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.     

Terbium(III) Ion-Selective Electrochemical Sensor Based on Hematoporphyrin

Abstract

A polyvinyl chloride (PVC) based membrane sensor for terbium ions was prepared by employing Hematoporphyrin (HP) as an ionophore. The sensor revealed a very good selectivity (expect for the Fe³⁺ion) with respect to common alkali, alkaline earth and heavy metal ions. The plasticized membrane electrode exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 ? 1.0 × 10^?2 M) with a slope of 19.8±0.3 mV per decade and low detection limit of 7.4 × 10^?7 M. The developed sensor was used in determination of F^? in mouth wash preparation sample.     

Tb3+ PVC-Membrane Electrode Based on 2-{2-(2-Anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazine Carbothioamide

Abstract

The polyvinyl chloride (PVC) membrane containing 2-{2-(2-anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazinecarbothioamide (AHC) as a suitable iophore exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 to 1.0 × 10^?2 M) with a slope of 19.6 ± 0.3 mV per decade and a limit of detection of 6.8 × 10^?7 M in the pH range 3.5–8.5. The proposed sensor revealed very good selectivities (expect for the Pr³⁺ and Ho³⁺ ions) for a wide variety of other metal ions. The practical utility of the electrodes has been demonstrated by its use for the determination of Tb³⁺ in different solutions.     

Lanthanide Recognition: Development of an Asymetric Gadolinium Microsensor Based on N-(2-pyridyl)-N′-(4-nitrophenyl)thiourea

Abstract

The first asymmetric potentiometric Gd(III) microsensor is reported here. N-(2-Pyridyl)-N′-(4-nitrophenyl)thiourea (PyTu₄NO₂) was found to have a very selective and sensitive behavior toward Gd(III) ions, in comparison to other lanthanide ions as well as inner transition and representative metal ions and hence was used as a sensing material in the construction of a Gd(III) microelectrode. The Gd(III) sensor exhibits a Nernstian slope of 17.46 ± 0.3 mV per decade over the concentration range of 1.0 × 10^?8 to 1.0 × 10^?3 M and a detection limit of 3.0 × 10^?9 M of Gd(III) ions. The potentiometric response of the sensor is independent of the solution pH in the range of 4.0–9.0. It manifests advantages of low detection limit and fast response time (10–15 s).     

2-(2′-Hydroxyphenyl)-4(3H)-quinazolinone derivatives based fluorescent probes for mercury(II) via an intramolecular proton transfer mechanism

2-(2′,5′-Dihydroxy-phenyl)-4(3H)-quinazolinone (DHPQ), a new fluorescent dye that exhibits excited state intramolecular proton transfer (ESIPT) reaction and possesses good photophysical properties, is synthesised and used as fluorescent probe for detection of Hg²⁺. Mercuric ions can be detected and quantitated by measuring the fluorescent intensity decrease of the probe. The decrease of fluorescence intensity of DHPQ upon the addition of Hg²⁺ was attributed to the blocking of ESIPT reactions of DHPQ and quenching its fluorescence. The analytical performance characteristics of the proposed Hg²⁺ probe were investigated. The probe can be applied to the quantification of Hg²⁺ with a concentration range covering from 8.0?×?10^?7 to 2.0?×?10^?4?mol?L^?1, with a working pH range of 5.5–6.5. It shows excellent selectivity for Hg²⁺ over other transition metal cations. The proposed method was testified for the Hg²⁺ assay in river water samples with satisfying recoveries.     

Magnesium-PVC Membrane Sensor Based on 4,5-Bis(Benzoylthio)-1,3-Dithiole-2-Thione

Abstract

This report describes an attempt to develop potentiometric Mg²⁺ sensors based on a liquid polymeric membrane. Membrane incorporating 4,5-Bis(benzoylthio)-1,3- dithiole-2-thione (Bz₂dmit) as ionophore, with composition Bz₂ dmit:NaTPB:NB:PVC in the ratio 2.5:2.5:65:30 (w/w), exhibits the best result for potentiometric sensing of Mg²⁺ ions. The proposed electrode, based on Bz₂ dmitwith nitrobenzene (NB) as a solvent mediator in a polyvinyl chloride (PVC) membrane matrix, exhibited a near-Nernstian response to Mg²⁺ in the concentration range of 1.0 × 10^?5 to 1.0 × 10^?1 M, with a slope of 29.2 mV per decade of activity of Mg²⁺. The lower limit of detection was 1.0 × 10^?5 M. This sensor showed high selectivity with respect to alkaline, alkaline earth, transition, and heavy metal ions, except for Sr²⁺, and could be used over a pH range of 3.5–9.0. It can be used for at least 2 mo without considerable divergence in potentials and has a relatively fast response of <10 s. It was applied successfully as an indicator electrode in potentiometric titration of Mg²⁺ ions with EDTA.     

