Fluorescent Chemosensor For Cu2 Research Articles

A new water−soluble naphthalene diimide as a highly selective fluorescent chemosensor for Cu(II) ion: Synthesis, DFT calculations, photophysical and electrochemical properties

The highly selective, sensitive, and water-soluble fluorescent sensors are desideratum for optoelectronic, environmental, biological, and biomedical applications. An innovative fluorescence chemosensor, naphthalene diimide (3) with metal binding sites, was designed, synthesized and characterized. The chemosensor's optical, electrochemical, spectroelectrochemical, and morphological properties were investigated, and then the density functional theory (DFT) simulations were conducted. The selectivity of 3 for the metals Cu(II), Ag(I), Hg(II), Mg(II), Fe(III), Ca(II), Co(II), Zn(II), Pb(II) and Cd(II) were investigated through UV–visible and fluorescence spectroscopy techniques. 3 was highly selective and sensitive toward Cu(II) metal ions. The chemosensor can detect Cu(II) in water with a detection limit of 1.11 μM, which is lower than the WHO standard and has good repeatability. Further investigations through the IR, DPV, AFM, UV–visible and fluorescence spectroscopies, SEM, EDX and TEM techniques confirmed the binding capabilities of the 3 with Cu(II).

A benzimidazole-derived fluorescent chemosensor for Cu(ii)-selective turn-off and Zn(ii)-selective ratiometric turn-on detection in aqueous solutions

A benzimidazole-derived fluorescent chemosensor for Cu(ii)-selective turn-off and Zn(ii)-selective ratiometric turn-on detection is developed in an aqueous solution.

On the synthesis and performance of a simple colorimetric and fluorescent chemosensor for Cu2+ with good reversibility

A colorimetric and fluorescent chemosensor (CS1) for Cu2+ based on the mechanism of internal charge transfer (ICT) has been successfully designed and prepared by simple condensation of 4_(diethylamino)salicylaldehyde and oxalyl dihydrazide. Cu2+ in solution (DMSO/H2O = 7:3, v/v) by 5 mM NaAc–HAc at pH 7.0 was determined through dual channels: (1) “naked-eye” observation, a visually dramatic color change from light green to orange, which can be used for qualitative determination of Cu2+; (2) spectrofluorometry, which can quantificationally assay Cu2+. It provides a simple-to-use platform for reliable detection of Cu2+ at concentrations ranging from 5.0 × 10−7 to 1.1 × 10−5 M with detection limit of 1.2 × 10−7 M, which is nearly 2 × 102 times lower than the maximum allowable level of inorganic Cu2+ in drinking water (1.3 ppm, ∼20 µM) permitted by the EPA (Environmental Protection Agency), and the sensing detection of Cu2+ ions was reversible.

Chalcone-based fluorescent chemosensors as new tools for detecting Cu2+ ions

The design and full characterization of new fluorescent chemosensors for Cu2+ is herein presented. The structure of the sensors is based on a chalcone backbone as the chromophoric unit, with di-(2-picolyl)amine (DPA) as a receptor moiety. Two systems, bearing one or two chalcone-DPA units, were synthesized and fully characterized.UV–Vis titrations with several metal ions were performed and both chemosensors exhibited a strong hypsochromic shift in the absorption spectra upon Cu2+ addition, indicating a higher selectivity for this metal over other divalent cations. Additionally, fluorescent spectra recorded in the same conditions revealed a stronger quenching effect in the presence of Cu2+, even in the presence of other metal cations, with association constants above 106 M−1 and detection limits below the micromolar level for both chemosensors. Paper test-strips with one of the chemosensors were prepared to attest its possible application for detecting copper in aqueous samples.

A new naked-eye fluorescent chemosensor for Cu(II) and its practical applications

A new naked-eye fluorescent chemosensor for Cu(II) and its practical applications

A rhodamine-based chemosensor and functionalized gel ball for detecting and adsorbing copper ions

Abstract The development of sensitive colorimetric and fluorescent chemosensors for Cu2+ sensing has gained much attention in recent years because of their potential application in clinical biochemistry and environmental studies. Herein, a novel rhodamine-based chemosensor NRG was constructed, which exhibited high sensitivity and selectivity and a quick response for Cu2+, accompanied by remarkable color and fluorescence changes. Moreover, besides sensing Cu2+, NRG can capture Cu2+ effectively and quickly in aqueous solution. Based on the results, NRG-functionalized gel balls were fabricated and exhibited strong adsorbability and a high adsorption capacity for Cu2+, accompanied by an obvious color change. More interestingly, the gel balls can be recycled after treatment with an EDTA solution. These excellent properties make the gel ball a promising candidate for copper ion purification.

