Organo-aqueous Medium Research Articles

Chromogenic Chemosensor for Simultaneous Detection of PO4 3- and CO3 2- Anions in Organo-Aqueous Solutions: Application in Arduino Based Electronic Color Sensor Device and Logic Gate.

Three new chromogenic receptors have been synthesized with the primary objective of facilitating the selective recognition of PO4 3-and CO3 2- ions in an organo-aqueous medium. R1 and R2 exhibit an extraordinary detection limit aligning with both EPA and WHO guidelines. R1 shows LOD of 0.135 ppm for PO4 3- and 0.175 ppm for CO3 2-, while R2 sets forth a LOD of 0.427 ppm for PO4 3- and 0.729 ppm for CO3 2-. The binding mechanism involves intramolecular charge transfer (ICT) band are substantiated by comprehensive studies that include UV-Vis titration, 1H-NMR titration, DFT studies and electrochemical studies. Chemosensors were employed in the formulation of logic gate, the fabrication of a paper strip test kit and its application in RGB color sensor device.

Colorimetric differentiation of arsenite and arsenate anions using a bithiophene sensor with two binding sites: DFT studies and application in food and water samples.

Chemosensor N7R1 with two acidic binding sites was synthesized, and the ability of the sensor to differentiate arsenite and arsenate in the organo-aqueous medium was evaluated using colorimetric sensing methods. N7R1 distinguished arsenite with a peacock blue color and arsenate with a pale green color in a DMSO/H2O (9 : 1, v/v) solvent mixture. The specific selectivity for arsenite was achieved in DMSO/H2O (7 : 3, v/v). The sensor demonstrated stability over a pH range of 5 to 12. The computed high binding constant of 9.3176 × 1011 M-2 and a lower detection limit of 11.48 ppb for arsenite exposed the chemosensor's higher potential for arsenite detection. The binding mechanism with a 1 : 2 binding process is confirmed using UV-Vis and 1H NMR titrations, electrochemical studies, mass spectral analysis and DFT calculations. Practical applications were demonstrated by utilizing test strips and molecular logic gates. Chemosensor N7R1 successfully detected arsenite in real water samples, as well as honey and milk samples.

Exploring organo-bentonite adsorption properties for biphenyl removal from organic-aqueous media: kinetic study and industrial perspective

Biphenyl, a frequently encountered and resilient compound in wastewater, proves resistant to conventional treatment methods because of its enduring nature. It forms the structural basis for persistent organic pollutants such as PCBs. In this study, we explored the adsorption of biphenyl in an organo-aqueous medium using both natural (Bent) and organomodified (CTAB-Bent) bentonite clay. Our objective was to highlight its potential for biphenyl wastewater treatment. We analyzed the physicochemical and textural properties of these clays through FTIR, XRF, XRD, SEM, BET method, and Zeta potential measurements. Impressively, these materials exhibited remarkable biphenyl adsorption capacity under acidic conditions, with Bent achieving 60% removal and CTAB-Bent an impressive 91%. We investigated the adsorption kinetics using first-order and pseudo-second-order models and assessed isotherm data with the Langmuir, Freundlich, and Langmuir-Freundlich (sips) equations. The Langmuir model, at pH 3, proved optimal, with high accuracy (R²) and minimal error (RMSE) values (0.997 and 1.20, respectively). Clay nature significantly influenced pollutant uptake efficiency, confirming the efficacy of the selected bio-based clay. We propose a protocol adaptable for industrial-scale applications.

Colorimetric chemosensors for the selective detection of arsenite over arsenate anions in aqueous medium: Application in environmental water samples and DFT studies

Novel organic receptors N3R1- N3R3 were developed for the selective colorimetric recognition of arsenite ions in the organo-aqueous media. In the 50% aq. acetonitrile media and 70% aq. DMSO media, receptors N3R2 and N3R3 showed specific sensitivity and selectivity towards arsenite anions over arsenate anions. Receptor N3R1 showed discriminating recognition of arsenite in the 40% aq. DMSO medium. All three receptors formed a 1:1 complex with arsenite and stable for a pH range of 6–12. The receptors N3R2 and N3R3 achieved a detection limit of 0.008 ppm (8 ppb) and 0.0246 ppm, respectively, for arsenite. Initial hydrogen bonding on binding with the arsenite followed by the deprotonation mechanism was well supported by the UV–Vis titration, 1H- NMR titration, electrochemical studies, and the DFT studies. Colorimetric test strips were fabricated using N3R1- N3R3 for the on-site detection of arsenite anion. The receptors are also employed for sensing arsenite ions in various environmental water samples with high accuracy.