Development of Fluorescent Film Sensors Based on Electropolymerization for Iron(III) Ion Detection

Two electroactive materials, M1 and M2 , are synthesized and their fluorescent electropolymerized (EP) films are prepared and used to detect metal ions. From the tested metal ions, M1 and M2 are demonstrated to be sensitive and selective for Fe³⁺ ions. In particular, M2 exhibits higher sensitivity towards Fe³⁺ ions. The fluorescent detection ranges from 10^?5 M to 4×10^?4 M . The excellent performance of the EP fluorescent films is mainly due to the strong metal‐chelated properties of M2 and the intrinsic porous cross‐linked‐network microstructure of the EP films. This study, thus, provides a promising Fe³⁺ sensing candidate and a potential preparation method for fluorescent sensing films.     

Lanthanide Recognition: Determination of Thulium(III) Ions in Presence of Other Rare Earth Elements by a Thulium(III) Sensor Based on 4-Methyl-1,2-Bis(2-Pyridinecarboxamido)benzene as a Sensing Material

Abstract

In this research, a novel thulium(III) potentiometric membrane sensor based on 4-methyl-1,2-bis(2-pyridinecarboxamido) benzene (MPB) is described. The sensor exhibits a Nernstian response over a concentration range of 1.0 × 10^?7 M to 1.0 × 10^?1 M, with a detection limit of 9.0 × 10^?8 M. The best performance was achieved with a membrane composition of 30% PVC, 60% nitrobenzene (NB), 6% MPB, and 4% sodium tetraphenylborate (NaTPB). It was found that at the pH range of 3.6 to 9.0, the potential response of the sensor was not affected by the pH. Furthermore, the electrode presents satisfactory reproducibility, very fast response time (15 s), and relatively good discriminating ability for Tm(III) ions with respect to many common cations and lanthanide ions. The validation of the proposed electrode was tested by using Coal and Fuel Ash (FFA 1 Fly Ash) as a Certified Reference Material (CRM).     

Preparation of Cu (II) imprinted polymer electrode and its application for potentiometric and voltammetric determination of Cu (II)

The Cu (II) imprinted polymer glassy carbon electrode (GCE/Cu-IP) was prepared by electropolymerization of pyrrole at GCE in the presence of methyl red as a dopant and then imprinting by Cu²⁺ ions. This electrode was applied for potentiometric and voltammetric detection of Cu²⁺ ion. The potentiometric response of the electrode was linear within the Cu²⁺ concentration range of 3.9 × 10^?6 to 5.0 × 10^?2 M with a near-Nernstian slope of 29.0 mV decade^?1 and a detection limit of 5.0 × 10^?7 M. The electrode was also used for preconcentration anodic stripping voltammetry and results exhibited that peak currents for the incorporated copper species were dependent on the metal ion concentration in the range of 1.0 × 10^?8 to 1.0 × 10^?3 M and detection limit was 6.5 × 10^?9 M. Also the selectivity of the prepared electrode was investigated. The imprinted polymer electrode was used for the successful assay of copper in two standard reference material samples.     

A Novel Fluorescence Sensor for Cocaine with Signal Amplification through Cycling Exo-Cleaving with a Hairpin Probe

A novel fluorescence assay, based on the signal amplification through cycling reactions of aptameric recognition and nucleic acid exo-cleaving, was established for the sensitive detection of cocaine. In this assay, a new single fluorophore-labeled DNA-hairpin probe was used. This smart probe was established based on the significant nucleobase quenching between the nucleobases and the fluorophore. In the presence of cocaine and its aptamer, the structure of the smart probe changed to recover the fluorescence. In order to enhance the sensitivity of this assay, exonuclease III was introduced to enable the inputted cocaine to react with multiple probes in a recycling manner. Under the optimal conditions, a linear range for cocaine from 4.0 × 10^?9 to 8.0 × 10^?8 M with a detection limit of 1.76 × 10^?9 M (3σ, n = 11) was obtained.     

Used a new aza-thia-macrocycle as a suitable carrier in potentiometric sensor of copper (II)

A new modified carbon paste electrode for determination of Cu²⁺ made in our laboratory that used a new synthesized macrocycle 7,16-diaza-1-thia-4,10,13,19-tetraoxa-6,17-dioxo-2,3;20,21-dinaphtho-cyclouneicosane as modifier. This sensor exhibits a good affinity toward copper (II) ions over a wide variety of other metal ions. The electrode exhibits a Nernstian slope of 30 (±0.5) mV per decade for copper (II) ions over a wide concentration range (1.0 × 10^?8–1.0 × 10^?2 mol L^?1), with a limit of detection of 7.0 × 10^?9 mol L^?1 (~0.45 ppb). It has a response time of 30 s and can be used for at least 3 months without any considerable divergence in responses. The potentiometric response of the electrode is independent of the pH of test solution in the pH range 3.5–7.5. Finally, it was successfully used as an indicator electrode for determination of copper (II) in real samples such as Karoun river and tap water.     

