Fluorescent Chemosensor For Hg2 Research Articles

A fluorescent chemosensor for Hg(II) optical recognition: Mesoporous MCM-41 functionalized with a covalently linked Eu(III) complex

Mercury widely spreads in atmosphere, lithosphere, and surface water. Concentrated mercury levels could be harmful for individuals with neurological diseases because of bioaccumulation of mercury within brains and kidneys. Mercury is thus considered to be a very dangerous element by the United States Environmental Protection Agency due to the severe immunotoxic, genotoxic, and neurotoxic effects. Consequently, the detection of mercury ions is an important issue for environment and human health. An easily synthesized Eu(III) complex of Eu(PTA) is covalently grafted to the ordered functionalized mesoporous MCM-41 backbone, hoping to explore a novel fluorescence chemosensor with high sensitivity and selectivity for Hg(II) detection in aqueous solution. Fourier transform IR, Small-angle X-ray diffraction, High-Resolution TEM, Nitrogen adsorption/desorption, UV-vis absorption and emission have been employed to characterize the organically modified mesoporous material. The Eu-MCM-41 based chemosensor exhibits a high selectivity for Hg(II), and has a good linearity within the range of 1–12 µmol/L in aqueous solution, suggesting the possibility for real-time qualitative or quantitative detection of Hg(II), as well as a wide potential application in environmental monitoring. The recognition of Hg(II) in actual samples from different sources has been examined by this chemosensor. Additionally, the sensing mechanism of Eu-MCM-41 based chemosensor towards Hg(II) is also investigated and discussed in detail.

Novel colorimetric and fluorescent chemosensor for Hg2+/Sn2+ based on a photochromic diarylethene with a styrene-linked pyrido[2,3-b]pyrazine unit

In this work, two structurally novel isomeric diarylethene chemosensors based on a styrene-linked pyrido[2,3-b]pyrazine unit were synthesized by using Heck coupling reaction. Interestingly, the two reported chemosensors exhibited quick colorimetric sequential responses towards Hg2+ and then Sn2+. Furthermore, the fluorescence intensity of the diarylethene-mercury dyad 1O′ was significantly quenched due to the formation of a new complex 1O-Hg2+. 1O-Hg2+ could be used as a new platform for rapid detection of Sn2+, which involved a conspicuous fluorescence enhancement in the detection progress. Based on the fact that the fluorescence of luminogen 1O could be effectively adjusted by the stimulations of light and metal ions, an integrated combinational logic circuit was constructed with 365 nm UV light, Hg2+ and Sn2+ as input signals and the fluorescence intensity at 560 nm as output signals.

Thiocarbohydrazide based Schiff Base as a Selective Colorimetric and Fluorescent Chemosensor for Hg2+ with “Turn‐Off” Fluorescence Responses

AbstractAn efficient thiocarbohydrazide based fluorescencesensor S5 for the selective detection of Hg2+ in semi‐aqueous medium has been successfully designed and synthesized. The absorption (UV‐Vis) and emission (fluorescence) properties of S5 were studied in various solvents. The sensor S5 displayed no distinct changes in absorption with various solvents; however some remarkable changes were noticed in fluorescence studies. Solvent dependent spectral characterization of S5 was explored via the Lippert‐Mataga plot. UV‐Vis and fluorescence studies also revealed that the sensor S5 could selectively detect Hg2+ ion over the other tested metal ions. The interaction of S5 with Hg2+ leads to colour change from colourless to yellow. The observed quenching in fluorescence intensity may be due to chelation enhanced fluorescence quenching (CHEQ). The sensing mechanism was arrived through DFT and 1H NMR titration studies. The limit of detection was found to be 1.26 nM with a wide pH range of 4–10. Moreover, sensor S5 could demonstrate sensing efficiency for lower concentrations of Hg2+ in real sample analysis. Its performance, as a test strip and in analysis of various water samples conferred its superior selectivity.

Novel multi-responsive fluorescence switch for Hg2+ and UV/vis lights based on diarylethene-rhodamine derivative

A new multi-responsive fluorescent switch DTE-Pip-Rho 1O has been designed and synthesized in this study. For this molecule, the reactive site of spirolactam ring is far away from the diarylethene unit through the intramolecular piperazine. It exhibited high selectivity and sensitivity to Hg2+ in addition to obvious color change (colorless-pink) and fluorescence “off-on” (dark-orange) during this process. It is believed that the color change is due to Hg2+-assisted hydrolysis of rhodamine hydrazide. Therefore, the new molecule can be used as colorimentric and fluorescent chemosensor for Hg2+ with high selectivity. The detection limits of absorbance and fluorescence for Hg2+ were calculated to be 1.15 μM and 1.16 μM, respectively. The resulting DTE-Pip-Rho 1O-Hg2+ could also function as a reversible fluorescence photo-switch in response to UV/vis light owing to FRET mechanism. Moreover, it has been demonstrated that the photo-switchable system displayed excellent fatigue resistance and remarkable anti-photobleaching capability.