Chromogenic detection of fluoride, dihydrogen phosphate, and arsenite anions based on 2,4-dinitrophenyl hydrazine receptors: spectral and electrochemical study

ABSTRACT The colorimetric recognition of biologically relevant fluoride (F−), acetate (AcO−), and dihydrogen phosphate (H2PO4 −) ions, and poisonous arsenite (AsO2 −) ions, was devised and new receptors for these anions synthesised via the Schiff base condensation procedure. UV–visible titration, fluorescence titration, 1H-NMR titration, and cyclic voltammetry were used to explore the interactions of receptors R1–R3 with anions and possible detection mechanisms. The synthesised probes could sense inorganic fluoride, acetate, dihydrogen phosphate, and arsenite in the organo–aqueous medium (H2O/ Dimethylsulphoxide, 1: 9, v/v) and displayed a change in colour detectable to the naked eye. Out of the three synthesised receptors, receptor R1 showed better sensing ability of fluoride, acetate, dihydrogen phosphate, and arsenite ions in the organo–aqueous medium with a lower detection limit of 0.1 ppm, 0.171 ppm, 0.194 ppm, and 0.144 ppm, respectively. All three receptors formed complexes with the anions through H-bonding interaction followed by deprotonation of the NH proton.

One-step fabrication of new generation graphene-based electrodes for polymer electrolyte membrane fuel cells by a novel electrophoretic deposition

High Pt loading has better tradeoff in polymer electrolyte membrane fuel cell (PEMFC) in terms of improved performance and operational longevity. But, to employ low amounts of Pt electrocatalysts via an alternative carbon-based support and utilization technique is vital. This study presents the use of a one-step novel technique, an electrophoretic deposition (EPD) method, through which reduced graphene oxide (rGO) supported Pt nanoparticles have been directly fabricated onto carbon paper to form electrodes for PEMFC. Our process involves simultaneous synthesis and deposition of Pt-reduced GO nanocomposites onto oxygen plasma pre-treated carbon paper in an organo-aqueous media at various deposition time. Through this technique, homogenously distributed Pt nanoparticles ranging from 5 to 6 nm in size on graphene support were successfully synthesized to form catalyst layer on carbon paper. The characteristics of fabricated electrodes were investigated ex-situ by Raman spectroscopy, FE-SEM, XPS, ICP, FIB, TEM. Furthermore, catalytic activity towards hydrogen oxidation reaction was evaluated via CV measurements and fuel cell performance tests were also conducted. The highest ECSA value of 27.4 m2g-1 and the Pt utilization efficiency of 1.48 kW/gPt−1 were achieved at an optimized Pt loading of 0.129 mg cm−2. A maximum power density of 280 mW cm−2 was obtained with increasing EPD time and Pt precursor concentration at the same time. The achieved results are attributed to the dispersion of Pt nanoparticles on rGO nanosheets displaying synergetic performance as catalyst necessary for PEMFCs, thanks to the EPD technique's viability, ease in handling, and reproducibility in the synthesis route. In the previous studies on Pt/GO based fuel cell electrodes by EPD, on one hand, Pt NPs were synthesized on GO by chemical methods first and electrodes were fabricated by a subsequent EPD. On the other hand, the fuel cell performances of those electrodes have been rarely shown. To the best of our knowledge, this is the first time in literature not only about the use of EPD technique for the fabrication of fuel cell electrodes in one-step but also the evaluation of fuel cell performance of the electrodes fabricated by EPD.

