μM For Fe3 Research Articles

Synthesis of ruthenium-doped molybdenum disulfide quantum dots for Fe3+ detection

This research successfully achieved a high-efficiency synthesis of Ruthenium-doped molybdenum disulfide quantum dots (Ru-MoS2 QDs) with a yield of 27 wt%. The obtained Ru-MoS2 QDs possess blue fluorescence and quantum yield of 2.56 %. Moreover, these Ru-MoS2 QDs demonstrated exceptional selectivity and an impressively low detection limit of 0.55 μM for Fe3+ ions, highlighting their considerable promise for future applications in sensitive detection methodologies.

Synthesis of shape-controlled covalent organic frameworks for light scattering detection of iron and chromium ions

Fabricating covalent organic frameworks with different morphologies based on the same structural motifs is both interesting and challenging. Here, a TTA-TFP-COF was synthesized by both solvothermal and room temperature methods, with 2,4,6-Tris(4-aminophenyl)-1,3,5-triazine (TTA) and 1,3,5-tris(4-formylphenyl)-benzene (TFP) as raw material. Using different synthesis conditions and adding aniline and benzaldehyde as regulators in the synthesis process, we found that these processes could slow down the reaction speed, increase the exchange and metathesis reactions of dynamic reversible reactions, and improve the reversibility of the reaction system. Thus, controllable synthesis of TTA-TFP-COF with different morphologies, including micro-particles, hollow tubes with controllable diameters, and micro-flowers was achieved. Our further study found that metal ions, Fe3+ and Cr3+ ions, could coordinate with N and O in TTA-TFP-COF and partially destroy the structure of TTA-TFP-COF. The particle size of the TTA-TFP-COF became smaller, thus resulting in the decrease of the light scattering intensity of the COF. An excellent linear relationship exists between the light scattering changes (ΔI) and metal ions concentration (c) from 2.0 to 350.0 μM for Fe3+ and 40.0–800.0 μM for Cr3+, respectively. Thus, rapid and selective analytical methods for detecting metal ions were developed by TTA-TFP-COF here.

Multicolor nitrogen-doped carbon quantum dots and its application in the detection of Fe3+ ion.

In this paper, nitrogen-doped carbon quantum dots (N-CQDs) are synthesized by the hydrothermal method. N-CQDs exhibit strong fluorescence, and N-CQDs are well dispersed in water as well as in various organic solvents. N-CQDs emit multi-color fluorescence from blue to red, with wavelengths in the range of 450-650 nm without the need for purification. Furthermore, the fluorescence emission of N-CQDs was selectively quenched after adding Fe3+ ions. N-CQDs were used as a nanoprobe for the detection of Fe3+ ions, showing a good linear correlation between the fluorescence emission and the concentration of Fe3+ in the Fe3+ concentration range from 0 to 100 μM. The limit of detection (LOD) was 55.7μM for Fe3+ in water and 40.2μM in fetal bovine serum (FBS) samples. The study shows that the synthesized N-CQDs have low cost and great potential for application in biological analysis.

Rapid, low-cost determination of Hg2+, Cu2+, and Fe3+ using a cellulose paper-based sensor and UV–vis method with silver nanoparticles synthesized with S. mammosum