A nanomolar detection of mercury(II) ion by a chemodosimetric rhodamine-based sensor in an aqueous medium: Potential applications in real water samples and as paper strips

A new promising rhodamine based colorimetric and fluorometric chemosensor, RDV has been designed and synthesized for specific detection of Hg2+ ion. It acts as highly selective "turn-on" fluorescent chemosensor for Hg2+ ion without interference from other competitive metal ions in aqueous acetonitrile medium. The drastic color change with addition of Hg2+, from colorless to pink, indicates RDV can acts as "naked-eye" indicator for Hg2+. The Hg2+ promoted selective hydrolysis of appended vinyl ether group in RDV followed by Hg2+ chelated complex formation with concomitant opening of spirolactam ring is the plausible sensing mechanism. The detailed absorption, fluorescence, 1H NMR, 13C NMR and mass spectrometry confirms the proposed sensing mechanism. The limit of detection (LOD) of Hg2+ by RDV is 136 nM indicating the high sensitivity towards Hg2+. The RDV shows consistent spectroscopic response in biological pH range 4-10. In addition to explore practical applicability of RDV, its paper strips have been made and used to detect Hg2+ in pure water solution up to 10 ppm level. Furthermore, the potential application of RDV for the sensing of Hg2+ in real water samples (tap water and drinking waters from different sources) were also monitored and demonstrated.

Highly sensitive and selective determination of Hg(II) based on microfluidic chip with on-line fluorescent derivatization

In this study, a convenient, sensitive, rapid and simple method was developed on microfluidic chip which was integrated with on-line complexing and laser-induced fluorescence detection. A rhodamine derivative (RD) was developed as a fluorescent chemosensor for Hg(II). It exhibited high selective recognition toward Hg(II) over other examined metal ions in water samples. Under the optimized conditions, the response was linearly proportional to the concentration of Hg(II) in the range of 0–70 μM with a detection limit of 0.031 μM. Satisfactory repeatability and reproducibility were achieved, with a relative standard deviation (RSD) of 6.62%. The established method was successfully applied for the determination of Hg(II) in environmental water samples (surface water, tap water, and waste water). Recoveries obtained for the determination of Hg(II) in spiking samples ranged from 85% to 103%.

A colorimetric and fluorescent chemosensor for Hg2+ based on a photochromic diarylethene with a quinoline unit

A new colorimetric and fluorescent ‘on–off’ chemosensor, 1O, based on a photochromic diarylethene with a quinoline unit was designed and synthesized. The chemosensor 1O demonstrated selective and sensitive detection of Hg2+ ions in the presence of other competitive metal ions in acetonitrile. The stoichiometric ratio of the sensor 1O for Hg2+ was determined to be 1 : 1, and the limit of detection of the probe 1O was calculated to be 56.3 nM for Hg2+. In addition, a molecular logic circuit with four inputs and one output was successfully constructed with UV/vis light and metal-responsive behavior. ESI-MS spectroscopy, Job's plot analysis, and 1H NMR titration experiments confirm the binding behavior between 1O and Hg2+.

A novel ferrocenyl-based multichannel probe for colorimetric detection of Cu(II) and reversible fluorescent “turn-on” recognition of Hg(II) in aqueous environment and living cells

Ferrocenyl-based carbazole derivative has been synthesized by a simple one-step reaction and characterized by 1H NMR, 13C NMR, ESI-MS and X-ray analysis. Meanwhile, The newly synthesized receptor 1 displayed reversible fluorescent “turn on” response toward Hg2+ with good quantum yield in aqueous environment. The color of the solution containing receptor 1 changed from colorless to yellow upon the addition of Cu2+ ions. Therefore, receptor 1 can act as a fluorescent chemosensor for Hg2+ and a naked-eye probe for Cu2+ in aqueous environment. Quantification of absorption titration analysis shows that the detection limit was 6.15×10−7M for 1-Cu2+ and 3.16×10−7M for 1-Hg2+, respectively. Finally, the receptor 1 has been used successfully for determination of Hg2+ in living cells.

