Ions In Aqueous Media Research Articles

Pyridine-2,6-Dicarboxylic Acid As a Facile and Highly Selective "Turn-Off" Fluorimetric Chemosensor for Detection of Cu (II) Ions in Aqueous Media.

Copper metal is third most abundant trace element in human body. Determination of Cu (II) ions is a burning topic in field of environment protection and food safety because of its significant impact on ecosystem. In this study, 2,6-pyridine dicarboxylic acid (PDA) has been explored as "turn-off" florescent probe for florescent detection of Cu (II) ions. This sensor showed highly selective complexing ability towards Cu (II) ions. Addition of aqueous solution of Cu (II) ions remarkably quenched the fluorescence intensity of PDA while, on contrary, there was no any prominent fluorescence quenching interference on addition of various metal ions. The binding mode of PDA and Cu (II) ions was determined as stoichiometry of 1:1 and it was further confirmed by single crystal XRD analysis. Mechanisms of static and dynamic quenching were confirmed by stern-volmer plot. Limit of detection (LOD) and limit of quantification (LOQ) for Cu (II) ions was calculated as 3.6 µM and 1.23 µM respectively, which is far below the acceptable value (31.5µM) according to the World Health Organization. The use of the sensor for detection of Cu (II) ions in real samples in aqueous media was also performed.

Green synthesized AgNPs as a probe for colorimetric detection of Hg (II) ions in aqueous medium and fluorescent imaging in liver cell lines and its antibacterial activity

The present research aimed at green synthesis of Ag nanoparticles (AgNPs) based colorimetric sensor using persimmon leaf extract (PLE) for selective detection of mercuric ion (Hg2+). Optimization of reaction conditions viz. pH, concentration of PLE, time was done and further AgNPs were characterized using UV, IR, FE-SEM, EDX, XRD and TEM analysis. The developed AgNPs were evaluated for the selective colorimetric detection of Hg2+ in aqueous medium and fluorescence imaging of Hg2+ ions in liver cell lines. Later, the antibacterial activity of AgNPs was performed against S. aureus and E. coli. The findings of the study revealed that PLE mediated AgNPs exhibited notable limit of detection up to 0.1 ppb, high efficiency, and stability. The antibacterial study indicated that developed AgNPs has impressive bacterial inhibiting properties against the tested bacterial strains. In conclusion, developed biogenic AgNPs has high selectivity and notable sensitivity towards Hg2+ ions and may be used as key tool water remediation.Graphical abstract

A highly selective multifunctional naphthalene-labeled polymer sensor for Cu2+ and Fe3+ ions in aqueous medium

In this work, the detection of Cu2+ and Fe3+ with naphthalene labeled poly(acrylic acid) (PAA150Np3) was investigated. Other metal ions such as Ag+, Li+, K+, Na+, Ba2+, Mg2+, Ca2+, Zn2+ and Ni2+ were also considered to analyze the sensor performance. The fluorescence quenching of the naphthalene (Np) graft was assessed from the emission spectra and the fluorescence decays of PAA150Np3 in the presence of Cu2+ or Fe3+. The Stern-Volmer and Hill constants, as well as the detection limits of the studied ions were obtained considering the emissions of both the monomer and the excimer of Np. The polymer conformation was investigated by changing the metal ion concentration or the pH. The polymeric sensor showed high selectivity and sensitivity for Cu2+ or Fe3+. A static mechanism of fluorescence quenching was unveiled for the Np graft. A more stable complex formed between PAA150Np3 and Fe3+, as compared to the counterpart system with Cu2+. The sensor’s performance, including detection limit and selectivity of Cu2+ or Fe3+ ions, is higher than of most currently reported sensors. The study shows that the multifunctional fluorescent polymer sensor has the potential to be used in real-life samples, in bio-systems and environmental applications.