A novel fluorescent chemosensor for Cu2+ ion based on a new hexadentate ligand receptor: X-ray single crystal of the perchlorate salt of the ligand, ion selectivity assays and TD-DFT study

New hexadentate chelates, H2L1 and L1, were synthesized. The Schiff base imine ligand, L1, was prepared by reaction of 2,2′-[ethane-1,2-diylbis(oxy)]dibenzaldehyde and propanolamine, and characterized by infrared (IR), 1H NMR and 13C NMR spectroscopies. The amine ligand, H2L1, was prepared in the form of perchlorate salt ([H4L1](ClO4)2,) by reduction of L1 with NaBH4, and was characterized by IR (in KBr pellet), 1H NMR, 13C NMR and 2D NMR correlation spectroscopy (COSY) (in solution). The X-ray crystal structure of [H4L1](ClO4)2 was also determined and discussed. Fluorescence studies showed that H2L1 is a highly selective novel fluorescence chemosensor for the Cu2+ cation. The sensor shows selectivity for Cu2+ over 12 other metal cations. In presence of Cu2+ (5 equivalents in the μM range) the fluorescence emission of the sensor, at 309 nm, is quenched by more than 98%. TD-DFT calculations show that ligand to metal charge transfer transitions in the complex formed between Cu2+ and the amine ligand contribute to the quenching of the fluorescence. An explanation based on TD-DFT results is also proposed for the weak fluorescence quenching in the presence of Zn2+.

Synthesis of quinoline functionalized fluorescent chemosensor for Cu (II), DFT studies and its application in imaging in living HEK 293 cells

New fluorescent probes having quinoline moiety have been successfully synthesized for the selective Cu2+ ions detection. These sensors show a favorable selectivity towards Cu2+ ion over a broad range of other common metal ions in DMSO/H2O (2:8, v/v) HEPES buffer solution (pH = 7.4), leading to remarkable fluorescence on-off response with very low Limit of Detection (LOD) value. The robust nature of the probes was shown by the detection of Cu2+ even after repeated rounds of the experiment. Moreover, the probe can be used to detect Cu2+ in real water samples with a high precision and good accuracy. The recognition mechanism of one representative probe towards Cu2+ has been properly inspected in details by High Resolution Mass Spectrometry (HRMS) and density functional theory (DFT) calculations. Besides, fluorescence imaging studies in HEK 293 cells of that probe is also indicating that the probe is low cytotoxic and offers good photophysical properties, suggesting that this fluorescent chemosensor can be easily used to track Cu2+ ion in cells.

A Novel Fluorescent Chemosensor for cu (II) Ion: Click Synthesis of Dual-Bodipy Including the Triazole Groups and Bioimaging of Yeast Cells.

A fluorescent chemosensor including dual Bodipy units (d-BODIPY) was improved for selective copper (II) sensing in half-aqueous samples. The sensor d-BODIPY has a highly selective and sensitive detection towards Cu (II) over the studied competing for metal cations. The interaction among solutions of Cu (II) and d-BODIPY caused a crucial quenching effect in fluorescence maxima at 548nm (λex= 470nm) owing to the electronic trap occurring between the amide and triazole units. The quenching effect without any change in wavelength can be explained by a photoinduced electron transfer (PET) process. The binding constant (Ka) of d-BODIPY with Cu (II) was calculated and also the limit of detection of d-BODIPY for Cu (II) was 1.2 × 10-8 M. In addition, the bio-imaging in the yeast cells suggested that d-BODIPY had an excellent potential to be used to investigate Cu (II).