As water effluents are often highly contaminated with metals, having a quick and cost-effective method of analysis is crucial. This study used the supernatant derived from the green synthesis of silver nanoparticles (AgNPs) with Solanum mammosum to detect mercury, copper, and iron with a low-cost cellulose paper-based sensor and a rapid colorimetric method applying ultraviolet–visible spectroscopy (UV–Vis). AgNPs in two precursor concentrations using silver nitrate, 1 mM (17.4 ± 9 nm) and 50 mM (and 22 ± 8.1 nm), were utilized to assess the efficacy of the analysis and removal of Hg2+, Cu2+, and Fe3+ from contaminated water. Cellulose paper-based sensor showed limits of detection (LODs) for Hg2+ of 2.46 and 123 μM using AgNPs at concentrations of 1 and 50 mM, respectively. For Cu2+, the LODs were 55 and 2750 μM, and for Fe3+, the LODs were 49 and 2470 μM using the respective concentrations. To differentiate and detect the cations with the naked eye, a potassium iodide and potassium ferrocyanide (1:1) aqueous solution was used, producing a yellow, pink, and blue color for Hg2+, Cu2+, and Fe3+, respectively. Additionally, the titration curves of Hg2+, Fe3+, and Cu2+ were examined by UV–Vis using the supernatant liquid. The LODs for the UV–Vis method using AgNPs at a concentration of 1 mM were 1.50 μM for Hg2+, 10.7 μM for Cu2+, and 4.33 μM for Fe3+, while the LODs for AgNPs at 50 mM were 5.75, 27.6, and 15 μM for Hg2+, Cu2+, and Fe3+, respectively. Furthermore, these nanoparticles were utilized to assess the efficacy of the removal of Hg2+, Cu2+, and Fe3+ from contaminated water. Removal efficiency with the solid 50 mM AgNPs was analyzed via flame absorption spectrophotometry; values over 95% were obtained for the three ions. The results underscore the effectiveness of a green synthesis approach to generating AgNPs, enabling efficient and economical cation analysis and water decontamination.

Green synthesis of copper nanoclusters using Cissus quadrangularis leaves extract and cysteine as cooperative ligands for the detection of Fe3+ ion and 2,6-dipicolinic acid in biofluids via fluorescence turn off–on mechanism

An off–on fluorescent sensor is devised by using greenish-blue light-emitting Cissusquadrangularis-cysteine-CuNCs (C. quadrangularis-Cys-CuNCs) for the rapid, precise, and recognition ofFe3+ ion and 2,6-dipicolinic acid (DPA). The structure, size, surface functionalities and oxidation state of the elements present in C. quadrangularis-Cys-CuNCs are confirmed by high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopic and X-Ray diffraction (XRD) techniques. The as-synthesized C. quadrangularis-Cys-CuNCs exhibited λEm/Ex at491/370 nm. The fluorescence intensity ofC. quadrangularis-Cys-CuNCs was reduced selectively to 63 % by Fe3+, however it was restored with the addition of DPA. This method exhibited the limits of detection (LODs) of 0.125 and 0.38 μM for Fe3+ and DPA, respectively. The C. quadrangularis-Cys-CuNCs based fluorescence turn-off–on sensing platform showed remarkable performance for the analyses of Fe3+ ion and DPA in real samples, revealing great potentiality of the method for practical applications.

Solid-State Fluorescent Organic Polymers for Visual Detection and Elimination of Heavy Metals in Water.

Selective sensing and removal of toxic heavy metals from water are highly essential since their presence poses significant health and environmental hazards. Herein, we designed and synthesized a novel fluorescent nonconjugated organic polymer by strategically incorporating two key functional groups, namely, a dansyl fluorophore and dithiocarbamate (DTC). Different characterization techniques, including 1H nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR), and fluorescence spectroscopy, were performed to understand its structure and material properties. The quantum yield of 4.72% and its solid-state fluorescence indicate that it has potential for various applications in several technological and scientific domains. In this study, we investigated a specific application involving the detection and elimination of heavy metals from water. Interestingly, the presence of dansyl and DTC moieties demonstrated remarkable selectivity toward Cu2+, Co2+, Ni2+, Fe3+, and Fe2+ sensing, displaying distinct color changes specific to each metal. Cu2+ resulted in a yellow color, Co2+ showed a green color, Ni2+ displayed a pale yellowish-green color, and Fe2+/Fe3+ exhibited a brown color. The LOD (limit of detection) for each metal was obtained in the nanomolar range by using a fluorescence spectrometer and the micromolar range from UV-visible spectra: 13.27 nM and 0.518 μM for Cu2+, 8.27 nM and 0.581 μM for Co2+, 14.36 nM and 0.140 μM for Ni2+, 14.95 nM and 0.174 μM for Fe2+, and 15.54 nM and 0.33 μM for Fe3+. Moreover, the DTC functionality on its backbone facilitates effective interaction with the aforementioned heavy metals, subsequently removing them from water (except Fe2+ and Fe3+), validating its dual functionality as both an indicator and a purifier for heavy metals in water. The polymer exhibited a maximum adsorption capacity of 192.30 mg/g for Cu2+, 159.74 mg/g for Co2+, and 181.81 mg/g for Ni2+. Furthermore, this approach exhibits versatility in crafting fluorescent polymers with adjustable attributes that are suitable for a wide range of applications.