Synthesis and characterization of a unique fused spiro-dihydropyran based chemodosimeter for selective visual and fluorescent detection of Cu2+ ion in aqueous medium by “turn-on” mode

A realistically newly designed Cu2+ ion specific fluorescent chemodosimeter has been synthesized from α,α'-(E,E)-bis(benzylidene)cyclohexanone having a fused spiro-dihydropyran moiety characterized by 2D NMR and X-Ray Crystallographic study. It also demonstrates an irreversible, instant direct visualisation by unaided eye chemosensing property in aqueous buffer (pH 7.4) with a colour change from yellow to orange upto 0.3 × 10−6 M.

Enhancing antimicrobial efficacy: 8-Hydroxyquinoline incorporation into metal-organic frameworks with iron ion coupling

The antimicrobial properties of 8-Hydroxyquinoline (8-Hq), a small organic compound known for its metal-chelating capabilities, hold significant promise. However, its limited solubility in water poses a challenge for practical applications. In this study, we address this limitation by augmenting the antimicrobial efficacy of 8-Hq through its integration into the metal-organic framework UiO-66 (named 8-Hq@UiO-66) and coupling it with iron ions (designated as Fe/8-Hq@UiO-66) via an adsorption process. The sorption isotherm and adsorption kinetics were meticulously examined using Langmuir's adsorption model and the pseudo-second-order kinetic model. Material characterization techniques including powder X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption isotherms, ultraviolet–visible spectroscopy, and photoluminescence spectroscopy revealed the coordination of zirconium clusters and iron with the nitrogen and hydroxyl groups of 8-Hq, respectively. Furthermore, our investigation into metal ion adsorption demonstrated that the 8-Hq@UiO-66 composite displayed a notable selectivity for iron ions over other metal ions in aqueous media. Under optimized conditions, the adsorption capacity for iron ions ranged from approximately 34–46 mg g−1. Importantly, the Fe/8-Hq@UiO-66 composite exhibited potent antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. These findings underscore the potential of incorporating 8-Hq into porous metal-organic frameworks and coupling it with iron ions to enhance its antimicrobial efficacy.

Rapid preconcentration and determination of Co (II) ions in aqueous medium using ultrasound assisted cloud point extraction method

A flame atomic absorption spectrophotometric technique was studied for the preconcentration and determination of of Co2+ ions in trace amounts after ultrasound enhanced enrichment of its 1-(2-pyridylazo)-2-naphthol (PAN) complexes by cloud point extraction. The Co2+ ions were firstly complexed with PAN molecules at pH 4 and the complex transferred to a surfactant (Tergitol NP-7) rich phase with a very small volume under ultrasound waves. The surfactant rich phase was separated and dissolved by 1 mL, 1.0 M HNO3 in ethanol prior to determination of Co2+ concentration by flame atomic absorption spectrophotometry. The optimization steps of ultrasound interaction time, solution pH and surfactant volumes were achieved by response surface methodology (RSM) which is a combination of statistical approaches. Sample volume, PAN concentration and and possible interfering ions were optimized conventionally. The Co2+ ions were extracted only in 150 s at pH 4 quantitatively under optimum conditions (˃95%). The accuracy and validity of developed UA-CPE was granted by employing a certified reference material wastewater UME CRM 1204. The technique was applied to wastewater and natural water with satisfactory results.

New 2-{[(2-chloroquinolin-3-yl)Methylidene]amino}phenol (CQMAP) Schiff-base as colorimetric Chemosensor for Cr(III) detection: An Experimental and DFT Exploration

