A dual chemosensor for Cu2+ and Fe3+ based on π-extend tetrathiafulvalene derivative

A new dual chemosensor (TTF-PBA) for Fe³⁺ and Cu²⁺ in different signal pathways was designed and synthesized. The absorption spectrum, fluorescence spectrum and cyclic voltammograms changed in the presence of Cu²⁺ and Fe³⁺. The optical color changed within 5 s from yellow to orange upon the addition of Cu²⁺, and it changed to dark yellow when Fe³⁺ existed. The cyclic voltammogram of Cu²⁺/TTF-PBA changed from E_ox = 0.50 V, E_red = 0.32 V to E_ox = 0.64 V, E_red = 0.80 V (vs Ag/AgCl) upon the addition of 2.0 equiv. Cu²⁺. As for Fe³⁺/TTF-PBA, its oxidation wave disappeared, and its reduction wave appeared at E_red = ?0.59 V (vs Ag/AgCl) upon the addition of 4.0 equv. Fe³⁺. The sensor displayed high selectivity for Cu²⁺ and Fe³⁺ over other ions including Pb²⁺, Zn²⁺, Ni²⁺, Ag⁺, Cr³⁺, Mn²⁺, Al³⁺, Co²⁺, Pd²⁺, Hg²⁺, Fe^2+, Cd²⁺, Ce³⁺, Bi³⁺ and Au³⁺, the detection limits for Cu²⁺ and Fe³⁺ ion reached as low as 5.33 × 10^?7 mol/L and 5.34 × 10^?7 mol/L, respectively. Furthermore, when Fe³⁺ existed, Cu²⁺ can be detected sequentially by the sensor through the absorption spectrum and the color change observed by naked-eyes.     

Thermal and ion-exchange studies on chelating terpolymer resins derived from o cresol urea formaldehyde

Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths.     

Applications of Macrocyclic Polyethers in Analytical Sensors and Ion Separation

Artificial macrocyclic polyethers were synthesized and applied as neutral carriers for ion-selective PVC membrane electrodes, ion-chromatographic packing materials, extractants and adsorbents for ion separation, coating materials for piezoeletrical membrane sensors for organic species, and ion-transport carriers through liquid membranes. Ion-selective electrodes such as those for K⁺ Na⁺, UO₂²⁺, Cs⁺, Pb²⁺, Fe³⁺, Hg²⁺ and Ag⁺ ions based on crown ether-phosphotungstic acid (PW) precipitates and dithio crown ethers respectively were prepared and showed good sensitivity and selectivity. Crown ether-PW precipitates were applied as adsorbents of rare-earth ions and some common heavy-metal ions. Some rare-earth ions were easily extracted with crown ethers, especially 15-crown-5. Poly(stytene/divinyl benzene) cryptand-22 resin was synthesized and applied as a bifunctional stationary phase of ion chromatography to separate bom cations and anions, even some organic carboxylate geometric isomers. Crown ethers such as mono-benzo-15-crown-5 was successfully applied as a coating material on piezoelectric quartz membrane sensors for some organic species. The oscillation frequency of the crown-ether quartz-membrane sensor was sensitive to organic vapours such as amines and alcohols. Upon adsorption of organic species on the crown-ether quartz membrane, the oscillation frequency of the sensor decreased obviously. Special crown ether such as dibenzo-16-crown-5-oxyacetic acid, decyl-cryptand-22 and 1, 4-dihydro-pyridine-18-crown-5 were synthesized and successfully applied as ion-transport carriers (ionophores) for transport of Na⁺ K⁺ and Mg²⁺ ions through liquid membranes.     