Spectroscopic studies of colorimetric receptors for detection of biologically important inorganic F−, AcO− and H2PO4− anions in organo-aqueous medium: Real-life application

Two new 4-nitrobenzylidene based receptors 2-((E)-(((E)-4-nitrobenzylidene) hydrazono) methyl)-1H-indole (R1) and 2-((E)-(((E)-4-nitrobenzylidene)hydrazono)methyl)-1H-pyrrole (R2) have been designed and synthesized by the simple condensation reaction and characterized by using spectroscopic techniques. The receptors exhibited high sensitivity and selectivity towards biologically important anions such as F−, AcO− and H2PO4− in DMSO and sodium salts F−, AcO− and H2PO4− in aqueous medium (9:1 v/v, DMSO: H2O). The receptors R1 and R2 dispensed high sensitivity towards sodium arsenite and detection limit were found to be 0.143 ppm and 0.32 ppm in (9:1 v/v, DMSO: H2O) reflect the stable complex formation of the receptor with AsO2− ion in aqueous medium. 1H NMR titration carried out to understand the nature of interaction between receptor R1 and F− ion. Cyclic voltammetric studies performed for receptors R1 and R2 in DMSO exhibited shift in oxidation and reduction peak with addition of basic F− ion signifying strong interaction between receptors and anions. Interesting, receptor R1 exhibited high selectivity for AcO− ion in the different range of pH from (6–11). Furthermore, receptor R1 and R2 showed colorimetric sensing of F− and AcO− ion present in commercially available toothpaste and vinegar in the form of Na+F− and Na+AcO− in aqueous medium.

Fluorescent chemosensor for lethal cesium detection using thin film membrane

ABSTRACTTwo new simple fluoroionophores viz. L1 and L2 were synthesized and characterized. These two fluoroionophores were shown to be sensitive and selective for Cs+ among the 12 metal ions in organic HEPES buffer medium by absorption and fluorescence. An attractive glowing green and blue color emission were observed in the presence of Cs+ for L1 and L2.The fluoroionophores were found to be as an effective fluorescence chemosensors for Cs+ ions with the detection limit of 0.03 ppm and 0.49 ppm, respectively. In order to evaluate the chemosensor activity in organo-aqueous medium, organic thin films (OTFs) and TLC kits of fluoroionophores viz. L1 and L2 were formed using physical coating method.

Dansyl-appended CuII-complex-based nitroxyl (HNO) sensing with living cell imaging application and DFT studies.

We introduce herein, a novel copper complex-based fluorescent probe [CuII(DQ468)Cl]+ that exhibits a significant fluorescence turn-on response towards nitroxyl (HNO) with high selectivity over other biological reactive oxygen, nitrogen and sulfur species, including nitric oxide (NO). A smart strategy, involving HNO-induced reduction of paramagnetic [CuII(DQ468)Cl]+ to diamagnetic [CuI(DQ468)]+ with concomitant fluorescence enhancement via a PET mechanism is focused here. This reduction-based strategy was also supported by X-band EPR response and mass spectroscopy. The metal free probe (DQ468) showed high affinity towards Cu2+ to form [CuII(DQ468)Cl]+ with a 0.091 μM detection limit, which subsequently enabled the detection of HNO in an organo-aqueous medium at biological pH (7.4) in the green wavelength region (λem = 543 nm) with a LOD of 0.41 μM. The ground-state geometries of DQ468, [CuII(DQ468)Cl]+ and [CuI(DQ468)]+ were optimized by DFT calculations, which revealed that the central metal ion in [CuII(DQ468)Cl]+ is in a distorted tetrahedral geometry with the C1 point group. Additionally, the negligible cytotoxicity and good biocompatibility make the developed probe useful for the in vitro detection of HNO.