The fluorescent property of 3-[(2-hydroxy-1-naphthyl) methylideneamino]benzoic acid and its application as fluorescent chemosensor for Hg2 + and Al3 + ions

This manuscript studies the fluorescent property of 3-[(2-hydroxy-1-naphthyl)methylideneamino]benzoic acid (H2L). Fluorescent spectra show that in different solvents, H2L displays different fluorescent properties, which can be attributed to the interaction between the solvents and H2L. Further study indicates that H2L exhibits a highly selective and sensitive recognition for Hg2+ ions in dimethylsulfoxide (DMSO), Al3+ ions in methanol and N,N′-dimethylformamide/water (DMF/H2O, 1/1, v/v). The bonding modes and bonding ratio of H2L and metal ions in different solvents are explored by Job's plot, 1H NMR titration, and electrospray ionization mass spectrometry (ESI-MS). The probable mechanisms were discussed.

Fluorescent chemosensors for Hg2+ detection in aqueous environment

Mercury is a pollutant extremely toxic to the environment and human health. Although numerous methods have been reported for the analysis of Hg2+ ions in water, the development of simple, rapid, inexpensive, and sensitive sensors still represents a challenge. Here, we describe the design, synthesis and spectral characterization of a set of dansyl-amino acids able to recognize Hg2+ ions via different fluorescence emission modes. The analysis of the binding features of the different chemosensors shows that the stoichiometry of the sensor–Hg2+ complex depends on the concentration of the sensor and Hg2+ since it plays an important role in the type of response for Hg2+ ions. Among those studied here N-dansylated methionine is the best performing chemosensor in terms of sensitivity with a LOD of 140nM. To improve the LOD of this chemosensor, we evaluated the response of a portable experimental set-up based on optical fiber probes. The new device shows an increase of LOD from 140nM to about 5nM, which can meet the requirements imposed by the Environmental Protection Agency for monitoring Hg2+ in drinkable water. We also show that the chemosensors are not applicable to marine water-based matrices because of the significant coordinating ability of chloride anions with Hg2+.

A bis-hydrazone derivative of 2,5-furandicarboxaldehyde with perfect hetero-atomic cavity for selective sensing of Hg(II) and its intracellular detection in living HeLa S3 cell

A new bis-hydrazone derivative of 2,5-furandicarboxaldehyde (R1) was designed with perfect hetero-atomic cavity and synthesized for sensing of heavy metal ion via FRET mechanism. Selective sensing ability of R1 as a ‘turn on’ fluorescent chemosensor for Hg2+ with rapid and very sharp visual colour change was observed. The long wavelength fluorescence emission of R1:Hg2+ complex was applied for intracellular Hg2+ detection in living HeLa S3 cells. Single crystal X-ray confirmed the structure and LOD calculation suggested that the sensor could identify very low concentration (3.6nM) of Hg2+. Quantum chemical (DFT) calculation supported the symmetrical three dimensional structural arrangements as well as the chelate complex of the sensor with Hg2+.

An Hg2+-selective chemosensor based on the self-assembly of a novel amphiphilic block copolymer bearing rhodamine 6G derivative moieties in purely aqueous media

An amphiphilic block copolymer-based colorimetric and fluorescent chemosensor for Hg2+was prepared, which was synthesized by sequential RAFT polymerization of NIPAM and R6GDM (a novel Hg2+-sensitive rhodamine monomer).

Colorimtric and “turn-on” fluorescent for Hg2+ based on rhodamine-3,4-ethylenedioxythiophene derivative

We designed a novel fluorescent chemosensor for Hg2+ imaging in living cells based on rhodamine hydrazone and 3,4-ethylenedioxythiophene (EDOT). The selective fluorescence response of 1 to Hg2+ is due to the Hg2+-promoted desulfurization of the thiocarbonyl moiety, leading to the ring-opening of rhodamine B moiety of 1. The titration results show a 2:1 complex formation between 1 and Hg2+. The reversibility of chemosensor 1 is verified through its spectral response toward Hg2+ and S2− titration experiments. Chemosensor 1 can be utilized as an inhibit logic gate at molecular level.

Rhodamine hydrazone derivatives bearing thiophene group as fluorescent chemosensors for Hg2+

Rhodamine derivatives bearing the thiophene (1) and bisthiophene (2) groups are synthesized and their binding selectivity toward various metal ions was studied. The X-ray crystal structure of 1 was also reported. Probes 1 and 2 showed highly selective “Off–On” fluorescence changes with Hg2+ among various metal ions. These selective changes were attributed to the spirolactam ring opening processes and subsequent hydrolysis. Probes 1 and 2 were sucessfully applied to the cell-imaging of Hg2+ using HeLa cells.

