene probe was applied to determine nitrite content in cured meat, and compared with the British Standard testing procedure (Griess test). The value obtained from the azulene-based probe agreed closely with the standard test. Our procedure only requires the preparation of one standard solution, instead of the three required for the standard Griess test.     

Evaluation of cysteine as environmentally friendly corrosion inhibitor for copper in neutral and acidic chloride solutions

The efficiency of cysteine as a non-toxic corrosion inhibitor for copper metal in 0.6 M NaCl and 1.0 M HCl has been investigated by electrochemical studies. Potentiodynamic polarization measurements and electrochemical impedance spectroscopy “EIS” were used to study the effect of cysteine on the corrosion inhibition of copper. Inhibition efficiency of about 84% could be achieved in chloride solutions. The presence of Cu²⁺ ions increases the inhibition efficiency to 90%. Potentiodynamic polarization measurements showed that the presence of cysteine in acidic and neutral chloride solutions affects mainly the cathodic process and decreases the corrosion current to a great extent and shifts the corrosion potential towards more negative values. The experimental impedance data were analyzed according to a proposed equivalent circuit model for the electrode/electrolyte interface. Results obtained from potentiodynamic polarization and impedance measurements are in good agreement. Adsorption of cysteine on the surface of Cu, in neutral and acidic chloride solutions, follows the Langmuir adsorption isotherm. The adsorption free energy of cysteine on Cu (−25 kJ mol⁻¹) reveals a strong physical adsorption of the inhibitor on the metal surface.     

Hydrophobicity regulation by a facial bromine substitution in MIL-47(V) for highly selective adsorptive desulfurization

Metal organic frameworks (MOFs) have shown promising adsorptive desulfurization (ADS) capacity yet remains great challenges to maintain excellent performance in presence of water. Guided by the density function theoretical (DFT) calculations, we select bromine modified linkers with different substitution degrees to construct MIL-47-xBr to regulate the porosity and hydrophobicity. The optimized MIL-47-Br exhibits the highest saturation dibenzothiophene (DBT) capacity of 179.2 mgS g⁻¹ from the hydrous oil, surpassing the record of all ADS adsorbents. Meanwhile, the excellent selectivity, adsorption kinetics, and recycle stability endow MIL-47-Br with superior ADS performance from the commercial hydrous gasoline. With the DBT capacity decreases by only 12.3% from the commercial gasoline, a continue flow ADS is successfully achieved on the fixed-bed of MIL-47-Br column. Therefore, this facial strategy of simple substitution can fully exploit the functions of open metal sites for enhancing the task-specific selectivity, and has a promising application prospect in industrial ADS.     

一种制备二苯亚砜的高选择性氧化方法

以正丁醇为溶剂,过氧化氢为氧化剂,在异丙醇／磷酸的催化作用下,二苯硫醚被氧化为二苯亚砜。该反应条件温和,选择性高,二苯亚砜的收率达98．7％。     

A sensitive and selective near-infrared fluorescent probe for mercuric ions and its biological imaging applications

A new mercury(II) near-infrared region fluorescent probe 3,9-dithia-6-monoazaundecane-tricarbocyanine has been designed and synthesized. It consists of two functional moieties: the tricarbocyanine performs as the near-infrared region fluorophore, and the 3,9-dithia-6-monoazaundecane acts as the selected binding site for metal ions. The near-IR excitation and emission profiles of the probe can minimize cell and tissue damage and avoid native fluorescence from natural cellular species. It exhibits fluorescence increase upon the binding of the Hg(2+) based on the inhibition of the photoinduced electron transfer quenching mechanism. Excellent sensitivity and selectivity for mercuric ions are observed with this probe. The value of the system is demonstrated by its use in monitoring the real-time uptake of Hg(2+) within HepG2 cells and five day old zebrafish. The synthesis and remarkable properties of it help to extend the development of metal ions fluorescent probes for biological applications.     

A highly selective and sensitive fluorescence chemosensor based on optically active polybinaphthyls for Hg

The chiral polymer was synthesized by the polymerization of 4,7-diethynylbenzo[2,1,3]-thiadiazole (M-1) with (R)-6,6′-dibutyl-3,3′-diiodo-2,2′-bis(diethylaminoethoxy)-1,1′-binaphthyl (R-M-1) via Pd-catalyzed Sonogashira reaction. The chiral polymer has orange fluorescence due to the extended π-electronic structure between binaphthyl unit and benzo[2,1,3]thiadiazole (BT) group via ethynyl bridge. The responsive optical properties of the polymer on various metal ions were investigated by fluorescence spectra. The fluorescence of the chiral polymer can produce the pronounced enhancement as high as 1.8-fold upon addition of 1:2 molar ratio of Hg²⁺. Compared with other cations, such as K⁺, Mg²⁺, Pb²⁺, Co²⁺, Ni²⁺, Ag⁺, Cd²⁺, Cu²⁺, Zn²⁺, Mn²⁺ and Fe³⁺, Hg²⁺ can produce the pronounced fluorescence response of the polymer. The result indicates this kind of chiral polybinaphthyls incorporating diethylamino and benzo[2,1,3]thiadiazole (BT) moieties as receptors exhibits highly sensitive and selective behavior for Hg²⁺ detection.     

A polyamidoamine dendrimer as a selective colorimetric and ratiometric fluorescent sensor for Li+ cations in alkali media

In a DMF + NaOH medium, a polyamidoamine dendrimer having sixteen 1,8-naphthalimide fragments in its periphery, formed a complex only with Li⁺ ions, detected by a colour change from red to yellow and by a significant increase in fluorescence intensity. The dendrimer can be used as a selective sensor for Li⁺ ions in the presence of other alkali ions such as Na⁺ or K⁺.     

芳香亲核取代氢反应及4-氨基二苯胺的合成

芳香亲核取代氢反应是一种环境友好的有机合成反应。4-氨基二苯胺是一种重要的工业中间体,在它的合成过程中对环境污染严重。Flexsys公司将芳香亲核取代氢反应应用于4-氨基二苯胺的合成,解决了环境污染问题。并因此荣获1998年度美国总统绿色化学挑战奖。本文介绍了4-氨基二苯胺的传统合成方法,进而又介绍了芳香亲核取代氢反应的机理及其在4-氨基二苯胺合成中的应用。