Highly selective fluorescent probe based on a rhodamine B and furan-2-carbonyl chloride conjugate for detection of Fe3+ in cells

A furan-2-carbonyl chloride modified rhodamine B derivative (RBFC) has been designed and synthesized. The probe RBFC exhibited excellent sensitivity and selectivity for detection of Fe³⁺ with a 1:1 stoichiometry over other tested metal ions in a MeOH/H₂O (1:1, v/v, pH 7.36, HEPES buffer, 1.3?mM) solution. The association constant and the detection limit were calculated to be 7.28?×?10³?M^?1 and 0.437?μM based on fluorescence titration analysis. Furthermore, the probe RBFC was successfully applied in living cells, and the results indicated that the probe could monitor intracellular Fe³⁺ in MCF-7 cells.     

Mercury selective membrane electrode based on dithio derivatized macrotricyclic compound

A novel dithio derivatized macrotricyclic compound (cryptand) has been synthesized using high dilution technique by condensation of diaminodibenzo18-crown-6 with 2, 2′dithiobenzoyl chloride. The compound was characterized by elemental analysis, ¹H NMR, ¹³C NMR and FAB-MS. PVC membrane electrode based on this macrotricyclic compound showed good selectivity for Hg²⁺ ion with a wide linear range of 1.0 × 10^?6 to 1.0 × 10^?1 M and a lower detection limit of 5.0 × 10^?6 M with a calibration slope of 30.2 mV decade^?1. The electrode response was stable in pH range 3–6. Electrode showed good selectivity for Hg²⁺ over other interfering metal ions. The electrode was then applied to direct determination of Hg²⁺ in water samples.     

Highly Selective and Sensitive Tin(II) Membrane Electrode Based on a New Synthesized Schiff's Base

Studies on complex formation of tris(3‐(2‐hydroxybenzophenone)propyl)amine (THPA) with a number of metal ions in acetonitrile solution revealed the occurrence of a selective 1 : 1 complexation of the proposed ligand with Sn²⁺ ion. Consequently, THPA was used as a suitable neutral ionophore for the preparation of a polymeric membrane‐selective electrode. The electrode exhibits a Nernstian behavior with a slope of 29.4±0.3 mV per decade and a detection limit of 2.0×10^?7 M. It also showed a good selectivity for Sn²⁺ ions in comparison with some of group A and B metal ions over a wide concentration range of 5.0×10^?7–1.0×10^?1 M. Improved selectivity was achieved compared to the best selectivity recently reported by other authors for tin(II). The electrode was successfully applied to the determination of Sn²⁺ ion in waste water and various canned products.     

Quinoline-based highly selective and sensitive fluorescent probe specific for Cd2+ detection in mixed aqueous media

Quinoline-based fluorescent probe as a recognition unit was designed and synthesized in this study. The probe R1 displayed excellent selectivity and sensitivity for cadmium ions (Cd²⁺) over a wide range of metal ions in acetonitrile-water (MeCN-H₂O) mixed solution. In order to better understand the recognition mechanism between probe and Cd²⁺, the density functional theory calculations were performed. Finally, the colorimetric experiment result was observed and conveniently monitored by the naked eye, and a visual detection limit of 4 × 10^?6 mol L^?1 was achieved. These experimental results indicated the promising potential of the probe to detect Cd²⁺ in biological system. Furthermore, the probe R1 was successfully used for the highly sensitive detection of Cd²⁺ in living cells.     

A lead (II) selective PVC membrane potentiometric sensor based on a tetraazamacrocyclic ligand

A polymeric membrane based Pb(II) selective potentiometric sensor was developed by using 1,3,7,9-tetraaza-2,8-dithia-4,10-dimethyl-6,12-diphenylcyclododeca-4,6,10,12-tetraene (TDDDCT) as an electroactive material along with anion excluder sodium tetraphenylborate (NaTPB) and plasticizer dioctylphthalate (DOP). The best performance in terms of slope, concentration range and response time was exhibited by the membrane having TDDDCT:PVC:DOP:NaTPB in the ratio 3:32:62:3 (w/w%). Potentiometric results show that the developed sensor works well in the concentration range 5.0 × 10^?7–1.0 × 10^?1 M with a near Nernstian slope of 29.5 (±0.5) mV decade^?1. The detection limit is down to 2.5 × 10^?7 M. The working pH range of this sensor is 2.8–7.0 and it works well in partially nonaqueous medium up to 25 % (v/v) methanol and ethanol. It exhibits a fast response time of 10 s. Selectivity coefficient values of various interfering ions were determined by the fixed interference method (FIM). The sensor reveals good selectivity for Pb(II) ions over other metal ions investigated. The developed sensor is used in the determination of lead in ‘Eveready battery waste’ and as an indicator electrode in the potentiometric titration of Pb(II) against EDTA.     