In this investigation, a new Cr(III)-chemosensor, 2-{[(2-chloroquinolin-3-yl)methylidene]amino}phenol (CQMAP), had been successfully synthesized and characterized. The new chemosensor had been characterized using both NMR and FT-IR spectroscopy techniques. The CQMAP showcased remarkable sensitivity & selectivity, specifically against Cr(III) ions in aqueous media, even when challenged with various competing cations, such as Na(I), Mg(II), Al(III), K(I), Ca(II), Mn(II), Fe(II), Co(II), Ni(II), Zn(II), Sr(II), Ag(I), Cd(II), and Pb(II) respectively. The improved chemosensor underwent a distinctive colour transition to pale blue, offering a simple, clear and straightforward indication of Cr(III) presence. The CQMAP demonstrated a colorimetric assay for the optical/visual detection of Cr(III) ions with a detection limit of 14.65 ± 1.02 µM. The sensing action had been proposed by the formation of a complex with Cr(III) in a 1:3 stoichiometry (Cr(III) : CQMAP). Furthermore, the synthesized CQMAP underwent a meticulous characterization process using FT-IR, mass, Uv-vis. Spectroscopy, Thermal, conductivity, and magnetic behaviour measurements. The CrCQMAP complex had a binding constant of 1.84±1.21×104 M−1, forming a 1:3 stoichiometry with Cr(III) ions, providing insights into the strength of the interaction. These findings collectively underscore the robustness and versatility of CQMAP as an effective chemosensor for Cr(III) detection, showcasing its potential across diverse applications, including environmental monitoring and analytical chemistry.

TPE[2]arenes: Luminescent macrocyclic arenes with aggregation-induced emission and Al3+ detection

Luminescent macrocyclic arenes have attracted interest owing to their unique cyclic geometry and adaptive emission. Herein, a series of fluorescent macrocyclic arenes, denoted as TPE [2]arenes, were easily synthesized by the one-pot condensation of tetraphenylethene (TPE) moiety and paraformaldehyde in the presence of BF3·OEt2 and readily derivatized to yield cyclic arenes with diverse substitution patterns. The macrocyclic arenes shared similar cyclic skeleton with resorcin [4]arene, and existed as two enantiomers with boat conformation confirmed via single crystal analysis. Furthermore, TPE [2]arenes all retained the aggregation-induced emission properties owing to the incorporation of TPE moiety and obvious mechanochromic luminescence behavior due to the relative flexible skeleton. The carboxylic acid substituted analogues, namely TPE [2]arene-COOH, exhibited specific “turn-on” detection of Al3+ ion in aqueous media.

Solvothermal self-assembly of seven lanthanide(III) coordination polymers using diphenic acid and 1,10-phenanthroline as co-ligands: Efficient detection of picric acid and Cu2+ ions in aqueous medium by europium based coordination polymer

Lanthanide based coordination polymers (Ln-CPs) act as efficient chemo-sensors on interaction with the target analyte and show a detectable variation in their optical properties. This work demonstrates interaction of metal ions and nitroaromatic compounds with Eu based CP resulting in quenching of luminescence emission intensity. Approaching towards this aim, seven iso-structural lanthanide coordination polymers having the formulae, [Ln(diphen)1.5(1,10-phen)(H2O)] where Ln = Sm (1), Gd (3), Dy (5), {[Ln(diphen)1.5(1,10-phen)(H2O)]·OH} Ln = Eu (2), Er (7) and {[Ln(diphen)1.5(1,10-phen)(H2O)]·CH3CN·H2O} Ln = Gd (4), Ho (6) (diphen = diphenic acid, 1,10-phen = 1,10 Phenanthroline), were assembled solvothermally by using diphenic acid and 1,10-Phenanthroline as ligands. These lanthanide coordination polymers were characterized by Single-crystal X-ray diffraction, FTIR, Powder X-ray diffraction, Thermogravimetric analysis, UV–visible spectroscopy and Photoluminescence. The CPs 1–7 possess one-dimensional (1D) infinite chain-like structures which crystallize in the monoclinic C2/c space group. The photoluminescence properties of CP 2 exhibit its sensing ability to detect some toxic nitroaromatic compounds and d-block metal ions. However, CP 2 shows highly sensitive behavior for the recognition of Cu2+ and picric acid as indicated by efficient luminescence quenching with the low limit of detection. Other metal ions (viz., Cr3+, Cu2+, Co2+, Zn2+, Mn2+, Ni2+, Cd2+, and Hg2+), and nitro compounds (viz., PA, m-DNB, p-NP, p-NA and NB) were also screened for sensing potential of CP 2.

