Colorimetric Detection Of Cu2 Research Articles

Fabrication of Paper-Based Silver Nanoparticle (AgNP) Sensors for Smartphone-Based Colorimetric Detection of Cu (II) in Water

Detection of heavy metals in water has long been a key area of study due to the adverse health effects these substances may bring. Multiple methods of detecting heavy metals have already been established. Though these methods are highly selective and can detect heavy metals in trace amounts, they commonly require specialized equipment. Thus, producing an inexpensive, reliable, and convenient sensor that could be used for point-of-need applications is of great interest. This study focuses on fabricating paper-based silver nanoparticle (AgNP) sensors for the smartphone-based colorimetric detection of Cu2+ ions in water. Polymer-decorated AgNPs functionalized by chitosan, glutaraldehyde, and polyethyleneimine were used as the main sensing mechanism for the paper-based sensors. Various fabrication methods were tested, and the optimal fabrication method was through the rectangular soak method with a total of 5 coatings as it produced the most uniform sensors. The calibration curve was studied over concentrations from 0.5 mM to 50 mM of Cu2+ across multiple parameters. It was found that there was a linear correlation between the Euclidean distance measured in reference to the blank filter paper against the concentration of copper in the analyte. The calibration curve exhibited a dynamic linear range between 2 mM to 28 mM of Cu2+ with R2 = 0.99789. The LOD and LOQ were reported at 94.9438 ppm and 316.4793 ppm, respectively. Lastly, selectivity studies were also performed to determine the sensor’s response to other metal ions. It was found that the response of the sensor to Cu2+ was significantly different from those elicited by Ni2+, Cd+, Mn2+, Ca2+, Mg2+, Sn2+, K+, Cr3+, Al3+, Ba2+, Na+, Zn2+, Fe3+, and Fe2+. The study demonstrated its strong potential as rapid on-site detection method for Cu (II) in industrial wastewater.

Colorimetric Detection of Cu2+ and Ag+ Ions Using Multi-Responsive Schiff Base Chemosensor: A Versatile Approach for Environmental Monitoring.

In this study, we have synthesized a novel Schiff base-centered chemosensor, designated as SB, with the chemical name ((E)-1-(((6-methylbenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol). This chemosensor was structurally characterized by FT-IR, 1H NMR, UV-Vis and fluorescence spectroscopy. After structural characterization the chemosensor SB was subsequently employed for the detection of Cu2+ and Ag+, using fluorescence spectroscopy. The chemosensor SB showed excellent ability to recognize the target metal ions, leading to fluorescence enhancement and color change from yellow to yellowish orange for Cu2+ and yellow to radish for Ag+ ions. The detection capabilities of this chemosensor were impressive, showing excellent selectivity and an exceptionally low detection limit of 0.0016 µM for Cu2+ and 0.00389 µM for Ag+. Most notably, our approach enables the quantitative detection both metal ions in different water and soil samples at trace level. This achievement holds great promise for analytical applications and offers significant contributions to the field of chemical sensing and environmental protection.

A highly selective 2-hydroxybenzhydrazone based dual sensor for Cu2+ and Fe2+ ions: Spectroscopic, computational, cell imaging studies and logic gate construction

2-Hydroxybenzhydrazone based probe HNN demonstrated highly selective sensing ability towards Cu2+ and Fe2+ ion through colorimetric and fluorimetric methods respectively. The probe can be used as a “naked-eye” sensor based on its color change from almost colorless to bright yellow (for Cu2+) and pale yellow (for Fe2+). The colorimetric detection of Cu2+ involved enhancement in internal charge transfer (ICT). In the detection of Fe2+ through fluorescence, combined effect of restricted photo-induced electron transfer (PET) and paramagnetic nature of Fe2+ played major role. Job's plots based on absorption (Cu2+) and fluorescence (Fe2+) data along with mass spectral studies indicated 1:1 stoichiometry of metal to HNN in the complex. The binding of the probe HNN with both the metal ions was found chemically reversible by adding EDTA. Experimental observations on binding of the probe with metal ions were corroborated with density functional theory (DFT). The effect of pH and response time in sensing was also determined. The probe was found useful for in vivo detection and imaging of Fe2+ in MDA-MB-231 cells. Paper strips of the probe were made and used for naked-eye detection of Cu2+. The probe was also used in the construction of logic gate for detection of Cu2+and Fe2+.