A Novel Holmium(III) Membrane Sensor Based on N‐(1‐Thien‐2‐Ylmethylene)‐1,3‐Benzothiazol‐2‐Amine

Abstract

A novel plasticized membrane sensor for Ho(III) ions based on N‐(1‐thien‐2‐ylmethylene)‐1,3‐benzothiazol‐2‐amine (TBA) as a neutral carrier was prepared. The best performance was obtained with a membrane composition of 31% PVC, 61% benzyle acetate, 2% sodium tetra phenyl borate and 6% carrier. The electrode exhibits a Nernstian response for Ho(III) ions over a particular concentration range (1.0×10^?5?1.0×10^?2 M) with a slope of 19.7±0.2 mV decade^?1. The limit of the detection is 7.0×10^?6 M. The sensor has a response time of <15 s and a useful working pH range of 4.0–9.5. The proposed sensor discriminates relatively well towards Ho(III) ions with regard to common alkali, alkaline earth, and specially lanthanide ions. It was successfully applied as an indicator electrode in a potentiometric titration of Ho(III) ions with EDTA. It was also applied in determination of fluoride ions in a mouth wash preparation. The proposed sensor was applied for the determination of Ho(III) ion concentration in binary mixtures.     

Determination of Hg(II) ions in water samples by a novel Hg(II) sensor,based on calix[4]arene derivative

A PVC membrane electrode for Hg(II) ions, based on a new cone shaped calix[4]arene (L) as a suitable ionophore was constructed. The sensor exhibits a linear dynamic in the range of 1.0 × 10^?6–1.0 × 10^?1 M, with a Nernstian slope of 29.4 ± 0.4 mV decade^?1, and a detection limit of 4.0 × 10^?7 M. The response time is quick (less than 10 s), it can be used in the pH range of 1.5–4, and the electrode response and selectivity remained almost unchanged for about 2 months. The sensor revealed comparatively good selectivity with respect to most alkali, alkaline earth, and some transition and heavy metal ions. It was successfully employed as an indicator electrode in the potentiometric titration of Hg²⁺ ions with potassium iodide, and the direct determination of mercury content of amalgam alloy and water samples.     

1,3,4-Trisubstituted-2-azetidinone Derivatives as Novel Receptors for Bismuth(III) Ion-Selective Electrodes: Application in Pharmaceutical and Glass Samples

Abstract

Polymeric membrane electrodes (PMEs) and coated graphite electrodes (CGEs) containing 1,3,4-trisubstituted-2-azetidinone derivatives as ion carriers are reported here for bismuth(III) ion selectivity. These electrodes exhibited Nernstian response for Bi³⁺ ions over a wide concentration range (5.0 × 10^?7 M to 1.0 × 10^?1 M for CGE) with a lower detection limit of 3.98 × 10^?7 M (for CGE) and wide pH range (1.3–5.0). Compared to polymeric membrane electrode, the coated graphite electrode has shown better selectivity for Bi³⁺ ions with respect to common metal ions. Proposed electrodes have been used for the estimation of Bi³⁺ ions in pharmaceutical and glass samples.     

A Novel PVC‐Membrane‐Coated Graphite Sensor Based on an Anthraquinone Derivative Membrane for the Determination of Lead

A highly selective membrane electrode for the determination of ultratrace amounts of lead was prepared. The PVC membrane electrode based on 2‐(2‐ethanoloxymethyl)‐1‐hydroxy‐9,10‐anthraquinone (AQ), directly coated on graphite, exhibits a good Nernstian response for Pb(II) ions over a very wide concentration range (1.0×10^?7–1.0×10^?2 M) with a limit of detection of 8.0×10^?8 M. It has a fast response time of ca. 10 s and can be used over a period 2 months with good reproducibility (SD=±0.2 mV). The electrode revealed a very good selectivity respect to common alkali, alkaline earth, transition and heavy metal ions and could be used in the pH range of 3.5–6.8. It was used as an indicator electrode in potentiometric titration of lead ions with chromate and oxalate, and in indirect determination of lead in spring water samples.