Preparation of novel CS/SiO2-EDTA nanocomposite from ash of rice straw pellets for enhanced removal efficiency of heavy metal ions in aqueous medium

The production valuable materials from waste for environmental treatment have attracted considerable attention worldwide. In this study, porous silica was produced from the ash of rice straw pellets. The porous silica was then modified with chitosan (CS) and ethylenediaminetetraacetic acid (EDTA) to produce novel CS/SiO2-EDTA nanocomposites for the removal of heavy metals in aqueous medium. The adsorption of Pb2+ was investigated to evaluate the effectiveness of the composite and the effects of reaction parameters on the adsorption process were extensively explored. The adsorption is fast in the initial 5 min, then almost reaches equilibrium in 10 min. The conditions for the highest adsorption capacity are an EDTA content of 1.0 M, a pH of 6, an adsorbent dosage of 0.1 g/L, and a Pb2+ concentration of 100 ppm. The removal efficiency, adsorption capacity, and rate constant are 70.39 %, 703.9 ± 21.1 mg/g, and 0.012 ± 0.003 g/mg·min, respectively. The conditions for the highest adsorption efficiency are an EDTA content of 1.0 M, a pH of 6, an adsorbent dosage of 0.5 g/L, and a Pb2+ concentration of 40 ppm, where the adsorption efficiency, adsorption capacity, and rate constant are 89.88 %, 71.91 ± 1.86 mg/g, and 0.013 ± 0.002 g/mg·min, respectively. The selectivity of the composite was investigated by using Ni2+, Cu2+ and Fe2+ ions under the same experimental conditions. In multi-metal solutions, the adsorbent showed the highest affinity for Pb2+. In addition, the adsorption isotherms and thermodynamics were investigated and an adsorption mechanism was proposed.

Recyclable magnetic nickel ferrite–carboxymethyl cellulose–sodium alginate bio-composite for efficient removal of nickel ion from water

In waste water treatment, magnetic bio-composites are frequently investigated as an adsorbent recently due to their great capacity for adsorption and affordability. In this current work, an attempt has been made to develop spinel nickel ferrite–carboxymethyl cellulose (NiFCMC) composite and modified its surface by alginate polymer to form NiFCMC–Alg composite. Several techniques were utilized to characterize these adsorbents including Fourier transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectra, thermogravimetric analysis, vibration sample magnetometry and pH of point zero charge. These adsorbents were explored to check their potentiality to remove Ni (II) ions in aqueous medium on various parameters such as contact time, initial metal ion concentration, pH, adsorbent dose and temperature. The optimum time for establishment of equilibrium was 180 minutes at pH 8 with adsorbent dose of 0.1 g. Results of kinetic studies revealed that the best fit for the metal ion adsorption data was the Lagergren pseudo-second-order mode indicating the chemisorption nature. Likewise, the Langmuir isotherm model also showed good agreement with adsorption equilibrium data with maximum adsorption capacities 47.84 ± 2.39 and 60.24 ± 3.01 mg/g for NiFCMC and NiFCMC–Alg respectively. The calculated adsorption thermodynamic parameters confirmed the spontaneous nature of adsorption process. The regeneration efficiency of both adsorbents was studied for five cycles and showed significant results. This study has shown that NiFCMC and NiFCMC–Alg can be a good substitute for removing Ni (II) ions in aqueous medium.

A zwitterionic probe for ratiometric fluorescent detection of aluminium(III) ion in aqueous medium and its application in bioimaging

In the present study, we have synthesized an aminobenzoic acid containing Schiff base (compound 1) and its structure was confirmed through single crystal X-ray study. Importantly, the compound 1 crystallizes in the zwitterionic form, with an anionic carboxylate group (–COO−) and a cationic iminium group (–C = NH+–). The compound 1 is highly soluble in water due to its zwitterionic feature in the solid state. Interestingly, compound 1 acts as a ratiometric fluorescent probe for the selective detection of Al3+ ion in aqueous solution without organic cosolvent. It can also detect Al3+ ion by visual colour change to bluish-green fluorescence under 365 nm UV light. The association constant between compound 1 with Al3+ ion was estimated to be 1.67 × 104 M−1. The lowest detection limit for Al3+ ion was calculated to be 7.05 × 10−8 M in water. Compound 1 in combination with Al3+ ion demonstrated fluorescent imaging potential of the nucleus of in RAW 264.7 murine macrophage cell line. In addition, the sensing model is developed as paper based sensor ''Test Kit' 'for its practical applicability.