A quinazolinone based optical probe for the simultaneous determination of Fe3+and Cu2+ content in aqueous samples; An experimental and theoretical investigations

The chemosensor “3-((1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)amino)-2-(4-(4-methylpiperazin-1-yl)phenyl)-2,3-dihydroquinazolin-4(1H)-one”, referred as “probe” was synthesized for the accurate quantification of Fe3+ and Cu2+ ions in various prepared samples originated from petroleum crude oil, catalyst, milk, and water. This probe serves as a naked-eye chemosensor, displaying distinct color changes in an aqueous medium, transitioning from light yellow to dark brown for Fe3+ and pale green for Cu2+ions. Remarkably, it displays exceptional dual selectivity for Fe3+ and Cu2+ ions, even in the presence of potentially interfering elements such as Na+, K+, Ca2+, Mg2+, Ba2+, Cr3+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+, As3+, Sn2+, and Hg2+. Experimental assessments demonstrated the probe's high sensitivity, detecting concentrations as low as 0.017 µM for Fe3+ ions and 0.014 µM for Cu2+ ions. The 1:1 binding interaction between the probe and the metal ions was established through Job's plot, thermogravimetric analysis, and elemental analysis. Computational experiments were performed to determine the optimal geometry of the probe and its iron & copper complexes, revealing an octahedral geometry for both complexes. A comparative quantification analysis of Fe3+ and Cu2+ content across diverse aqueous samples was executed using both ICP OES and a new method. Notably, the results exhibited a favorable concordance with ICP OES outcomes, affirming the practical viability of these novel techniques for a wide range of samples.

Fluorometric Determination of Fe3+ Ions using Carbon Dots Prepared from the Extract of Singapore Cherry

Background: The development of affordable and ecologically acceptable technologies for heavy metal detection and removal is required due to the rising levels of water and soil pollution. Carbon Dots (CDs) have emerged as a promising nanomaterial for heavy metal detection due to their unique properties. In this study, we report a simple and eco-friendly method to produce CDs using Muntingia calabura fruit extract as a precursor. Methods: The hydrothermal method produced a well-defined size, structure, and optical properties of CDs, which were analyzed by using various characterization techniques, including Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), Elemental mapping (E-map), UV-visible spectroscopy, X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Photoluminescence (PL) spectroscopy, and Transmission Electron Microscopy (TEM). Additionally, Zeta potential and DLS analysis were used to characterize the CDs. Results: As-synthesized CDs exhibited strong fluorescence emission, making them suitable for the selective determination of Fe3+ ions. The detection limit was found to be 3.6 μM for Fe3+ ions, which highlighted the potential application of as-prepared CDs in environmental monitoring. Conclusion: The green synthesized CDs from Muntingia calabura fruit extract provided a sustainable approach for developing efficient nanoprobes for detecting Fe3+ ions in environmental and biological samples.

