Selective Detection Of Copper Research Articles

Simple excited state intramolecular proton transfer (ESIPT) based probe for pH and selective detection of copper(II) ion in aqueous alkaline environment: Sensitivity, selectivity and logic behavior

A low molecular weight ESIPT-based probe was synthesized and tested for detecting pH, cations, and anions in aqueous solutions. The probe exhibited a good emission in water due to aggregation induced by π-π* stacking. It gave an “off–on” fluorescent response to higher pHs because of blocking the non-radiative ESIPT after deprotonating phenolic hydroxyl groups. Moreover, the fluorescence emission of the probe (water/ethanol = 3:1, pH 10) was quenched only by Cu2+ with limit of detection LOD = 3.2 μM. The stoichiometric ratio of the probe/Cu2+ complex was found to be 1:1. Furthermore, changes of the probe’s absorption and emission signals (as outputs) in response to the presence of H+ and HO– or Cu2+ and Br− stimuli (as chemical inputs) mimics INHIBIT, IMPLICATION and NOT TRANSFER logic gates.

Experimental and computational study on the spectroscopic and colorimetric copper sensing behaviour of three ketimine derivatives

Three imine based colorimetric copper sensors were successfully synthesized and their copper sensing behaviours characterized via absorption spectroscopy and rationalized by density functional theoretical (DFT) calculations. All three compounds interact strongly with copper in non-aqueous and semi- aqueous media, as indicated by the exergonic nature of this process: ΔGbinding = ∼ -28 kJ mol−1, which leads to a visible colour change; a process controlled by entropic effects in combination with the relative hardness of the binding sites. These compounds allow selective detection of copper at concentrations as low as 0.16 ppm with linear ranges of 1–5 ppm and quantification limits as low as 0.52 ppm. Whereas, only zinc leads to reduced accuracy for 2-[1-(2-hydroxyphenyl)ethylideneamino]phenol, at equimolar levels, for the other derivatives, hard-soft interactions allow significant interference from various metals, present at such a concentration. Overall, these compounds represent a viable starting point for the development of cheap colorimetric copper sensors.

A colorimetric chemosensor for sensitive and selective detection of copper(II) ions based on catalytic oxidation of 1-naphthylamine.

Rapid on-site detection of copper(II) ions (Cu2+) with high sensitivity and selectivity is of great significance in the safety monitoring of drinking water and food. Colorimetric detection is a robust fast determination method with the main drawback of low sensitivity. Herein, we developed a colorimetric chemosensor based on a colored polymer product. Via a Cu-Fenton mechanism, 1-naphthylamine (α-NA) was oxidized by H2O2 and brownish-red poly(1-naphthylamine) (PNA) was produced. The obtained Cu2+ sensor showed a linear response from 0.05 μM to 7 μM, with a detection limit of 62 nM. Our findings expanded chromogenic reaction types for colorimetric detection.

Solvent-dependent selective “naked eye” chromofluorogenic multifunctional rhodamine-based probe for Al3+, Cu2+, Hg2+, S2− and CN− ions

The solvent-dependent selective “naked eye” chromofluorogenic multifunctional rhodamine-based probe 3 for Al3+, Cu2+, Hg2+, S2− and CN− ions was synthesized and its spectral, luminescent and ionochromic properties were studied. The compound obtained exists in the spirolactam form, confirmed by data of 1H, COSY, HSQC, HMBC and 13C NMR spectroscopy. In ethanol, Al3+ ions selectively, even in the presence of other metal cations (Na+, Ba2+, Zn2+, Cd2+, Ni2+, Co2+, Cu2+, Hg2+ and Fe3+) initiate the opening of the spirolactam ring, accompanied by the appearance of a new absorption band at 556 nm and the “naked eye” effect with a change in the yellow-green color of the solution to orange-pink. At the same time, the initial fluorescence 3 at 539 nm shifts to the longer 579 nm spectral region. The use of acetone as a solvent allows the selective detection of copper(II) cations that turn the yellow color of a solution of 3 to pink-purple (λabs 563 nm) due to the formation of the ring-open complex 3.Cu2+ that exhibits emission at 580 nm. Selective detection of Hg2+ in acetonitrile results in the “naked eye” effect characterized by a change in the color of the solution from bright yellow to pink-cherry (λabs 564 nm). The fluorescence of the mercury(II) complex is observed at 587 nm. Complexes 3.Cu2+ and 3.Hg2+ were used for the sequential selective recognition of S2− and CN− anions, respectively. A combinatorial molecular logic gate was designed based on the cation/anion sensing ability of probe 3.