Azophenyl appended Schiff base probe for colorimetric detection of Cu2+ in semi‐aqueous medium and live cell imaging

AbstractA phenylazo appended ortho‐vanillin Schiff base scaffold (HAZ) has been used for selective colorimetric sensing of Cu2+ in semi‐aqueous medium (methanol–water, 1:1, v/v) in the presence of 16 cations and 20 anions, and the limit of detection is 1.8 × 10−7 M. The structures of HAZ and Cu (II) complex, [Cu(AZ)2], have been characterised by spectroscopic data (UV–Vis, Fourier transform infrared and electron paramagnetic resonance) and established by the single crystal X‐ray diffraction measurement. The Job's plot from the absorption studies has also confirmed the 1:2 stoichiometry of Cu2+:HAZ. The absorption spectrum of [Cu (AZ)2] has returned to the spectrum of HAZ on the addition of Na2EDTA solution which is again recovered upon the addition of Cu2+ solution. Discrete Fourier transform computations were carried out using the coordinates of the X‐ray structures of the compounds, and the molecular functions were used to correlate the solution spectroscopic properties. In addition to this, the probe is treated on MDA‐MB 231 breast cancer cells to check the cytotoxicity. The probe is used for the detection of trace quantity of Cu2+ in the cancer cell.

Highly Selective Colorimetric Detection of Cu2+ Using EDTA-Complexed Chlorophyll-Copper/ZnO Nanorods with Cavities Specific to Cu2+ as a Light-Activated Nanozyme.

In this study, chlorophyll-copper (ChlCu)-modified ZnO nanorods (ChlCu/ZnO) were prepared, and then sodium ethylenediamine tetraacetate (EDTA) was used to remove part of Cu2+ in ChlCu, leaving cavities with specific adsorption activity for Cu2+ in E-ChlCu/ZnO. Appropriate EDTA treatment improved the photoactivity of ChlCu/ZnO and the adsorption selectivity to Cu2+. However, excessive EDTA treatment might lead to the collapse of the ChlCu structure, resulting in a decrease in photoactivity. The E-ChlCu/ZnO sample with 8 h of ChlCu treatment and 2 h of EDTA treatment showed optimal photoactivity. The as-prepared E-ChlCu/ZnO exhibited activity as a light-activated nanozyme, which could oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to blue under illumination, but when Cu2+ was present in the solution, this colorimetric reaction was inhibited; therefore, E-ChlCu/ZnO could be used for colorimetric detection of Cu2+. Because of the existence of specific cavities, E-ChlCu/ZnO showed excellent detection selectivity, a wide linear detection range (0-1 and 1-15 μM), and a low detection limit (0.024 μM) in the colorimetric detection of Cu2+.

Spirooxazine-Based Dual-Sensing Probe for Colorimetric Detection of Cu2+ and Fe3+ and Its Application in Drinking Water and Rice Quality Monitoring.

A spirooxazine derivative, PheSPO (3,3-dimethyl-1-phenethylspiro[indoline-2,3′-naphtho[2,1-b][1,4]oxazine]), as a dual-sensing probe for Cu2+ and Fe3+ was synthesized, and its structure was confirmed by 1H NMR, 13C NMR, HRMS, and single-crystal X-ray diffraction. The results reveal that the PheSPO probe is selective to both Cu2+ and Fe3+ through distinct colorimetric responses in acetonitrile. The sensing performance of PheSPO toward Cu2+ was investigated, and upon addition of Cu2+, an instant change in color from colorless to bright yellow with a strong absorption band at 467 nm was observed. Due to a dual-sensing behavior, PheSPO also exhibits a unique response toward Fe3+ that can be discovered from a color change from colorless to red at an absorption wavelength of 514 nm. Based on spectroscopic analyses and density functional theory calculations, the 1:1 stoichiometric complexation of PheSPO with the targeted metal ions was proposed and the binding constants of 1.95 × 103 M–1 for Cu2+ and 1.29 × 103 M–1 for Fe3+ were obtained. In addition, the detection limits of PheSPO for Cu2+ and Fe3+ were 0.94 and 2.01 μM, respectively. To verify its applicability in real samples, PheSPO was further explored for quantitative determination of both Cu2+ and Fe3+ in spiked drinking water. The results showed that the recoveries of Cu2+ and Fe3+ examined using the PheSPO probe were found comparable to those obtained from atomic absorption spectroscopy. Moreover, the PheSPO strip test was developed, and its utilization for qualitative detection of Fe3+ in real rice samples was demonstrated.