Accumulation and stripping behavior of silver ions at dl-dithiothreitol self-assembled monolayer modified gold electrodes

Silver ions can be entrapped at the dl-dithiothreitol (HSCH₂(CHOH)₂CH₂SH, DTT) self-assembled monolayer films modified gold electrodes. When the potential was made moving, an anodic peak was observed at about 0.23 V (vs. SCE). When the electrode Au/DTT was modified with dodecyl mercaptan further, more Ag (I) can be accumulated and the peak grows. Conditions, such as solution pH and supporting electrolyte, were optimized for Ag (I) determination. Under the selected conditions, i.e. 0.010 M pH 4.3 potassium hydrogen phthalate, preconcentration time of 5 min at open circuit, the anodic peak height is linear to the concentration of Ag (I) in the small range of 0.6-2.4 μM. The influence of some ions on the determination of Ag (I) was examined. The Br⁻ ion makes the peak decrease and NCS⁻ makes the peak increase. But the determination is not interfered by 1000-fold Pb²⁺, Cd²⁺, Hg²⁺, Fe³⁺, Ni²⁺, Co²⁺, Cu²⁺ and Sn²⁺ when EDTA was added into the solution. The mechanism involved was discussed.     

Silver(I)‐Selective PVC Membrane Potentiometric Sensor Based on a Recently Synthesized Calix[4]arene

A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dihydroxy‐calix[4]arene‐thiacrown‐4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10^?2?1.0×10^?6 M) with a slope of 53.8±1.6 mV per decade. It has a relatively fast response time (5–10 s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag⁺ ions over Pb²⁺, Cd²⁺, Co²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Sr²⁺, Mg²⁺, Ca²⁺, Li⁺, K⁺, Na⁺, NH₄⁺ ions and can be used in a pH range of 2–6. Only interference of Hg²⁺ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions.     

A Bis‐Oxime Derivative of Diaza‐18‐Crown‐6 as an Ionophore for Silver Ion

A new pendant‐arm derivative of diaza‐18‐crown‐6, containing two oxime donor groups, has been synthesized and incorporated into a polyvinyl chloride (PVC) membrane ion‐selective electrode. The electrode shows selectivity for Ag⁺ ion, with a near Nernstian response. Pb²⁺, Cu²⁺, Hg²⁺, and Tl⁺ are major interfering ions, with Cd²⁺ having minor interference. The electrode shows no potentiometric response for the ions Mg²⁺, Al³⁺, K⁺, Ca²⁺, Ni²⁺, Fe³⁺, and La³⁺, and is responsive to H⁺ at pH<6.     

A pyrene-based dual chemosensor for colorimetric detection of Cu2+ and fluorescent detection of Fe3+

A pyrene based chemosensor was designed and synthesized. The pyrene fluorophore was connected with a pyridine unit through a Schiff base structure to give the sensor (L). L was tested with a variety of metal ions and exhibited high colorimetric selectivities for Cu²⁺ and Fe³⁺ over other ions. Upon binding with Cu²⁺ or Fe³⁺, L showed an obvious optical color change from colorless to pink for Cu²⁺ or orange for Fe³⁺ over a wide pH range from 3 to 12. Moreover, the fluorescence of L at 370 nm decreased sharply after bonding with Fe³⁺, while other metal ions including Cu²⁺ had no apparent interference. Thus, using such single chemosensor, Cu²⁺ and Fe³⁺ can be detected independently with high selectivity and sensitivity. The limits of detection toward Cu²⁺ and Fe³⁺ were 8.5 and 2.0 μM, respectively. DFT calculation results also proved the formation of stable coordination complexes and the phenomenon of fluorescence quenching by Fe³⁺. Furthermore, L was also successfully used as a bioimaging reagent for detection of Fe³⁺ in living cells.     