Chromolaena Odorata Leaves Derived Carbon Dot‐Based Fluorescence/Second‐Order Scattering Ratiometric Sensor for Fe3+ and Vitamin C

Herein, a ratiometric fluorescence and second‐order scattering sensor with plant leaf‐derived carbon dots (CDs) for Fe3+ and vitamin C is reported. The CDs are prepared from Chromolaena odorata leaves through a one‐pot hydrothermal method. The synthesized CDs have a quantum yield of 22.6%. The spherical dots have an average size of 3 nm and the chemical composition is found as nitrogen (7%) being the highest heteroatom present along with carbon and oxygen atoms in it. The ratio between fluorescence intensity at 445 nm and second‐order scattering constitutes the sensor output. A linear relationship is found between the output and analyte concentration in the range 0–70 and 0–10 μM with limit of detection 0.12 and 1.2 μM for Fe3+ and vitamin C, respectively. Static mechanism along with inner filter effect has been identified as the underlying quenching mechanism for Fe3+ activity. The strong chelation of Fe3+ by vitamin C further enhances the fluorescence. The change in the second‐order scattering intensity is explained by the formation and disruption of CDs/Fe3+ complex. The sensor also shows satisfactory performance with borewell water (Fe3+) and commercial tablet (vitamin C) with recovery rate ranging between 98.6% and 103.5%.

Two trinuclear cluster metal–organic frameworks: syntheses, structures, highly fluorescent sensing and magnetic properties

Two new metal–organic frameworks [Zn3(TCPB)2(H2O)2]·3DMF·2H2O (1) and [Mn1.5(TCPB)(DMF)(H2O)]·DMF(2)(H3TCPB = 1,3,5-tri(4-carboxyphenoxy)benzene), have been successfully constructed by solvothermal methods and structurally characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, Raman spectra, 1H NMR spectra, powder X-ray diffraction and thermogravimetric analyses. Single-crystal X-ray diffraction analyses reveal that complex 1 crystallizes in the trigonal space group P3¯ 1c and possesses a 2D network, whereas complex 2 crystallizes in the triclinic space group P1¯ and also possesses a 2D network. TOPOS analyses reveal that both complexes 1 and 2 have a (3,6)-connected network topology with the Schläfli symbol of (43·612) (43)2 for 1 and {43}2{46·66·83} for 2. Notably, further investigation indicates that complex 1 can be employed as a bi-functional fluorescent sensor for highly sensitive and selective detection of ferric ions (Fe3+) and 2,4,6-trinitrophenol (TNP), with the detection limit of 0.11 μM for Fe3+ and 0.14 μM for TNP. Furthermore, the possible fluorescence quenching mechanisms are explained as: (a) photo-induced electron transfer (PET) caused by the HOMO-LUMO energy gap through DFT and (b) fluorescence resonance energy transfer (FRET). Besides, the magnetic property measurement indicated that complex 2 shows antiferromagnetic interactions between trinuclear {Mn3(COO)6} SBUs.

A novel ratiometric design of microfluidic paper-based analytical device for the simultaneous detection of Cu2+ and Fe3+ in drinking water using a fluorescent MOF@tetracycline nanocomposite.

The regular and on-site monitoring of ions in drinking water is essential for safeguarding public health, ensuring high water quality, and preserving the ecological balance of aquatic ecosystems. Thus, developing a portable analytical device for the rapid, cost-effective, and visual on-site detection of multiple environmental pollutants is notably significant. In the present work, a novel ratiometric microfluidic paper-based analytical device (μPAD) was designed and developed for the simultaneous detection of Fe3+ and Cu2+ ions in water samples taking advantages from built-in masking zone. The μPAD was functionalized with a greenish-yellow fluorescent Zn-based metal-organic framework@tetracycline (FMOF-5@TC) nanocomposite, and the ratiometric design was based on the change in emission color from greenish yellow (FMOF-5@TC) to blue (FMOF-5). The μPAD consisted of one sample zone linked to two detection zones via two channels: the first channel was for the detection of both ions, while the second was intended for detecting only Cu2+ ions and comprised a built-in masking zone to remove Fe3+ ions prior to reaching the detection zone. The corresponding color changes were recorded with the aid of a smartphone and RGB calculations. The linear ranges were 0.1-80 μM for Cu2+ and 0.2-160 μM for Fe3+, with limits of detection of 0.027 and 0.019 μM, respectively. The simple μPAD design enabled the simultaneous detection of Cu2+ and Fe3+ ions in drinking water samples with excellent accuracy and precision, with spike recoveries of 81.28-96.36% and 83.01-102.33% for Cu2+ and Fe3+, respectively.