Water-stable boroxine structure with dynamic covalent bonds

Boroxines are significant structures in the production of covalent organic frameworks, anion receptors, self-healing materials, and others. However, their utilization in aqueous media is a formidable task due to hydrolytic instability. Here we report a water-stable boroxine structure discovered from 2-hydroxyphenylboronic acid. We find that, under ambient environments, 2-hydroxyphenylboronic acid undergoes spontaneous dehydration to form a dimer with dynamic covalent bonds and aggregation-induced enhanced emission activity. Intriguingly, upon exposure to water, the dimer rapidly transforms into a boroxine structure with excellent pH stability and water-compatible dynamic covalent bonds. Building upon these discoveries, we report the strong binding capacity of boroxines toward fluoride ions in aqueous media, and develop a boroxine-based hydrogel with high acid–base stability and reversible gel–sol transition. This discovery of the water-stable boroxine structure breaks the constraint of boroxines not being applicable in aqueous environments, opening a new era of researches in boroxine chemistry.

Fluorescent Polymeric Sensor for Selective and Sensitive Detection of Cu(II) ions in Aqueous Medium

In our study, a selective and sensitive determination method was developed for Cu(II) ions by spectrofluorimetry. For this purpose, a polymeric membrane was prepared to determine Cu(II) ions by curing crosslinkers, functional monomers, and photoinitiators under UV light. The membrane was characterized, and the optimum conditions for determining Cu(II) ions were systematically investigated. The detection was performed at pH 5.0 in as little as 20 seconds at excitation and emission wavelengths of 376 nm and 455 nm, respectively. The linear range was 7.86.10-9-1.57.10-7 mol/L, and the method's detection limit was 2.24.10-9 mol/L. In addition, the sensor's repeatability, stability, and life were examined, and recovery studies were conducted. As a result, the developed method has been successfully applied to wastewater samples as a real sample. In addition, determining Cu(II) ions at low concentrations can be done quickly, reliably, and with high selectivity and sensitivity.

Ultra-hybrid sensor based on magnetic and fluorescent biomaterial for the sensitive/selective detection of toxic Ag+ and Hg2+ ions in real samples

The development of high-performance, eco-friendly and magnetic sensors prepared from natural products have recently attracted a lot of attention for the selective detection of metal ions in aqueous environments and the simultaneous detection of metals in the same environment. In this study, a fluorescent and magnetic sensor (MSp-P[5]-EN-B) was prepared by the immobilization of Bodipy and pillar [5]arene on the sporopollenin surface modified by Fe3O4 for the selective detection of Ag+ and Hg2+ ions separately and together in the aqueous solution. The characterization of the fluorescent and magnetic sensor, MSp-P[5]-EN-B, was supported by techniques such as SEM, FT-IR, and XRD. The fluorescence data of MSp-P[5]-EN-B sensor was examined with various concentrations in the range 1–100 μM that in here, an “on-off” fluorescence process for Ag+, and Hg2+ and the detection limits are 0.019 μM and 0.33 μM, respectively. As a result, the designed magnetic MSp-P[5]-EN-B sensor showed strong potential in terms of its accurate, sensitive, and practical application in the separate and simultaneous detection of Ag+ and Hg2+ ions in aqueous media.