A NBD-based selective colorimetric and fluorescent chemosensor for Hg2+

A new NBD-based sensor bearing a dipicolylamine derivative, (2-pyridylmethyl)(2-quinolylmethyl)amine (1), was synthesized, and its chromogenic and fluorogenic behaviors toward various metal ions were investigated in methanol solution. Chemosensor 1 selectively detected Hg2+ ions through color change from yellow to colorless. In addition, chemosensor 1 exhibited highly Hg2+-selective ON–OFF fluorescence quenching behavior and was shown to discriminate various competing metal ions, particularly, such as Cu2+, Ag+, and Pb2+. The binding mode of 1-Hg2+ was found to be a 1:2 complex formation, based on Job plot and 1H NMR titration.

Two Highly Sensitive and Selective Colorimetric “Off-On” Rhodamine-Based Fluorescent Chemosensor for Hg(II) in Aqueous Media

Two novel rhodamine derivatives were designed and synthesized. They were successfully characterized by HR-MS, (1)H NMR and (13)C NMR. They were found to exhibit a reversible colorimetric response and exhibit high selectivity and sensitivity for Hg(II) ion over other commonly coexistent metal ions. Their selectivity is excellent, and the detection of Hg(II) at ppb level is possible. The colorimetric and fluorescent response to Hg(II) can be conveniently detected even by the naked eye, which provides a facile method for visual detection of Hg(II).

Specific ratiometric fluorescent sensing of Hg2+via the formation of mercury(ii) barbiturate coordination polymers

A structurally simple and easily synthesized anthracene derivative bearing a barbituric acid moiety (AnB) was developed as a novel fluorescent chemosensor for Hg2+ in terms of specific ratiometric fluorescence response to Hg2+ in aqueous solution via the formation of Hg2+–AnB coordination polymers.

An acyclic, dansyl based colorimetric and fluorescent chemosensor for Hg(II) via twisted intramolecular charge transfer (TICT)

An efficient fluorescent chemosensor for Hg2+ ion, based on 5-(dimethylamino)-N-(2-mercaptophenyl)naphthalene-1-sulfonamide, has been developed. It exhibits Hg2+-selective on–off fluorescence quenching behavior via twisted intramolecular charge transfer (TICT) mechanism, which is rationalized by time dependent density functional theory (TD-DFT) calculations. The system exhibits visible color change from colorless to gray upon Hg2+ binding with very high selectivity and sensitivity (as low as 5.0×10−10molL−1) over other metal ions such as K+, Na+, Ag+, Mn2+, Ca2+, Ba2+, Fe2+, Zn2+, Pb2+, Cu2+, Sn2+, Cd2+, Ni2+ and Co2+. The present sensing system is also successfully applied for the detection of Hg2+ ion in real samples.

A New Rhodamine-Based “Off-On” Fluorescent Chemosensor for Hg (II) Ion and its Application in Imaging Hg (II) in Living Cells

A novel rhodamine derivative (Rh-C), synthesized by the reaction of rhodamine ethylenediamine and cinnamoyl chloride, was evaluated as a chemoselective Hg(2+) ion sensor. Addition of Hg(2+) to an ethanol aqueous solution of the Rh-C resulted in a color change from colorless to obvious pink color together with distinctive changes in UV-vis absorption spectrum and fluorescence spectrum. However, other common alkali-, alkaline earth-, transition- and rare earth metal ions induced no or minimal spectral changes. The interaction of Hg(2+) and sensor Rh-C was proven to adopt a 1:1 binding stoichiometry and the recognition process is reversible. The chemosensor displayed a linear response to Hg(2+) in the range of 0.4-5 μM with a detection limit of 7.4 × 10(-8) M. The sensor Rh-C was also successfully applied to the imaging of Hg(2+) in HL-7702 cells.

A new fluorescent chemosensor for Hg2+ in aqueous solution

We prepared an aminothiourea-derived Schiff base (DA) as a fluorescent chemosensor for Hg(2+) ions. Addition of 1 equiv of Hg(2+) ions to the aqueous solution of DA gave rise to an obvious fluorescence enhancement and the subsequent addition of more Hg(2+) induced gradual fluorescence quenching. Other competing ions, including Pb(2+), Cd(2+), Cr(3+), Zn(2+), Fe(2+), Co(3+), Ni(2+), Ca(2+), Mg(2+), K(+) and Na(+) , did not induce any distinct fluorescence changes, indicating that DA can selectively detect Hg(2+) ions in aqueous solution.