A peroxyoxalate chemiluminescence recovery system based on the interaction of N-doped graphene oxide nanosheets and an oligopeptide for ultra-sensitive and selective copper(II) ion detection.

In this paper, a peroxyoxalate chemiluminescence (CL) recovery system based on the interaction of N-doped graphene oxide nanosheets (N-GONs) and an oligopeptide for copper(II) ion detection has been reported. N-GONs as an excellent CL enhancer are prepared by the hydrothermal method using citric acid and ammonia, and the morphology and structure are characterized in detail by TEM, XPS, FT-IR and UV/vis, etc. In the bis(2,4,6-trichlorophenyl)oxalate (TCPO) and hydrogen peroxide (TCPO + H2O2) CL reaction system, the addition of N-GONs gives a remarkable CL emission, which can be quenched by an oligopeptide composed of ten amino acid residues due to the interaction between the N-GON plane and the oligopeptide strand. While in the presence of copper(II) ion, the quenched CL is recovered gradually along with the addition of copper(II) ion in the system. Based on the above CL reactions, a TCPO + H2O2 + N-GONs + oligopeptide CL system is constructed, achieving an ultra-sensitive and selective detection of copper(II) ion in environmental water samples. The detection limit of this method is as low as 0.2 pmol L-1, which is at least three orders of magnitude lower than other CL methods. The N-GONs and oligopeptide involved in the CL system are environmentally friendly, making it possess potential in the detection of copper(II) ion in environmental water samples.

Exploitation of a turn-on photoelectrochemical sensing platform based on Au/BiOI for determination of copper(II) ions in food samples

Copper is an essential element and plays an important role in various physiological processes. Therefore, it is critical to exploit novel assay for effective, rapid, simple and selective detection of copper. Herein, a cathodic turn-on photoelectrochemical (PEC) sensor was developed for the selective and accurate analysis of copper(II) ions (Cu2+) in food samples based on the gold nanoparticles (AuNPs) loaded BiOI nanocomposite (Au/BiOI). By screening and optimizing bismuth oxyhalide semiconductors, the Au/BiOI with a wide visible light response range and low electron recombination efficiency was prepared. Compared with the BiOI alone, the Au/BiOI exhibited about 4-hold enhanced photocurrent intensity. Based on the excellent PEC performances, the Au/BiOI were successfully applied to construct the Cu2+ PEC sensor. Under the optimized conditions, the Au/BiOI-based PEC sensor exhibited excellent linear response with the concentration of Cu2+ from 1 to 50 μM and a low limit of detection (0.4 μM). Moreover, this PEC sensing strategy exhibited a feasible method for Cu2+ detection in food samples with high selectivity and good stability.

Synthesis of dual-emissive ratiometric probe of BSA-Au NCs and BSA-Cu NCs and their sensitive and selective detection of copper and mercury ions