A bifunctional fluorescent sensor based-on Pillar[5]arene for efficient detection of MnO4− as an oxidant and Hg2+ ion in aqueous media: Bio-imaging in living cells

The high amounts of oxidants and heavy metal ions caused undesirable health results and the detection of these ions gained increasing importance with new techniques. This paper focuses on a fluorescent macrocyclic sensor based on Pillar[5]arene and Bodipy (Bodipy-P[5]arene) for the recognition of oxidants and heavy metal ions in aqueous solution. After the characterization of the macrocyclic ligand, the spectroscopic measurements were carried out by Uv–vis and fluorescence spectroscopies. The bifunctional fluorescent macrocycle, Bodipy-P[5]arene, presents to a dual effect with fluorescence quenching response for fluorometrically recognizing MnO4- and Hg2+ ions. Bodipy-P[5]arene has low detection limits of MnO4- and Hg2+ such as 1.15 × 10-7 M and 8.12 × 10-7 M, respectively. Moreover, both Bodipy-P[5]arene can respectively detect the target ions in acidic and basic mediums and the macrocyclic ligand has short response times. In addition, the Bodipy-P[5]arene probe demonstrates low cellular toxicity and exceptional membrane permeability, making it a successful tool for fluorescently imaging Hg2+ and MnO4- ions within living HeLa cells.

Optical Chemosensors Synthesis and Appplication for Trace Level Metal Ions Detection in Aqueous Media: A Review.

In recent years, the development of optical chemosensors for the sensitive and selective detection of trace level metal ions in aqueous media has garnered significant attention within the scientific community. This review article provides a comprehensive overview of the synthesis strategies and applications of optical chemosensors dedicated to the detection of metal ions at low concentrations in water-based environments. The discussion encompasses a wide range of metal ions, including but not limited to heavy metals, transition metals, and rare earth elements, emphasizing their significance in environmental monitoring, industrial processes, and biological systems. The review explores into the synthesis methodologies employed for designing optical chemosensors, discovering diverse materials like organic dyes, nanoparticles, polymers, and hybrid materials. Special attention is given to the design principles that enable the selective recognition of specific metal ions, highlighting the role of ligand chemistry, coordination interactions, and structural modifications.Furthermore, the article thoroughly surveys the analytical performance of optical chemosensors in terms of sensitivity, selectivity, response time, and detection limits. Real-world applications, including water quality assessment, environmental monitoring, and biomedical diagnostics, are extensively covered to underscore the practical relevance of these sensing platforms. Additionally, the review sheds light on emerging trends, challenges, and future prospects in the field, providing insights into potential advancements and innovations. By synthesizing the current state of knowledge on optical chemosensors for trace level metal ions detection. The collective information presented herein not only offers a comprehensive understanding of the existing technologies but also inspires future research endeavors to address the evolving demands in the realm of trace metal ion detection.

Detection of TNP and sulfite ions in an aqueous medium using a pyrazinium-based chemosensor

A pyrazinium-based fluorescent chemosensor exhibited effecient detection of TNP and sulfite ions in aqueous medium. The chemosensor with a visually detectable color change in the presence of sulfite was integrated with a smartphone.

A near-infrared (NIR) organic probe for rapid naked-eye detection of fluoride ions in aqueous medium.

A dihydroxy-substituted tricyanopyrroline-based near-infrared (NIR) colorimetric probe (TCP-34Hy) is developed for the effective detection of fluoride ions in aqueous medium in the presence of Ca2+ ions. The naked-eye detection (drastic color change) selectively makes the NIR colorimetric sensor more efficient. The probe can detect fluoride ions from inorganic sources (NaF/KF) as well as organic sources (TBAF) in water. The water samples from different sources, such as tap, pond, river, and sewage, have been tested successfully for fluoride ion detection using the probe (TCP-34Hy). Investigations of different kinds of soil samples (clay soil, red soil, and river sand) after pre-treatment with NaF are also productive for detection of fluoride ions in water. The probe can also detect fluoride ions in toothpaste in aqueous medium. The role of Ca2+ is discussed and explained on the basis of experimental results. Additionally, the probe (TCP-34Hy) shows high selectivity towards fluoride ion detection with a LOD of 2.3 μM (0.052 ppm) in aqueous medium.

Three new AIE-cored luminescent Cd-based MOFs with high quantum yields and selective detection of ions in aqueous media

Three novel AIE-cored Cd-LMOFs are prepared with high IQYs and can be used in phosphors materials and fluorescent chemical sensors. Moreover, LMOF-3 is the first reported LMOF material for detecting Na+ with a detection limit of 1.90 × 10−5 M.