Chemosensor For Detection Of Hg2 Research Articles

Synthesis of spiro-oxindole-based chemosensor for detection of Hg2+ ions using SBA-Pr-N-IS-Bu-SO3H

Spiro-oxindoles were prepared efficiently via multicomponent reactions (MCRs) for finding the new chemosensors. Also, the use of the efficient nanocatalysts based on SBA-15 in these reactions are so important. Therefore, the functionalization of SBA-15 by different organic compounds are common to produce new efficient nanocatalysts. Herein, SBA-Pr-N-Is-Bu-SO3H as an efficient nanoporous catalyst was applied in the synthesis of (5,6,7,8-tetrahydro-chromene)-4,3′-spirocyclic oxindoles through the three-component reaction of isatin derivatives, malononitrile and dimedone under reflux conditions in high yield and short reaction time. Among all spiro-oxindole derivatives, 2-amino-7,7-dimethyl-5′-nitro-2′,5-dioxo-5,6,7,8-tetrahydro-spiro[chromen-4,3′-indoline]-3-carbonitrile was investigated in fluoresence spectroscopy. According to the obtained results it was observed that in the presence of various cations such as, K+, Ca2+, Na+, Cu2+, Zn2+, Cr3+, Fe3+, Fe2+, Mn2+, Co2+, Al3+, Pb2+, Ag+, Cd2+, Ni2+, Hg2+ and Mg2+, it can selectively detect Hg2+ ion and increase the emission intensity. Its calculated detection limit was 4.6 × 10−7 M, which can be considered a good value. Also, in order to determine the stoichiometric ration for ligand and Hg2+ ion, Job's plot test was performed and the ratio was 1:2.

A dual-channel colorimetric and ratiometric fluorescence chemosensor for detection of Hg2+ ion and its bioimaging applications

A new colorimetric and ratiometric fluorescence chemosensor 4-((3-(octadecylthio)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4DBS) was synthesized and investigated for the selective detection of Hg2+ in DMSO-H2O (9:1, v/v) solution. The chemosensor was efficiently synthesized in two steps via Michael-like addition and nucleophilic substitution reactions. The ratiometric fluorescence turn-on response was obtained towards Hg2+, and its fluorescence emission peak was red-shifted by 140 nm with an associated color change from light maroon to pale yellow due to the intramolecular charge transfer effect. The formed coordination metal complex was further evaluated by FT-IR, 1H NMR, and quantum chemical analyses to confirm the binding mechanism. The detection process was sensitive/reversible, and the calculated limit of detection for Hg2+ was 0.451 µM. Furthermore, 4DBS was effectively utilized as a bioimaging agent for detection of Hg2+ in live cells and zebrafish larvae. Additionally, 4DBS showed distinguishing detection of Hg2+ in cancer cells in comparison with normal cells. Thus, 4DBS could be employed as an efficient bioimaging probe for discriminative identification of human cancer cells.

Novel rhodamine based chemosensor for detection of Hg2+: Nanomolar detection, real water sample analysis, and intracellular cell imaging

A novel fluorescent chemosensor PS founded on rhodamine 6G for Hg2+ has been synthesized and authenticated by employing 1H NMR, 13C NMR, and LC–MS skills. The fluorescent chemosensor displays an intense selectivity and sensitivity for Hg2+ over additional metal ions explored in the combined organic aqueous phase. A strong fluorescence enhancement was detected after the addition of Hg2+, which was accompanied by ring-opening of a rhodamine spiro-cyclic structure. The stoichiometric ratio of the PS-Hg2+ complexes was determined to be 1:1 according to Job’s plot and 1H NMR experiment. The binding constant and limit of detection (LOD) for PS-Hg2+ complexation is estimated to be 6 × 104 M−1 and 3.0375 × 10-8 M (30.37 nM), respectively. The extreme fluorescent enhancement caused by Hg2+ binding in chemosensor PS occurred at a pH range of 6−8. Owing to practical application, the Hg2+ metal ion was efficiently determined using a spike and recovery approach from real water samples. Additionally, the probe PS was further used in the cell imaging experiment for the detection of the Hg2+ intracellularly using MDA-MB-231 and A375 breast cancer cells by MTT assay method with low cytotoxicity.

Multiple doping effect of LiYF4:Yb3+/Er3+/Ho3+/Tm3+@LiYF4:Yb3+ core/shell nanoparticles and its application in Hg2+ sensing detection

We report the synthesis of lanthanide-doped core/shell upconverting nanoparticles (UCNPs) LiYF4:Yb3+/Er3+/Ho3+/Tm3+@LiYF4:Yb3+. The photoluminescence (PL) spectra of the tetragonal-phase nanoparticles could be tuned by varying the doping ratio of lanthanide ions (Er3+, Ho3+, Tm3+) and their intensities were much enhanced through the active core/active shell strategy. The as-synthesized UCNPs were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM), and PL spectroscopy. By varying the composition and concentration of the dopant ions, the upconversion emissions upon near-infrared (NIR) excitation at 980 nm can be precisely modulated. After overcoating UCNP cores with LiYF4:Yb3+ shell, the upconversion emissions for all core/shell nanoparticles were about 3 times of those corresponding core nanoparticles. After ligand exchange, the hydrophobic LiYF4:Yb3+/Er3+/Ho3+/Tm3+@LiYF4:Yb3+ core/shell nanoparticles could be transferred into hydrophilic UCNPs. The colloid nanoparticles could be employed as a chemosensor for detection of Hg2+ at near-infrared excitation wavelengths.