A Coated Graphite Thorium‐Ion Selective Potentiometric Sensor Based on a Calix[4]arene Bearing Phosphoryl Groups

5,11,17,23‐Tetra‐tert‐butyl‐25,26,27,28‐tetrakis(diphenylphosphinoylmethoxy)calix[4]arene ( 1 )has been used for the preparation of a graphite coated thorium ion‐selective electrode (Th⁴⁺‐ISE). The plasticized PVC membrane containing 30% PVC, 58% ortho‐nitrophenyloctylether (NPOE), 4% sodium tetraphenylborate (NaTPB) and 8% ionophore was directly coated on a graphite rod. This sensor gave good Nernstian responses with a slope of 15.5 ± 0.1 mV/decade over a concentration range of 1 × 10^?5 ?1 × 10^?3 M of thorium ions with a limit of detection of 7.9 × 10^?6 M. The dynamic response time of the electrode to achieve a steady potential was found to be about 15 seconds. The potential of the prepared sensor was independent of the pH variation in the range 2.3–4.0. The selectivity relative to several mono‐, di‐ and tri‐valent metal ions, i.e. Li⁺, Na⁺, K⁺, Ag⁺, NH₄⁺, Sr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, La³⁺, Sm³⁺, Dy³⁺, Er³⁺ and Y³⁺ was examined. This electrode can be used for 6 months without any considerable divergences in the potential response. The sensor was successfully used as an indicator electrode for the potentiometric titration of a thorium solution using a standard solution of EDTA.     

Determination of copper ion by square wave anodic stripping voltammetry at antimony trioxide-modified carbon nanotube paste electrode

In this work, an antimony trioxide-modified multi-walled carbon nanotube paste electrode (Sb₂O₃/CNTPE) was employed for determination of Cu²⁺ ions by using square wave anodic stripping voltammetry (SWASV) in the presence of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) as a chelating agent. The field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS) methods were applied to estimate the morphology and properties of the modified electrode. Measurements related to SWASV were taken in 0.6 M HCl at ?1.0 V versus Ag|AgCl|KCl (3 M) for 90 s (deposition step). After equilibrium time of 15 s, an ASV appeared at 0.0 V versus Ag|AgCl|KCl (3 M) (stripping step). The sensor depicted a fairly linear response for Cu²⁺ in the concentration range of 2–100 ppb with appropriate detection limit about 0.39 ppb and limit of quantification about 1.3 ppb. The stability of the modified electrode during 7 weeks and its behavior in the presence of some metal ions was evaluated. The practical applicability of the Sb₂O₃/CNTPE was established on the voltammetric determination of Cu²⁺ in tap water as a sample.     

Chelation ion-exchange properties of salicylic acid-urea-formaldehyde copolymers

Chelation ion-exchange properties of copolymers prepared from salicylic acid, urea and formaldehyde by condensation in presence of acid catalyst were studied for Cu²⁺, Fe³⁺, UO²⁺, Mn²⁺,Zn²⁺ and Co²⁺ ions. A batch equilibration method was adopted to study the selectivity of metal ion uptake. This method involved the measurement of distribution of a given metal between the copolymer sample and a solution containing the metal ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for UO₂ ²⁺, Cu²⁺ and Fe³⁺ ions than Mn²⁺, Co²⁺ and Zn²⁺ ions.     

Separation and Recovery of Some Metal Ions Using Pan Sorbed Zinc Silicate as Chelating Ion Exchanger

Abstract

A new inorganic ion exchanger zinc silicate has been synthesized. Its properties such as ion exchange capacity, heat effect and stability etc. have been studied. Sorption of PAN over zinc silicate formed a chelate ion exchanger which showed greater selectivity for some metal ions especially for Cu²⁺, Ni²⁺, Co²⁺, Fe³⁺, Ag⁺, Ag³⁺ and Pt⁴⁺. Selectivity has been determined on the basis of distribution coefficients of these metal ions. Separations of Pt(IV) from Fe(III), Au(III) from Fe(III), Ag(I) from Cu(II) and Au(III) from Cu(II) have been reported. The recovery of Pt(IV) and Au(III) from dilute solutions has also been studied.     