Development of 2-hydroxy-naphthaldehyde functionalized Schiff base chemosensor for spectroscopic and colorimetric detection of Cu2+ and Pd2+ ions

The colorimetric detection of metal ions is significantly applied for industrial, ecological, and medical applications. Here, we synthesize 4-((Z)-1-(((Z)-(2-hydroxynaphthalen-1-yl)methylene)-hydrazineylidene)ethyl)benzene-1,3-diol a new chemosensor that acts for sensitive and selective detection of Cu2+ and Pd2+ ions to the ligand. The recognition is determined by redshift in UV–visible, emission intensity changes in fluorescence, colorless to yellow coloration, and cyclic voltammetric signal changes with the addition of Cu2+ and Pd2+ ions to the ligand. The insights into the color changes are described visually and under different wavelengths of light. The designed colorimetric sensing model is developed as paper, cotton, and mask-based assay for Pd2+ and Cu2+ ion. The chemosensor reversibility is checked with the addition of ethylenediaminetetraacetic acid (EDTA), and color changes are observed with naked eyes. The infrared (IR) spectral analysis describes ligand's binding behavior towards selective metal ions. In addition, the chemosensor works for low detection limit (4.906 × 10-7 M for Cu2+, 9.802 × 10-7 M for Pd2+), limit of quantitation (1.636 × 10-6 M for Cu2+, 3.267 × 10-6 M for Pd2+) with good association affinity (1.273 × 105 M−1 for HMHEB-Cu2+ binding, 6.983 × 1010 M−2 for HMHEB-Pd2+ binding).

Development of 2-Hydroxy-Naphthaldehyde Functionalized Schiff Base Chemosensor for Spectroscopic and Colorimetric Detection of Cu2+ and Pd2+ Ions

Development of 2-Hydroxy-Naphthaldehyde Functionalized Schiff Base Chemosensor for Spectroscopic and Colorimetric Detection of Cu2+ and Pd2+ Ions

Colorimetric detection of Cu2+ by amino phenol based chemosensor

A colorimetric chemosensor, based on 2-amino phenol Schiff base has been successfully synthesized by simple condensation reaction of 2-amino quinoline 3-carbaldehyde and 2-amino phenol. Synthesized Schiff base ligand 2-(2-aminoquinolin-3-yl methyleneamino) phenol (SBL) was characterised by various spectroscopic techniques. SBL displayed highly selective and sensitive Colorimetric enhancement to Cu2+ ion over 13 competing ions in ethanol–water (99:1/v:v) solution. UV titration experiment showed that SBL exclusively reacted with Cu2+ and the stoichiometric ratio is 1:1. The detection limit of SBL-Cu2+ was estimated to be 4.3 nM and 8.2 × 10–8 M, respectively.