A rhodamine hydrazide–4-nitroindole-3-carboxaldehyde based turn on Hg2+ chemosensor: cytoplasmic live cell imaging, logic gate and memory device applications and computational studies

A new, highly sensitive probe L2 for the selective detection of Hg2+ in organo-aqueous (H2O:CH3CN, 1:1, v/v, HEPES buffer, pH 7.2) medium has been synthesized from rhodamine 6G-hydrazide and 4-nitroindole-3-carboxaldehyde. It was thoroughly characterized by physicochemical techniques including single crystal X-ray diffraction studies. The reaction of L2 with Hg2+ gives a 1:1 stoichiometry resulting in a 146 fold fluorescence enhancement and a binding constant (Kf) of 3 × 104 M−1. The spirolactam form of the probe is non-fluorescent; however, it shows dual channel (absorbance and fluorescence) recognition of Hg2+ via CHEF effect through the opening of the spirolactam ring. The quantum yields of L2 (0.00045) and L2-Hg2+ (0.29) show the higher stability of complex in the excited state over the free ligand. The 44.5 nM LOD value demonstrates the detection of Hg2+ at a very low concentration range. Cell imaging studies show the cytoplasmic recognition of Hg2+ by L2. Experimental results are comparable with theoretical values obtained by DFT studies. The fluorescence emission of the complex was completely quenched by I- and from the reversibility studies an advance level INHIBIT logic gate and memory device can be framed.

Aminophenol based colorimetric chemosensor for naked-eye detection of biologically important fluoride and acetate ions in organo-aqueous medium: Effective and simple anion sensors

Three new novel colorimetric receptors (R1-R3) based on aminophenol have been designed and synthesized by simple Schiff base reaction and their anion sensing properties were examined, characterized by common spectroscopic techniques such as FT-IR, UV–visible, 1HNMR,13CNMR, ESI–MS and fluorescence. Receptors R1 and R2 bearing −OH group at ortho and para position acting as anion binding sites with NO2 moiety as an optical signaling unit. Receptors R1 and R2 elevated selective and sensitive ability towards F− and AcO− ions over the other competing anions in DMSO as well as in CH3CN. Receptors R1 and R2 showed high capability of sensing acetate and fluoride ions present in the form of sodium salts such as NaAcO and NaF in an aqueous medium. The color of both the receptors R1 and R2 solution changes from pale green to blue and pale yellow to peach color with the addition of sodium salts of acetate (NaAcO) and fluoride (NaF) with a bathochromic shift of 168 nm and 165 nm in the UV–vis absorption spectra of receptor R1 and 103 nm and 100 nm in case of receptor R2 due to ICT transition between the electron rich −OH and electron deficient NO2 moiety. Moreover, receptors R1-R2 showed noteworthy fluorescence enhancement, response towards F− and AcO− ion in DMSO. Compared to receptor R2, R1 shows a huge red shift towards F− and AcO− ions in organo-aqueous medium due to the presence of −OH proton at ortho position which effectively bind with both the anions. The binding constant and stoichiometry of the receptors-anions complex was calculated by using Benesi-Hildebrand (B–H) plot. The anion binding properties of receptor R1 via ICT mechanism was enlightened by UV–vis titration, 1HNMR studies.

A novel three-input monomolecular logic circuit on a rhodamine inspired bio-compatible bi-compartmental molecular platform

Methodological synthesis of a new biocompatible bi-compartmental rhodamine based probe (L3) provides a multi-inputs and multi-outputs molecular logic circuit based on simple chemosensing phenomena. Spectroscopic responses of Cu2+ and Hg2+ towards L3 together with reversible binding of S2- with L3-Cu2+ and L3-Hg2+ complexes help us to construct a thee-input molecular circuit on their control and sequential addition to a solution of L3 in a mixed organo-aqueous medium. We have further successfully encoded binary digits out of these inputs and outputs which may convert a three-digit input string into a two-digit output string resulting a simple monomolecular logic circuit. Such a molecular ‘Boolean’ logic operation may improve the complexity of logic gate circuitry and computational speed and may be useful to employ in potential biocompatible molecular logic platforms.

New sensitive and selective calixarene-based fluorescent sensors for the detection of Cs+ in an organoaqueous medium

A calixarene-based fluorescent sensor has been designed for the detection of Cs+ in the micromolar range.