A novel ion selective membrane potentiometric sensor for direct determination of Fe(III) in the presence of Fe(II)

A new PVC membrane potentiometric sensor that is highly selective to Fe(III) ions was prepared by using 2-[(2-hydroxy-1-propenyl-buta-1,3-dienylimino)-methyl]-4-p-tolylazo-phenol [HPDTP] as a suitable carrier. The electrode exhibits a linear response for iron(III) ions over a wide concentration range (3.5 × 10⁻⁶ to 4.0 × 10⁻²) with a super Nernstian slope of 28.5 (±0.5) per decade. The electrode can be used in the pH range from 4.5 to 6.5. The proposed sensor shows fairly a good discriminating ability towards Fe³⁺ ion in comparison to some hard and soft metals such as Fe²⁺, Cd²⁺, Cu²⁺, Al³⁺ and Ca²⁺. It has a response time of <15 s and can be used for at least 2 months without any measurable divergence in response characteristics. The electrode was used in the direct determination of Fe³⁺ in aqueous samples and as an indicator electrode in potentiometric titration of Fe(III) ions.     

Synthesis and characterisation of a novel bi-nuclear copper2+ complex and its application as electrode-modifying agent for simultaneous voltammetric determination of dopamine and ascorbic acid

A new binuclear complex of copper²⁺, [LCu²⁺(CH₃COO)₂Cu²⁺L](CH₃COO)₂ where L is N,N-bis(phthalimide)ethylenediamine, was synthesised and characterised. The complex ion [LCu²⁺ (CH₃COO)₂Cu²⁺L]²⁺ was encapsulated into ZSM-5 zeolite and used to modify the surface of the glassy carbon electrode. This modified electrode, in a phosphate buffer solution at pH 7.0, exhibited an oxidation potential for dopamine (DA) and ascorbic acid (AA) at electrode potentials of 0.230 V and ?0.090 V vs. Ag/AgCl respectively, a separation of 0.320 V. The electro-oxidation of DA or AA on the modified electrode is independent of each other. No interference was observed from Na⁺, K⁺, Cl^?, SO ₄ ^2? , Mg²⁺, Ca²⁺, Zn²⁺, Fe²⁺, and glucose. The detection limits obtained were 2.91 × 10^?7 M for DA and 3.5 × 10^?7 M for AA.     

Multiplex sensor for detection of different metal ions based on on–off of fluorescent gold nanoclusters

In this study, a multiplex fluorescence sensor for successive detection of Fe³⁺, Cu²⁺ and Hg²⁺ ions based on “on–off” of fluorescence of a single type of gold nanoclusters (Au NCs) is described. Any of the Fe³⁺, Cu²⁺ and Hg²⁺ ions can cause quenching fluorescence of Au NCs, which established a sensitive sensor for detection of these ions respectively. With the introduction of ethylene diamine tetraacetic acid (EDTA) to the system of Au NCs and metal ions, a restoration of fluorescence may be found with the exception of Hg²⁺. A highly selective detection of Hg²⁺ ion is, thus, achieved by masking Fe³⁺ and Cu²⁺. On the other hand, the masking of Fe³⁺ and Cu²⁺ leads to the enhancement of fluorescence of Au NCs, which in turn provides an approach for successive determination of Fe³⁺ and Cu²⁺ based on “on–off” of fluorescence of Au NCs. Moreover, this assay was applied to the successful detection of Fe³⁺, Cu²⁺ and Hg²⁺ in fish, a good linear relationship was found between these metal ions and the degree of quenched fluorescent intensity. The dynamic ranges of Hg²⁺, Fe³⁺ and Cu²⁺ were 1.96 × 10⁻¹⁰–1.01 × 10⁻⁹, 1.28 × 10⁻⁷–1.27 × 10⁻⁶ and 1.2 × 10⁻⁷–1.2 × 10⁻⁶ M with high sensitivity (the limit of detection of Fe³⁺ 2.0 × 10⁻⁸ M, Cu²⁺ 1.9 × 10⁻⁸ M and Hg²⁺ 2 × 10⁻¹⁰ M). These results indicate that the assay is suitable for sensitive detection of these metal ions even under the coexistence, which can not only determine all three kinds of metal ions successively but also of detecting any or several kinds of metal ions.     