A luminescent anionic Cadmium(II)-MOF for the detection of nitrophenol compounds and metal ions in an aqueous solution

An anionic MOF, namely, {(CH3)2NH2)2[Cd(µ4-PPTA)]·DMF·7H2O}n (1) was synthesized with 4,4′,4″,4‴-(1,4-phenylenbis(pyridine-4,2,6-triyl))tetrabenzoic acid (H4PPTA) and characterized. X-ray results showed that 1 had a four-fold interpenetrating 3D framework with dia topology and the charged balance was provided by dimethylamine cations in the framework. Due to the high emission property and stability of 1 in water, the luminescence detections of nitroaromatic compounds and metal ions were performed with 1. 1 could detect the nitrophenol compounds and metal ions in water via luminescence quenching. The detection limits were 6.84 µM for 4-nitrophenol (NP), 1.85 µM for 2,4-dinitrophenol (DNP) and 2.76 µM for 2,4,6-trinitrophenol (TNP) and 94.4 µM for Al3+, 66 µM for Cr3+, 18.3 µM for Fe3+ and 27.6 µM for Cu2+. The detections of the nitrophenol compounds by 1 were due to hydrogen bonding interaction and resonance energy transfer. Moreover, the detections of metal ions by 1 were assigned to competitive absorption and electrostatic interactions with the anionic framework.

Fluorescent turn-off sensor for Cu2+ and Fe3+ ions in 100% aqueous media with a biocompatible polymer

A sensitive analytical method using an acridinium derivative in 100% aqueous media to detect Cu (II) and Fe (III) ions been developed. The photophysical properties of a thiophene-phenylanilide-acridinium triad (TPA) in acidic poly(methylacrylic acid) (PMAA) solution are altered in the presence of various metal ions. While dye/PMAA mixtures in acidic condition emit strongly at around 540 nm, Fe3+ and Cu2+ ions can each quench the charge shift state (CSH) emission significantly. The linear range of response to Cu2+ is 1 to 9.0 μM and to Fe3+ is 4 to 68 μM. The detection limit is 0.11 μM for Cu2+ ions and 0.60 μM for Fe3+ ions. Stern-Volmer plots showed more than one quenching mechanism for Fe3+ ions and the Benesi-Hilderbrand plot indicates a 1:1 binding ratio between dye/PMAA mixture and metal ions. While Cd2+ and Hg2+ ions interfere with the quenching, addition of iodide ions completely resolves the interference problem for both ions. The quenching by Fe3+ ions involved the inner-filter effect and partial removal of dye molecules from the hydrophobic interior of PMAA due to competitive binding. The quenching by Cu2+ ions is likely due to photoinduced electron transfer from the charge shift state of dye molecules to the partly filled d-orbitals of Cu2+ ions, leading to weaker CSH emission. Computer simulation supports the model in which dye molecules incorporate into the hydrophobic pockets formed due to the coordination of Cu2+ ions with carboxyl groups on PMAA chains.

A Zn based two-dimensional metal-organic framework as a dual ion sensor in aqueous media.