Herein, we synthesized bovine serum albumin-functionalized gold nanoclusters (BSA-Au NCs) and BSA-Cu nanoclusters (Cu NCs) by a facile and environmentally-friendly method, and simply mixed them to develop a ratiometric fluorescent sensor for mercury (Hg2+) and copper (Cu2+) ions detection, respectively. The as-prepared BSA-Au NCs were known to emit pink color fluorescence (peaking at 616 nm) and BSA-Cu NCs were blue-emitting (peaking at 398 nm) upon the exposure of ultraviolet light (365 nm). Among them, BSA-Au NCS was used as the response signal and BSA-Cu NCs was the reference signal. Interestingly, when the easily prepared ratiometric probe were employed to detect 15 kinds of common metal ions, only Hg2+ and Cu2+ ions could significantly quench the pink fluorescence of BSA-Au NCs. We found that the fluorescence intensity ratio (I616 /I398) of the nanohybrid system was efficiently reduced by the addition of Hg2+ and Cu2+ ions compared to a series of metal ions. The response of the nanohybrid probe to Cu2+ showed an excellence linear relationships in the concentration range of 0.1∼1 μM and 1∼5 μM respectively, and its detection limit was 23.4 nM. Moreover, the fluorescence quenching caused by Hg2+ ions exhibited excellent and wide linear relationships from 0.06 to 1 μM and 1–4 μM respectively, with detection limits as low as 19.4 nM. With the increase of Cu2+/Hg2+ concentration, this nanohybrid probe also showed obvious fluorescence color changes that could be directly observed by the naked eye.

Sensitive and selective detection of Cu2+ and Pb2+ ions using Field Effect Transistor (FET) based on L-Cysteine anchored PEDOT:PSS/rGO composite

Herein, Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/reduced graphene oxide (rGO) (PEDOT:PSS/rGO) composite was prepared and further functionalized with L-Cysteine (LC) to manifest sensitive and selective detection of copper (Cu2+) and lead (Pb2+) ions using Field Effect Transistor (FET) in the concentration range of 1–60 µg/L. The sensor (PEDOT:PSS/rGO/L-Cysteine) exhibits low-voltage operations, highly sensitive and selective towards target metal ions (Cu2+ and Pb2+). The lower detection limits for Cu2+ and Pb2+ were found to be 0.33 µg/L and 2.36 µg/L, which is well below the World Health Organization WHO recommendations (2 mg/L (2 ppm) for Cu2+ ions and 10 µg/L (10 ppb) for Pb2+ ions.

Selective and simultaneous detection of cadmium, lead and copper by tapioca-derived carbon dot-modified electrode.

The need for the sensing of environmental pollutants cannot be overemphasized in the twenty-first century. Herein, a sensor has been developed for the sensitive and selective detection of copper (Cu2+), lead (Pb2+) and cadmium (Cd2+) as major heavy metals polluting water environment. A screen-printed carbon electrode (SPCE) modified by fluorescent carbon dots (CDs) and gold nanoparticles (AuNPs) was successfully fabricated for sensing Cu2+, Pb2+ and Cd2+. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were deployed for the analysis of ternary analytes. CV was set at a potential range of - 0.8 to + 0.2V at a scan rate of 100mV/s, and DPV at a potential range of - 0.8 to + 0.1V, scan rate of 50mV/s, pulse rate of 0.2V and pulse width of 50ms. DPV technique was applied through the modified electrode for sensitive and selective determination of Cu2+, Pb2+ and Cd2+ at a concentration range of 0.01 to 0.27ppm for Cu2+, Pb2+ and Cd2+. Tolerance for the highest possible concentration of foreign substances such as Mg2+, K+, Na+, NO3-, and SO42- was observed with a relative error less than ± 3%. The sensitivity of the modified electrode was at 0.17, 0.42 and 0.18ppm for Cd2+, Pb2+ and Cu2+, respectively, while the limits of detection (LOD) achieved for cadmium, lead and copper were 0.0028, 0.0042 and 0.014ppm, respectively. The quality of the modified electrode for sensing Cu2+, Pb2+ and Cd2+ at trace levels is in accordance with the World Health Organization (WHO) and Environmental Protection Agency (EPA) water regulation standard. The modified SPCE provides a cost-effective, dependable and stable means of detecting heavy metal ions (Cu2+, Pb2+ and Cd2+) in an aqueous solution. Graphical abstract .