Highly Selective All‐Plastic,Disposable, Cu2+‐Selective Electrodes

Conducting polymers (CP) remain a promising material to construct stable potential all‐solid‐state ion‐selective potentiometric electrodes. The unique properties of poly(3,4‐ethylenedioxythiophene) doped with poly(4‐styrenesulfonate) ions, PEDOT‐PSS: high CP stability and affinity of doping anions towards Cu²⁺ ions, make it highly attractive for construction of all‐solid‐state copper(II)‐selective electrodes with outstanding selectivity. The additional benefits can arise from solution processability of commercially available PEDOT‐PSS system. This material was highly promising for a new sensor arrangement, i.e. to obtain disposable, planar and flexible all‐plastic Cu²⁺‐selective electrodes. These sensors can be obtained by casting a commercially available dispersion of PEDOT‐PSS (Baytron P) on a plastic, non‐conducting support material. The CP being both electrical lead and ion‐to‐electron transducer, was covered with plastic, solvent polymeric Cu²⁺ selective membrane. This extremely simple arrangement, after conditioning in dilute Cu²⁺ solution, was characterized with linear Nernstian responses within the activities range from: 0.1 to 10^?4 M, followed by super‐Nernstian responses for lower activities. The latter result points to effective elimination of primary ions leakage from the plastic membrane / transducer phase and has resulted in significantly improved selectivities. Obtained log K values were equal to ?7.6 for Co²⁺, ?7.4 for Zn²⁺, ?7.2 for Ca²⁺ and ?6.8 for Na⁺, respectively.     

Electron capture dissociation and collision-induced dissociation of metal ion (Ag+, Cu2+, Zn2+, Fe2+, and Fe3+) complexes of polyamidoamine (PAMAM) dendrimers

The electron capture dissociation (ECD) and collision-induced dissociation (CID) of complexes of polyamidoamine (PAMAM) dendrimers with metal ions Ag⁺, Cu²⁺, Zn²⁺, Fe²⁺, and Fe³⁺ were determined by Fourier transform ion cyclotron resonance mass spectrometry. Complexes were of the form [PD + M + mH]⁵⁺ where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2−4. Complementary information regarding the site and coordination chemistry of the metal ions can be obtained from the two techniques. The results suggest that complexes of Fe³⁺ and Cu²⁺ are coordinated via both core tertiary amines, whereas coordination of Ag⁺ involves a single core tertiary amine. The Zn²⁺ and Fe²⁺ complexes do not appear to involve coordination by the dendrimer core.     

Synthesis of new octakis(benzylthio)tetraazaporphyrin complexes with bivalent transition metal ions and an investigation of their spectral,redox and catalytic properties

Transition metals in the +2 oxidation state form complexes with octakis(benzylthio)tetraazaporphyrin [M{TAP(SBn)₈}] (M=Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and 2H⁺; Bn=CH₂Ph; TAP=tetraazaporphyrin) and were prepared via demetallation of the template-synthesized complex [Mg{TAP(SBn)₈}] in ClCH₂COOH, followed by insertion of the metal ions in a PhCl–DMF mixture. All compounds were characterized by u.v–vis, ¹H-n.m.r., e.s.r. and mass spectra, microanalyses and magnetic susceptibility data. PM3 geometry optimization showed near coplanar arrangement of five phenyl rings vis-à-vis the TAP ring plane, while the remaining three phenyl rings lie bent over it. The Mn²⁺, Co²⁺ and Cu²⁺ complexes exhibited reversible one electron oxidation waves, that were observed at E _1/2 -0.33, -0.29 and 0.58 V versus Ag/AgCl respectively. They all exhibited an irreversible reduction wave at E _p -1.1 V versusAg/AgCl followed by appearance of an irreversible oxidation wave at E _p 1.1–1.2 V versus Ag/AgCl. This has been interpreted in terms of reductive dissociation, leading to removal of the benzyl substituents, and subsequent oxidation of thiolate products. The Mn²⁺, Co²⁺ and Cu²⁺complexes exhibited metal ion-based e.s.r. signals. The [Co{TAP(SBn)₈}] complex in a homogeneous DMF solution was found to catalyze electro-reduction/oxidation of nitrite ions. In the presence of a 1/5 molar quantity of the complex [Co{TAP(SBn)₈}], the nitrite reduction peak was observed to be shifted by 0.1 V towards the positive potential side and the peak current rose by a factor of 1.33. Similarly a sharp rise in the anodic current, corresponding to oxidation of nitrite ions, was observed in the presence of the complex.     