Benzthiazole-derived chromogenic, fluorogenic and ratiometric probes for detection of hydrazine in environmental samples and living cells

Abstract Benzothiazole-based chromogenic and ratiometric fluorescent chemodosimetric probes CD1 and CD2, were synthesized and characterized. The probes are designed in such a way that the excited state intramolecular proton transfer (ESIPT) of the benzothiazole moiety gets blocked. Upon treatment with hydrazine in organo-aqueous medium[DMSO: H2O; 2:1 (v/v)] at physiological pH, the aectyl protective group of probes CD1 and CD2 were removed readily in presence hydrazine and ESIPT of the probes were switched on, which resulted remarkable photo-physical changes. These two ESIPT–based ratiometric fluorescent probes were shown to be selective and sensitive for hydrazine among different cations, anions and amines studied in organo-aqueous medium[DMSO: H2O; 2:1 (v/v)] at physiological pH, by fluorescence, absorption, and visual emission color change. These key features allows the two probes to be employed for hydrazine detection by simple visual inspection. DFT and TDDFT calculations were performed in order to demonstrate the sensing mechanism and the electronic properties of probe and hydrazinolysis product. An easy-to-prepare test strips, obtained by dipping the TLC plates into the solution of CD1 and CD2, were able to detect hydrazine in practical samples. Moreover, the utility of the probes CD1 in showing the hydrazine recognition in live cells has also been demonstrated using Vero cells as monitored by fluorescence imaging.

Highly Selective Sensing of Li+ in H2O/CH3CN via Fluorescence ‘Turn-on’ Response of a Coumarin-Indole Linked Dyad: an Experimental and Theoretical Study

A coumarin-indole dyad, N-((7-hydroxy-2-oxo-2H-chromen-4-yl)methyl)-1H-indole-2-carboxamide has been synthesized and characterized by 1H-NMR and 13C-NMR. Effect of various metal ions on fluorescent behavior was also studied. The synthesized compound showed remarkable specificity towards Li+ in organo-aqueous medium over other metal ions. Coordination of the compound with Li+ induces a turn-on fluorescence response. The sensor exhibited good binding constant and low detection limit towards Li+. Experimental results have been verified with Density Functional Theory and Time Dependent Density Functional Theory calculations.

Design and synthesis of a new organic receptor and evaluation of colorimetric anion sensing ability in organo-aqueous medium

A new organic receptor has been designed and synthesized by the combination of aromatic dialdehyde with nitro-substituted aminophenol resulting in a Schiff base compound. The receptor exhibited a colorimetric response for F− and AcO− ion with a distinct color change from pale yellow to red and pink respectively in dry DMSO solvent and yellow to pale greenish yellow in DMSO:H2O (9:1, v/v). UV–Vis titration studies displayed a significant shift in absorption maxima in comparison with the free receptor. The shift could be attributed to the hydrogen bonding interactions between the active anions and the hydroxyl functionality aided by the electron withdrawing nitro substituent on the receptor. 1H NMR titration and density functionality studies have been performed to understand the nature of interaction of receptor and anions. The lower detection limit of 1.12ppm was obtained in organic media for F− ion confirming the real time application of the receptor.

A colorimetric and turn-on fluorescent chemosensor for selective detection of Hg2+: theoretical studies and intracellular applications

A new colorimetric, “turn-on” fluorescent chemosensor (DEAS-BPH) was synthesized for selective and sensitive recognition of Hg2+ ions with no interference from environmentally relevant metal ions in a mixed organo-aqueous medium.

A pyrene thiazole conjugate as a ratiometric chemosensor with high selectivity and sensitivity for tin (Sn4+) and its application in imaging live cells

A new pyrene thiazole-conjugate amine based fluoroionophore, PTC was developed for ratiometric detection of Sn4+ ion in organo-aqueous medium.

ChemInform Abstract: Coupling Reactions in Water

AbstractReview: 615 refs.

Highly Selective and Sensitive Phosphane Sulfide Derivative for the Detection of Hg2+ in an Organoaqueous Medium

A new fluorescent molecular sensor for Hg2+ based on the phosphane sulfide derivative exhibits a very low detection limit in an aqueous medium (3.8 nM) with a very high selectivity over other interfering cations. The reversibility of the complexation process was also examined and was found to be successful. [structure: see text]