Optical detection of Al(III) and Cu(II) ions in an aqueous medium by using a simple probe possessing O,O-donor moiety

A commercially available probe (RS) has been reported for instantaneous selective colorimetric detection of Cu(II) and fluorescent detection of Al(III) ions in H2O:DMSO (90:10% v/v) medium. The probe displays a color change from pale yellow (λab 352 nm) to yellowish-green (λab 411 nm) with Cu(II) and a change in emission from green (λex 340 nm; λem 522 nm) to bluish-green (λem 489 nm) with Al(III) ions. The optical detection of these metal ions by RS is via the formation of tetragonally distorted octahedral RS-Cu(II) and tetrahedral RS-Al(III) complexes as evidenced from the results of UV-Vis, 27Al & 1H NMR, HRMS, EPR and thermal analysis studies. Job’s method indicates that the stoichiometry of both these complexes is 1:1. The probe's corresponding optical changes are particular for Cu(II) and Al(III) ions in the presence of other metal ions. RS displays high selectivity to these ions in a wide pH range. The limits of the detection of Cu(II) and Al(III) are as low as 66 nM and 0.83 µM, respectively. Further, RS could be applied as a fluorescent probe for observing Al(III) ions in living HeLa cells by carrying out cell image studies.

Colorimetric detection of Cu2+ using of a mixture of ponceau 6R and a cationic polyelectrolyte in aqueous solution

A colorimetric chemosensor is reported for Cu2+ by a simple mixture of two commercially available reagents, ponceau 6R (P6R) and poly(diallyldimethylammonium chloride) (PDADMAC) in an aqueous solution. P6R interacted electrostatically with PDADMAC to form the self-aggregate of P6R and exhibit a different sensing capability from P6R alone. The mixture showed high sensitivity and specific selectivity for detection of Cu2+ compared with various physiological and environmentally important metal ions. The addition of Cu2+ caused a hypsochromic shift with a distinct color change from red to yellow. While, upon adding Cu2+ to P6R alone, the solution underwent no distinct color change. The binding mode of P6R with Cu2+ was determined to be a 2:1 stoichiometry from Job plot and Cu2+ titration experiments. The results provide an easy method for developing new colorimetric sensors for metal ions by a combination of anionic dyes and cationic polyelectrolytes.

Selective colorimetric detection of copper (II) by a protein-based nanoprobe

In this work, we report a novel protein-based nanoprobe (PNP) that can be employed for quantitative analysis of Cu2+ in pure water medium and real samples. Structurally, the proposed nanoprobe comprises a biofriendly protein (hen egg-white lysozyme (HEWL)) and a Cu2+-specific chromogenic agent, where HEWL acts as a nanocarrier encapsulating a structurally tailored rhodamine B derivate. The resulting PNP exhibits a hydrodynamic diameter of ~ 106 nm and efficiently disperses in water, enabling the detection of Cu2+ in pure aqueous systems without the aid of any organic co-solvents. The high sensitivity and selectivity of PNP allow the colorimetric detection of Cu2+ in the presence of other metal interferents with a low detection limit of 160 nM. The satisfying recovery of trace level Cu2+ in environmental samples demonstrate the great potential of employing PNP for the determination of Cu2+ in actual applications. Most importantly, the simple co-grinding method employing proteins and chromogenic agents provides a novel strategy to generate sensing systems that are useful detection of pollutants in aqueous samples.

Sensitive and selective colorimetric detection of Cu (II) in water samples by thiazolylazopyrimidine-functionalized TiO2 nanoparticles.

In this study, a new thiazolylazopyrimidine-functionalized TiO2 nanosensor (TiO2-TAP) has been developed for sensitive and selective colorimetric detection of Cu2+ in water samples. Thiazolylazopyrimidine (TAP) as an azo ligand and TiO2-TAP as highly selective nanosensor were successfully prepared through the diazo coupling reaction and surface chemical modification, respectively. Characterization of TiO2-TAP NPs using Fourier transmission infrared (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X- ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis revealed that the TiO2 NPs were effectively modified with the synthesized epoxy-activated thiazolylazopyrimidine. The synthesized azo ligand containing azo chromophore (N=N) produce color and make a stable complex formation with Cu2+ based on charge-transfer transduction in the detection system. The color change of TiO2-TAP solution from yellow to red occur directly after few seconds of addition of Cu2+ ions, as a result of surface complexation. The TiO2-TAP has revealed high affinity, sensitivity and selectivity for copper ion over other competing metal ions in aqueous media. The experimental data revealed that the Cu2+ ions was sensed and adsorbed by the TiO2-TAP at optimal pH5.0. The results also confirmed that the TiO2-TAP has a wide linear detection range for Cu2+ (0.01 to 12.5μM). From UV-vis titration experiment, the limit of detection (LOD) for Cu2+ ions was found to be 2.51nM. The proposed method was successfully applied for the sensitive and selective detection of Cu2+ in tap water, sea water and well water. In addition, Cu2+ recovery improved using the TiO2-TAP containing N, S and O atoms as chelating sites. Therefore, the developed nanosensor with great features like the cost-effective, excellent sensitively and selectively, short response times and high adsorption efficiency for Cu2+ can be utilized in any physical and biological conditions.