A novel BF<Subscript>2</Subscript>–curcumin-based fluorescent chemosensor for detection of Cu<Superscript>2+</Superscript> in aqueous solution and living cells

A novel BF₂–curcumin-based chemosensor 1, namely monopicolinate of BF₂–curcumin complex, was designed, synthesized and applied for the detection of Cu²⁺ in aqueous buffer solution and living cells. Sensor 1 exhibited sensitive naked-eye color change toward Cu²⁺ from blue to pink in TBS solution and the detection limit was estimated to be 0.12 µM. The selectivity of sensor 1 for Cu²⁺ was high over competing metal ions (Ag⁺, Cu⁺, Hg²⁺, Mg²⁺, Ca²⁺, Co²⁺, Zn²⁺, Mn²⁺, Ni²⁺, Fe²⁺ and Fe³⁺). Based on the experimental results, the sensing mechanism was proposed for the Cu²⁺ triggered hydrolysis of 1 to BF₂–curcumin which has unique chromogenic and fluorogenic properties. Compared with other chemosensors with a similar mechanism, chemosensor 1 had a comparatively large Stokes shift and the emission wavelength was close to NIR. Moreover, cell imaging investigations indicated that sensor 1 has the potential to be applied for practical Cu²⁺ detection in biological systems.     

A highly selective fluorescent chemosensor for Fe (III) based on rhodamine 6G dyes derivative

A new fluorescent probe L based on the rhodamine 6G platforms for Fe³⁺ has been designed and synthesised. L showed excellent selectivity and high sensitivity for Fe³⁺ against other metal ions such as K⁺, Na⁺, Ag⁺, Cu²⁺, Co²⁺, Mg²⁺, Cd²⁺, Ni²⁺, Zn²⁺, Fe²⁺, Hg²⁺, Ce³⁺ and Y³⁺ in HEPES buffer (10 mM, pH 7.4)/CH₃CN (40:60, V/V). The distinct color change and the rapid emergence of fluorescence emission provided naked-eyes detection for Fe³⁺. The recognition mechanism of the probe toward Fe³⁺ was evaluated by Job’s plots, IR and ESI-MS. In order to further study their fluorescent properties, L + Fe³⁺ fluorescence lifetime was also measured. Moreover, the test strip results showed that these probes could act as a convenient and efficient Fe³⁺ test kit.     

Copper (II) Sensor Based on a Cephaloridine Antibiotic PVC Matrix

ABSTRACT

A poly (vinyl chloride) (PVC) based membrane of cephaloridine as a novel ionophore exhibits good potentiometric response for Cu²⁺ over a wide concentration range (10^?5-10^? M) with a slope of 28.5 mV per decade. The detection limit is 3.5 × 10^?6 M. The response time of the sensor is < 60 s. The electrode has been used for a period of one month and exhibits good selectivity towards Cu²⁺ in comparison to alkali, alkaline earth, transition and heavy metal ions, with no interference caused by Pb²⁺ Cd²⁺ and Fe²⁺ which are known to interfere with many other copper electrodes. The electrode can be used in the pH range from 4.0 to 6.5 and it can also be used in partially non-aqueous medium having up to 10 (v/v) non aqueous content and in the presence of cationic surfactants at concentrations less than 10^?3 M.