A turn-off fluorescent chemosensor for Cu(II) based on sensitive schiff base derived from 4-tert-Butyl-2,6-diformylphenol and p-toluic hydrazide

The novel Schiff base ligand (H3L), [Zn2(HL)(C2H3O2)2](C2H5OH) and [Cu2(H2L)(C2H5O)(NO3)]2(NO3)2 have been facilely and successfully synthesized, where H3L was fabricated using 4-tert-Butyl-2,6-diformylphenol and p-toluic hydrazide resulting in an N2O3 coordination environment. The as-made compounds were characterized by different spectroscopic techniques. The DFT calculations were performed at B3LYP/6–311 G(d) level for the determination of the optimized structure of the synthesized compounds. Further, the molecular structure of Zn-complex was confirmed by single-crystal X-ray diffraction. The interaction of H3L with different metal ions has been examined through the UV–Vis absorption and fluorescent spectra. The results indicated that H3L showed a highly sensitivity and selectivity for Cu2+ in the presence of many other metal cations in ethanolic solution.

Highly selective detection of copper(II) by a “ligand-free” conjugated copolymer in nucleophilic solvents

The synthesis of N-cyclohexyl carbamate-attached fluorene-alt-phenylene copolymer (PFPNCC) and the use of PFPNCC as a “ligand-free” fluorescent chemosensor for Cu(II) are described. Addition of Cu(II) can efficiently quench the fluorescence of PFPNCC in nucleophilic solvents such as DMF and DMSO, but not in low nucleophilic solvents such as 1,4-dioxane and THF. Ultraviolet-visible spectra of the mixture of the conjugated polymer and Cu(II) indicate the presence of a reduced Cu (I) ion in the solution. Furthermore, fluorescence recovery of PFPNCC observed at low temperature suggests that the quenching and reducing mechanism is most probably due to a photo-induced electron transfer from excited PFPNCC to Cu(II). Our findings provide a novel strategy for highly selective conjugated polymer-based chemosensors for various target analytes, albeit “ligand-free”.

A novel coumarin-based ligand: a turn-off and highly selective fluorescent chemosensor for Cu2+ in water

A highly sensitive coumarin-based on–off system for the detection of Cu2+ in water was developed. The system was successfully applied for the detection of Cu2+ at micromolar levels in natural water samples.

Novel chiral aggregation induced emission molecules: self-assembly, circularly polarized luminescence and copper(ii) ion detection

Two novel chiral molecules 1 and 2 were designed and synthesized. 1 displayed evident CPL activity, whereas 2 served as a highly selective and sensitive “turn-off” fluorescent chemosensor for Cu2+.

A fluorescent chemosensor for Cu2+ ions and its application in cell imaging

A new on-off fluorescent probe 1 for Cu2+ based on Schiff base compound was designed and synthesized by one-step reaction. The single probe 1 exhibited strong green fluorescence emission. A fluorescence quenching effect and faint color change were observed as soon as the Cu2+ was added to the probe system in H2O/EtOH (v/v = 8:2, HEPES buffer, 0.05 M, pH = 7.4) solution. Other common metal cations did not cause the changes in the fluorescence and color of the probe 1. The optical properties were studied by the fluorescence emission and UV–Vis spectra. Meanwhile, the geometry optimizations of probe 1 and the [1-Cu2+] coordination complexes were also carried out by DFT using the Gaussian 09 program, in which the B3LYP function was used. Based on experimental measurement and theoretical analysis, we can know that the combination ratio of the probe and Cu2+ is 2:1 and the limit of detection (LOD) is as low as 5.3 × 10−9 M Besides, the probe 1 was also used to analyze the Cu2+ in living cells.

A highly sensitive and selective colorimetric and off–on fluorescent chemosensor for Cu2+ based on rhodamine 6G hydrazide bearing thiosemicarbazide moiety

Abstract A rhodamine derivative (R1) has been synthesized by an additive reaction of rhodamine 6G hydrazide with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Cu2+ under physiological conditions. The detection limit of Cu2+ ion is 47.2 nM. Moreover, R1 could sense Cu2+ by “naked eye” with a color change from colorless to pink. This selective signaling behavior is not affected by other canions that might be present in the environmental samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in HeLa cells was also demonstrated.

A highly selective fluorescent chemosensor for Cu2+ : synthesis and properties of a rhodamine B-containing diarylethene.