ON–OFF Fluorescent Imidazole Derivative for Sensitive and Selective Detection of Copper(II) Ions

A novel multichromophoric hybrid compound, 2-[1-(4-tert-butylphenyl)-4,5-diphenyl-1H-imidazol-2-yl]-6-(pyren-1-yl)quinoline (TDIPQ) has been synthesized as an ON-OFF fluorescent chemosensor for copper(II) ions. Colorless TDIPQ in acetonitrile—water (2:1, v/v) selectively turns yellow along with fluorescence quenching upon addition of copper(II) ions. The fluorescence quenching is directly proportional to the concentration of copper(II) ions. The interaction between TDIPQ and copper(II) was investigated with the aid of UV-Vis, fluorescence, 1H NMR, and MALDI mass spectral techniques. The stoichiometry of the TDIPQ—Cu complex was determined to be 2:1 by Job’s Plot. Under similar experimental conditions, other competitive metal ions had negligible or no interference in the detection ability of TDIPQ. The detection and quantification limits of TDIPQ were estimated at 2 × 10−6 M and 6.2 × 10−6 M. respectively. This method showed an excellent precision of 0.98 ± 0.011 and recovery characteristic of 99.09±1.4%. It is applicable for the quantification of copper(II) in various samples such as drinking water, lab waste water, and soil. A mixture of TDIPQ with the BZA-Co-BZMA polymer can be cast as a film on a glass slide to be used as a sensor device to indicate the presence of copper. Polymer-coated TDIPQ chemosensing property was analyzed by SEM imaging.

Naked Eye and Selective Detection of Copper(II) in Mixed Aqueous Media Using a Cellulose-based Support

A new colorimetric sensor based-azo dye for Cu2+ detection was synthesized and characterized by FTIR and NMR spectroscopies. The results showed that the azo dye had a high selective and sensitive recognition toward Cu2+. The solution containing the sensor changed color from pink to pale yellow with a hypsochromic shift in the presence of Cu2+. The sensor selectivity and sensitivity toward Cu2+ ions were investigated by colorimetry and UV-Vis spectroscopy. For practical applications, a cellulosic textile test strip for high-selectivity detection of Cu2+ ions in aqueous solution was developed using the synthesized azo dye as chromogenic chemosensor molecule, while using a solid cellulose textile as a substrate. As a result, a spectacular color change of the test strip was observed depending on the amount of copper ions in contact with the strip, which allows an estimation of Cu2+ concentration by naked eye.

A Carbon‐Dot‐Based Fluorescent Probe for the Sensitive and Selective Detection of Copper(II) Ions

AbstractFluorescent carbon dots (CDs) are widely applied for the detection of heavy metal ions due to their nontoxicity, high sensitivity and stability. In this work, CDs were synthesized by a simple and green pyrolysis method without complicated post‐processing procedures and characterized by transmission electron microscope, X‐ray diffraction, fourier transform infrared spectroscopy, UV‐visible spectrophotometer and fluorescence spectroscopy. The CDs exhibited a relatively narrow size distribution of 3.5‐8.6 nm with an average size of 6.1 nm and their surface was decorated with abundant functional groups such as hydroxy and amino groups. They exhibited a strong fluorescent peak at 468 nm with a quantum yield of 25% under 365 nm UV irradiation. The CDs exhibited a strong fluorescence response to 70 μM Cu2+ with the sensitivity up to 77% due to the complexation between the amino groups decorated on the CD surface and the adsorbed copper ions. They also exhibited short response times of less than 1 min, high response selectivity and good stability.