A fluorescent Cd(II) based 2-D coordination polymer for highly selective detection of nitroaromatics and Hg2+

A 2-D Cd(II) coordination polymer (CP), {[Cd2(L)2(4,4′-bipy)2(H2O)∙7H2O]n (1), has been synthesized using 5-aminoisophthalic acid (H2L) as ligand and 4,4′-bipyridine as co-ligand. A single-crystal X-ray diffraction study shows that 1 is an infinite 2-D layer. CP 1 behaves as a highly selective and sensitive fluorescence chemosensor for detection of Hg2+ and 2,4,6-trinitrotoluene (TNT). Furthermore, possible emission quenching in 1 in the presence of nitroaromatics has been addressed with the aid of theoretical calculations. The calculations indicated that there are both electron and energy transfer processes, in addition to electrostatic interaction between 1 and nitroaromatics which contributes to the selective fluorescence quenching.

A colorimetric and fluorescent chemosensor for detection of Hg2+ using counterion exchange of cationic polydiacetylene

In this study, a colorimetric and fluorescent chemosensor for mercury ions (Hg2+) was developed. Cationic polydiacetylene (PDA) vesicles with a quaternary ammonium cation and iodide as a counterion show a blue-to-red color transition; the color change is accompanied by a fluorescence enhancement in selective response to Hg2+ ions because of a perturbation of the ene–yne conjugated backbone induced by counterion exchange. It allows for selective detection of Hg2+ with the naked eye and the sensor is used to determine Hg2+ concentrations in tap water samples.

An Extremely Stable 2D Zinc(II) Coordination Polymer Exhibiting High Sensing Ability and Photocatalytic Degradation Activities of Dyes

A new 2D Zn(II) metal-organic framework of {[Zn(L)(4,4′-bipy)·CH3CN]n (1) has been developed using 5-aminoisophthalic acid (H2L) and 4,4′-bipyridine ligands. The single crystal X-ray diffraction study indicates that 1 is composed of infinite 2D layer. The chemically stable 1 behaves as a highly selective and sensitive fluorescence chemosensor for detection of Hg2+ and 4-nitrotoluene (4-NT) analyte. Furthermore, the photocatalytic properties of 1 for degradation of the methyl violet (MV) and Rhodamine B (RhB) have been explored.

Spectral studies on anthracene based dual sensor for Hg2 + and Al3 + ions with two distinct output modes of detection

A simple and easily synthesized colorimetric and fluorescent chemosensor 1, based on aromatic OH and imine moieties as a binding and anthracene as signaling unit, has been synthesized in a one-step procedure. The chemosensor 1 is developed as a dual chemosensor for detection of Hg2+ and Al3+ ions in CH3OH, which exhibited a color change from light yellow to dark yellow with Hg2+ ions, enabling 1 a suitable “bare eye” indicator for Hg2+ ions. On the other hand, fluorescent enhancement with blue shift along with brilliant cyan fluorescence was observed upon binding with Al3+ ions. A possible sensing mechanism has been proposed by means of Job's plot and 1H NMR titration.

Highly selective fluorescent and colorimetric chemosensor for detection of Hg2 + ion in aqueous media

A highly efficient and selective fluorescent and colorimetric chemosensor based on naphthothiazole skeleton was synthesized and its colorimetric and fluorescent properties were investigated. The sensor displays a rapid and highly selective colorimetric and fluorescence response toward Hg2+ without interference with other metal ions in CH3CN/H2O mixture (50/50, v/v). The detection limit for the fluorescent chemosensor S1 toward Hg2+ was 3.42×10−8M.

A selective and sensitive “naked-eye” rhodamine-based “turn-on” sensor for recognition of Hg2+ ion in aqueous solution

A selective and sensitive “naked-eye” rhodamine-based “turn-on” chemosensor for detection of Hg2+ ion over other metal ions such as Ni2+, Ca2+, Ba2+, Cs+, Fe3+, Mn2+, Cd2+, Zn2+, Mg2+, K+, Ag+, Hg2+, Co2+, and Pb2+ in aqueous solution was prepared. Meanwhile, a new method for the synthesis of rhodamine amide directly from rhodamine hydrazide in the presence of NaH was reported for the first time. It was observed that once Hg2+ ion was added to the sensor 4, a 91.4-fold enhancement of the absorption at 570nm was observed. Its selectivity toward Hg2+ ion was very high, and little interference was detected for other commonly coexistent metal ions. The fluorescent intensity was almost a constant minimal value when pH=5–8 in aqueous solution. It demonstrated that Hg2+ could be detected at least down to 3×10−8M. Moreover, the Hg2+-promoted selective desulfurization reaction was further confirmed by MS spectra. The present probe could be used to determine Hg2+ ion concentrations in aqueous environments.

A Novel Heterogeneous Colorimetric and Spectrophotometric Chemosensor for Detection and Adsorption of Hg<SUP>0</SUP> and Hg<SUP>2+</SUP>

Functionalized mesoporous silica with an immobilized azobenzene-coupled receptor 1 (FMS-1) as heterogeneous "naked-eye" colorimetric and spectrophotometric chemosensor was prepared by sol-gel reaction. The optical sensing ability of FMS-1 was studied by addition of metal ions such as K+, Ca2+, Sr2+, Co2+, Cd2+, Pb2+, Zn2+, Fe3+, Cu2+ and Hg2+ in aqueous solution. Interestingly, upon the addition of Hg2+ in aqueous suspension, FMS-1 resulted in a color change from maroon to red within 10 s. On the other hand, no significant color changes were observed with the other metal ions. These findings confirm that FMS-1 can be useful as a chemosensor for selective detection of Hg2+ over a range of metal ions. Furthermore, the adsorption ability of the FMS-1 was also estimated by measuring the amount of Hg2+ and Hg0 adsorbed on the FMS-1, resulting in 95% for Hg2+ and 75% for Hg0, respectively, suggesting that the FMS-1 is potentially useful as the adsorbent for separation of Hg0 and Hg2+ in chromatography.