Novel phenothiazine-based fast-responsive colori/fluorimetric sensor for highly sensitive, selective and reversible detection of Cu2+ in real water samples and its application as an efficient solid-state sensor

A novel highly sensitive and selective phenothiazine-based sensor PN has been successfully synthesized. The sensor PN showed specific recognition towards Cu2+ through dual “naked-eye” colorimetric and “turn-off” fluorescence responses in DMSO/H2O (1:3, V/V) solution with ultrafast response and good reversibility. The detection limit was determined to be as low as 0.179 µM, which was much lower than drinking water permission concentration by the United States Environmental Protection Agency (～20 µM) and the World Health Organization (～30 µM). The 1:1 binding mechanism of PN with Cu2+ was proposed and well confirmed by fluorescence titration, Job’s plot, 1H NMR, HRMS, FTIR analysis and DFT studies. Moreover, the sensor PN was successfully applied to sensitively detect the Cu2+ ions in real water samples with good accuracy and high precision. Furthermore, sensor PN could serve as a cost-effective solid-state sensor for immediate, convenient and “naked-eye” colorimetric detection of Cu2+ in environmental samples.

A dual‐function chemosensor based on coumarin for fluorescent turn‐on recognition of Hg2+ and colorimetric detection of Cu2+ in aqueous media

A novel coumarin derivative CTT was synthesized via the condensation of 7‐(N,N‐diethylamino) coumarin‐3‐aldehyde with 5‐amino‐1,3,4‐thiadiazole‐2‐thiol and its structure was characterized using infrared spectroscopy (IR), 1H NMR, mass spectrometry (MS) techniques, and elemental analysis. The recognition properties of CTT with metal ions were investigated in CH3CN–H2O (v/v = 1/1) solution using UV–vis absorption and fluorescence emission spectrum method. The results showed that CTT could monitor Cu2+ and Hg2+ simultaneously as a dual‐function chemosensor in CH3CN–H2O (v/v = 1/1). CTT could be used to detect Cu2+ colorimetrically; when using CTT, a color change from yellowish‐brown to yellowish‐green could be readily observed by the naked eye. CTT showed turn‐on fluorescent recognition of Hg2+, the fluorescence enhancement was attributed to the inhibited C=N isomerization and the obstructed excited state intramolecular proton transfer (ESIPT) of CTT. The recognition mechanism of CTT for Cu2+ and Hg2+ was studied by experiments and theoretical calculations, respectively. Therefore, CTT has the ability to be a “single chemosensor for dual targets.”

A dual-mode highly selective and sensitive Schiff base chemosensor for fluorescent colorimetric detection of Ni2+ and colorimetric detection of Cu2.

In this paper, a novel flexible Schiff base chemosensor N'-(2-hydroxy-3-methoxybenzylidene)-2-(benzamido)benzohydrazide (L) has been designed, synthesised and characterised by 1H-NMR, IR spectroscopy, ESI-MS spectrometry and single crystal XRD analysis. A significant fluorescence enhancement of L was observed only in the presence of Ni2+ ions with a detection limit of 3.64 μM whereas Cu2+ induced fluorescence quenching, although both the metals showed colorimetric responses in methanol-Tris-HCl buffer (10 mM, pH 7.2) solution (1 : 1, v/v). The single crystal structure of L-Cu2+ has also been determined. No major interference by the other effective background cations (Fe3+, Fe2+, Co2+, Zn2+, Cd2+, Hg2+, Pb2+, Cr3+, Ag+, Al3+ and Mn2+) was observed even at a higher concentration of analytes. The experimental results were further supported by DFT studies. The chemosensor L can be applied to the formation of binary logical devices, recovery of contaminated water samples and living intracellular media.