Deciphering of Ligand‐to‐Metal Charge‐Transfer Process: Synthesis, Spectroscopic and Theoretical Study

AbstractMany reports on metal ion sensing applications are available in literature but the mechanism of selectivity is not clear. Here the synthesis and characterization of a Schiff base Furan‐2‐carboxylic acid pyren‐1‐ylmethylene‐hydrazide (PYFH) has been described with selective detection of copper(II) metal ion among different metal ions by UV–vis, fluorescence and HRMS spectroscopic methods. The S2− ion (Na2S) was added to the PYFH:Cu2+ complex for checking reversibility of PYFH by fluorescence, fluorescence microscopic imaging and molecular logic gate construction (combination of NOT and OR gate). From the experimental findings the reason for selectivity of Cu2+ metal ion among a series of metal ions is not clear. So, to explore the causes of selectivity of Cu2+ metal ion by PYFH, Density Functional Theory (DFT) calculation was conducted for free PYFH and various sets of metal ions individually with PYFH. From DFT calculation it was understandable that selectivity of PYFH towards Cu2+ ions occurred due to lowering of HOMO‐LUMO energy of PYFH:Cu2+ composites (‐8.46 & −5.80 eV) compared to free PYFH (‐5.56 & −2.15 eV). Whereas energy of HOMO and LUMO with other metals ions (PYFH:Mn+) are ∼‐5.50 and ∼‐2.24 eV respectively, as a result PYFH does not get any extra stability.

Facile Green Synthesis of Gold Nanoparticles with Carboxymethyl Gum Karaya, Selective and Sensitive Colorimetric Detection of Copper (II) Ions

Herein, we developed a gold nanoparticles (AuNPs) based label free colorimetric probe for the sensitive and selective detection of Copper (II) ions (Cu2+). Fabrication of the detection system involves a single step in which plant derived, nontoxic polysaccharide carboxymethyl gum karaya (CMGK) acts as reducing, stabilizing and functionalizing agent. Synthetic conditions were optimized by using UV–Vis spectra, zeta potential and DLS analysis and as synthesized AuNPs were thoroughly characterized by TEM, FTIR, and XRD analysis. They exhibited excellent stability to conditions like pH, salt and have a longer shelf life. These CMGK capped AuNPs exhibited a selective colorimetric response to Cu2+ ions with a visible colour change from red to blue, which could be due to the Cu2+ induced aggregation and the same was confirmed by TEM and DLS analysis. The detection conditions such as pH, amount of nanoparticles used and incubation time were optimized. Under the optimal detection conditions, the present system exhibited a good linear correlation (R2 = 0.998) in the range of 10–1000 nM of copper with a limit of detection 10 nM. Further the method was successfully applied for the detection of copper in real water samples and biological samples (human plasma and urine).

Graphene quantum dots decorated graphene as an enhanced sensing platform for sensitive and selective detection of copper(II)

In this paper, a simple and efficient electrochemical sensing platform was designed based on the hybrid of two carbon nanomaterials for the sensitive and selective detection of trace Cu(II) by using differential pulse anodic stripping voltammetry (DPASV) analysis. The GQDs/graphene/GCE exhibited enhanced electrochemical responses because of a fast electron transfer from graphene and a high affinity to Cu(II) from graphene quantum dots (GQDs). Under the optimal conditions, a good linear response in the range of 0.015–8.775μM with correlation coefficient of 0.9995 and a detection limit of 1.34nM (S/N=3) were obtained. The developed method was further validated and successfully applied to the detection of Cu(II) in real water samples. The simple preparation and efficient selectivity of the proposed modified electrode show the promising potential for applications in sensing of Cu(II).

A New Carbazole-Based Fluorescence Sensor for High Selective Detection of Copper(II) in Aqueous Solutions

A New Carbazole-Based Fluorescence Sensor for High Selective Detection of Copper(II) in Aqueous Solutions

Cyclam-functionalized carbon dots sensor for sensitive and selective detection of copper(II) ion and sulfide anion in aqueous media and its imaging in live cells