A diarylethene bearing a triazole-linked rhodamine B unit was synthesized. Its fluorescent emission was significantly enhanced in the presence of protons or Cu2+ due to transformation from the pirocyclic form to open-ring form. The fluorescence was quenched sequentially upon irradiation with 297nm light based on the intramolecular fluorescence resonance energy transfer mechanism. In an acetonitrile: water binary solvent (1: 1v/v), the compound showed significant fluorescent enhancement for Cu2+ compared with a wide range of tested metal ions with a fast response and a limit of detection of 2.86×10-8 molL-1 . Using Cu2+ and UV light as the chemical inputs, and fluorescence intensity at 597nm as the output, a logic gate was developed at the molecular level. Moreover, the compound can be used with a high accuracy to detect Cu2+ in a natural water sample.

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu(2.).

Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu2+. The 1:1 stoichiometry of the obtained complex has been determined by Job’s plot. The association constant determined by fluorescence titration was found to be 1.8 × 106 M−1. The sensor showed a linear response toward Cu2+ in the concentration range from 1 to 10 µM with a detection limit of 9.6 × 10−8 M.

Thiourea based conjugated polymer fluorescent chemosensor for Cu+ and its use for the detection of hydrogen peroxide and glucose

A novel conjugated polymer, poly(1), containing thiourea moieties in main chain is synthesized via Suzuki coupling reaction. The addition of cuprous ion quenches the fluorescence of poly(1), whereas the fluorescence changes slightly upon addition of other metal ions, exhibiting the fluorescent almost turn-off sensing ability towards Cu+. When hydrogen peroxide was added to the solution containing poly(1) and Cu+, Cu+ was oxidized into Cu2+, resulting in the fluorescence recovery. The H2O2 released from glucose oxidation by glucose oxidase (GOD) also recovered the fluorescence of poly(1)/Cu+ solution. The results indicated that the poly(1)/Cu+ solution could serve as a sensing platform for hydrogen peroxide and glucose.

A bis(pyridine-2-ylmethyl)amine-based selective and sensitive colorimetric and fluorescent chemosensor for Cu2+

A new bis(pyridine-2-ylmethyl)amine derivative (1) was synthesized as a colorimetric and fluorescent chemosensor for metal ions. Experimental results indicate that 1 displays significant colorimetric and fluorescent changes upon binding of Cu2+. Since 1 has a high water solubility as well as good cell-permeability, it successfully applied to detect the presence of Cu2+ ion in HepG2 cells in culture medium. Thus, 1 can be used as a potential Cu2+ chemosensor in aqueous solution and mammalian cells. Further, the fluorescence behavior of 1 upon Cu2+ binding was well explained by our quantum calculation based on electronic structure.

Dual turn-on fluorescent chemosensor for Cu2+ and Hg2+ in aqueous medium based on a water-soluble polyacrylamide containing rhodamine

An acrylic monomer bearing rhodamine 6G group, salicylaldehyde rhodamine 6G hydrazone acrylate (AR6GHS), was synthesized from salicylaldehyde rhodamine 6G hydrazone (R6GHS) and acryloyl chloride in the presence of triethylamine in dry dichloromethane (CH2Cl2) at room temperature. The poly(acrylamide- salicylaldehyde rhodamine 6G hydrazone acrylate) (poly(AM-AR6GHS)) was synthesized by a combiation of AR6GHS and a hydrophilic comonomer acrylamide (AM) with 2,2′-azobis(2-methylpropionitrile) (AIBN) as a thermal initiator in tetrahydrofuran (THF). The resultant AR6GHS and poly(AM-AR6GHS) were identified by FTIR and 1H NMR spectra. The fluorescent characteristic of the poly(AM-AR6GHS) in the aqueous solutions were investigated both in varied pH and in the presence of metal cations. It was found that the copolymeric sensor exhibited “off-on” recognition toward Cu2+ and Hg2+ over a wide range of tested metal ions with remarkably enhanced fluorescent intensities. The poly(AM-AR6GHS) had a good linear response between the relative fluorescence intensity and Cu2+ or Hg2+ concentration. In addition, upon the addition of Cu2+ or Hg2+ into the aqueous solution of poly(AM-AR6GHS), the color changes occurred from colorless to pale pink or pink under visible light, and the emission color of the sensor solution turned from dark to bright greenish yellow or orange yellow under the UV light at 365 nm.