A novel rhodamine-based turn-on probe for fluorescent detection of Au3+ and colorimetric detection of Cu2+

In this work, we design and synthesize the novel probe RC through introduction the 1-aza-4,13-dithia-15-crown-5 ring into the structure of rhodamine 6G hydrazide, where the N atom of crown ring is responsible for quenching of rhodamine fluorescence. The compound obtained behaves as multifunctional cation sensor providing selective fluorescent response to Au3+ and selective colorimetric response to Cu2+ ions in aqueous acetonitrile (1/1, v/v) at pH 7.0. The use of 10−5 M RC solution allowed reliable determination of target cations in the presence of a wide range of environmentally relevant ions with detection limits of 2 × 10−6 M and 5 × 10−7 M for gold and copper, respectively.

A solvent-dependent chemosensor for fluorimetric detection of Hg2+ and colorimetric detection of Cu2+ based on a new diarylethene with a rhodamine B unit.

A novel solvent-dependent chemosensor 1o based on a diarylethene containing a rhodamine B unit has been designed. It could be used as a dual-functional chemosensor for selective detection of Hg2+ and Cu2+ by monitoring the changes in the fluorescence and UV-vis spectral in different solvents. A striking fluorescence enhancement at 617 nm was observed in DMSO upon the addition of Hg2+. However, 1o showed a remarkable absorption band appeared with maximum absorption at 555 nm after the addition of Cu2+ in THF. The results of ESI-MS spectra and Job's plot confirmed a 1 : 1 binding stoichiometry between 1o and the two ions. The limits of detection of Hg2+ and Cu2+ were determined to be 0.14 μM and 0.51 μM, respectively. A 1 : 2 demultiplexer circuit was constructed by using UV light as data input, Cu2+ as the address input, and the absorbance at 555 nm and the absorbance ratio of (A603/A274) as the dual data outputs.

Dual-emissive fluorescent probe based on phenolphthalein appended diaminomaleonitrile for Al3+ and the colorimetric recognition of Cu2+

A novel dual emissive fluorescent probe was designed and synthesized by linking phenolphthalein and diaminomaleonitrile units. The present probe (PDM) can be used not only for fluorogenic detection of Al3+ by way of the excited enol-keto forms but also colorimetric detection of Cu2+. PDM probe showed a selective fluorescence enhancement with dual channel emissions for Al3+ in a mixture of EtOH/H2O (9/1). 1H NMR and DFT methods were also carried out to support the complexation between PDM and Al3+ ion. In addition, PDM presented highly selective colorimetric response for Cu2+ over other metal ions. The reversibility of PDM-Al3+ and PDM-Cu2+ complexes was successively established with the addition of TBAF and EDTA, respectively. The detection limits were determined to be 92.0 nM for Al3+ and 2.81 μM for Cu2+. The obtained results revealed that the designed PDM probe could be suitable for monitoring Al3+ under UV lamp and Cu2+ in water samples with the naked eye, which was rapid, convenient, low-cost and environmental friendly.

A diarylethene based multi-functional sensor for fluorescent detection of Cd2+ and colorimetric detection of Cu2+

A diarylethene based multi-functional sensor has been designed and synthesized. It not only exhibited excellent photochromism, but also has recognition performance for Cd2+ and Cu2+. Upon addition of 7.0 equiv. Cd2+, its emission intensity enhanced 106-fold, and the fluorescent color changed from dark to blue. Meanwhile, it also displayed colorimetric sensing ability to Cu2+ with the solution color changed from colorless to yellow, that could be observed by the naked eyes. The 1: 1 stoichiometry between the sensor and the two ions was verified by Job's plot and MS. The LOD for Cd2+ and Cu2+ was determined to be 1.89 × 10−7 mol L−1 and 4.12 × 10−8 mol L−1, respectively. Furthermore, the sensor was successfully applied in the detection of Cd2+ and Cu2+ in practical samples.