The detection of copper ion (Cu2+) and sulfide anion (S2−) is of vital importance since the abnormal level of Cu2+ or S2− can lead to many diseases. Herein, a highly sensitive and selective fluorescent sensor, 1,4,8,11-tetraazacyclotetradecane (Cyclam)-functionalized carbon dots (CCDs), has been designed, synthesized and evaluated for Cu2+ and S2−. For this nanoprobe, a specific fluorescence resonance energy transfer (FRET) process can be effectively take place between carbon dots and the surface Cu2+-Cyclam complex, the as-prepared CCDs display high sensitivity (detection limit: 100nM) and selectivity toward Cu2+ among many other metal cations (such as Mg2+, Co2+, Pb2+, Ni2+, Mn2+, Hg2+, Fe2+, Ca2+ and Zn2+) in 100% aqueous solution. Moreover, it is worth to point out that the subsequent addition of S2− can extract Cu2+ from the CCDs-Cu2+ complex and recover the fluorescence of carbon dots, the detection limit for S2− can reach to 130nM in the aqueous medium. And no statistically significant interference was observed among the other 10 anions (HCO3−, SO42−, NO3−, Cl−, CO32−, S2O32−, F−, Br−, HPO4−, ClO4−) for S2− through the study. In addition, the novel type of multifunctional fluorescent sensor has a relatively wide pH range (pH 4–10). At the same time, it exhibited remarkable longterm fluorescence stability (≥35 days) for Cu2+ detection. In addition, this nanoprobe exhibits very low cytotoxicity and can easily permeate the cell membrane and realize Cu2+ and S2− monitoring and imaging in live cells. Therefore, this novel approach can be used in various fields, such as the detection of multiplex analytes in biological applications and environment, and it will reveal great application prospects.

Immobilization of gold nanoclusters inside porous electrospun fibers for selective detection of Cu(II): A strategic approach to shielding pristine performance.

Here, a distinct demonstration of highly sensitive and selective detection of copper (Cu2+) in a vastly porous cellulose acetate fibers (pCAF) has been carried out using dithiothreitol capped gold nanocluster (DTT.AuNC) as fluorescent probe. A careful optimization of all potential factors affecting the performance of the probe for effective detection of Cu2+ were studied and the resultant sensor strip exhibiting unique features including high stability, retained parent fluorescence nature and reproducibility. The visual colorimetric detection of Cu2+ in water, presenting the selective sensing performance towards Cu2+ ions over Zn2+, Cd2+ and Hg2+ under UV light in naked eye, contrast to other metal ions that didn’t significantly produce such a change. The comparative sensing performance of DTT.AuNC@pCAF, keeping the nonporous CA fiber (DTT.AuNC@nCAF) as a support matrix has been demonstrated. The resulting weak response of DTT.AuNC@nCAF denotes the lack of ligand protection leading to the poor coordination ability with Cu2+. The determined detection limit (50 ppb) is far lower than the maximum level of Cu2+ in drinking water (1.3 ppm) set by U.S. Environmental Protection Agency (EPA). An interesting find from this study has been the specific oxidation nature between Cu2+ and DTT.AuNC, offering solid evidence for selective sensors.

Lanthanide Luminescence Modulation by Cation–π Interaction in a Bioinspired Scaffold: Selective Detection of Copper(I)

AbstractA prototype luminescent turn‐on probe for Cu+ (and Ag+) is described, harnessing a selective binding site (log Kass=9.4 and 7.3 for Cu+ and Ag+, respectively) based on the coordinating environment of the bacterial metallo‐chaperone CusF, integrated with a terbium‐ion‐signaling moiety. Cation–π interactions were shown to enhance tryptophan triplet population, which subsequently sensitized, on the microsecond timescale, the long‐lived terbium emission, offering a novel approach in bioinspired chemosensor design.

Lanthanide Luminescence Modulation by Cation-π Interaction in a Bioinspired Scaffold: Selective Detection of Copper(I).

A prototype luminescent turn-on probe for Cu(+) (and Ag(+)) is described, harnessing a selective binding site (log Kass = 9.4 and 7.3 for Cu(+) and Ag(+), respectively) based on the coordinating environment of the bacterial metallo-chaperone CusF, integrated with a terbium-ion-signaling moiety. Cation-π interactions were shown to enhance tryptophan triplet population, which subsequently sensitized, on the microsecond timescale, the long-lived terbium emission, offering a novel approach in bioinspired chemosensor design.