Excess and shortage of some metal ions like Fe3+ ions in drinking water away from permissible levels can cause severe health threat. Similarly, chromium is found chiefly in a hexavalent form that also poses a threat to human health. Human beings and other living organisms are at greater risk of exposure to these toxic ions and other chemicals. Development of new, effective and fast sensors is the need of time. MOFs are nanoporous materials which have quite fast detection time and effective in sensing of various metal ions and hazardous chemicals. A Zn based two-dimensional is synthesized and applied for the sensing of Fe3+ and Cr2O72- ions. Due to the presence of free oxygen and nitrogen atoms, this MOF showed quite high sensitivity with Ksv value of 1.8×104 and 6.5×104 with a limit of detection (LOD) 2.5μM and 0.15μM for Fe3+ and Cr2O72-ions respectively. This study proved the two-dimensional MOF as excellent sensor for the detection of Fe3+ and Cr2O72- ions. This can be used as colorimetric sensor for these ions due to color changes visible to the naked eye.

Green synthesis of surface-group-tunable red emissive carbon dots and their applications for Fe3+ and pyrophosphate detection

Red emission carbon dots (R-CDs) have great potential applications in optical and electronic devices, but few studies have focused on synthesizing R-CDs with tunable functional groups. In this study, p-phenylenediamine and hydroquinone were selected as precursors with specific hybridized carbon structures for synthesizing R-CDs with tunable functional groups by hydrothermal method. The proportion of precursors in the reaction system were adjusted to successfully synthesize R-CDs with various contents of oxygen and amino groups. Experimental results showed that the fluorescence of the R-CDs was effectively quenched by Fe3+ through the formation of R-CDs/Fe3+ complex. The fluorescence quenching ability of Fe3+ for R-CDs with different N/O ratios were also investigated. The fluorescence quenching efficiency of Fe3+ for R-CDs increased with the oxygen content of the R-CDs. By selecting R-CDs with oxygen-containing surface groups (R-O-CDs) as nanoprobe, an “on–off-on” fluorescent sensor has been developed for dual-detection of Fe3+ and pyrophosphate (PPi). A detection limit of 0.527 μM for Fe3+ and 0.24 μM for PPi were achieved. The as-developed R-O-CDs/Fe3+ nanoprobe was also successfully used to detect Fe3+ and PPi in real samples. Furthermore, an IMPLICATION logic gate was designed.

Naphthalene-grafted MOF as a unique fluorescent sensor for “turn-off” detection for Fe3+ and “turn-on” detection for ClO4- in different solvents with high selectivity and sensitivity

Naphthalene-grafted zirconium-organic framework UiO-66 (HNA@UiO-66-NH2) was synthesized via the Schiff base reaction. HNA@UiO-66-NH2 retained the original crystal structure of UiO-66 and high thermal stability. HNA@UiO-66-NH2 exhibited fluorescence sensing ability in two modes, “turn-off” response to Fe3+ in methanol and “turn-on” response to ClO4- in ethanol with high selectivity and sensitivity accompanied by obvious changes of fluorescence color. Its fluorescence intensity presented linear changes with the concentrations of Fe3+ and ClO4- with low detection limits (LOD) were 0.911 μM for Fe3+ and 1.44 μM for ClO4-. In addition, HNA@UiO-66-NH2 can simply identified Fe3+ and ClO4- in the test paper mode with naked eyes. The photoinduced electron transfer (PET) from excited HNA@UiO-66-NH2 to Fe3+ ion and the absorption competition quenching (ACQ) were responsible for the fluorescence quenching, the fluorescence enhancement of HNA@UiO-66-NH2 induced by ClO4- was attributed to the hydrogen bond formation between HNA@UiO-66-NH2 and ClO4-. The satisfying accuracy in detection of Fe3+ in serum and the good recovery of HNA@UiO-66-NH2 in detection of Fe3+ and ClO4- in water samples confirmed the practical application capability. This work paved a way to fabricate the fluorescent sensing materials for the simple, accurate and instantaneous detection and recognition of the different analytes.

CdII-based compound as a multi-responsive fluorescent probe for sensing FeIII cations and CrVI oxyanions.

A new luminescent CdII compound, poly[[μ2-1,4-bis(1H-imidazol-1-yl)benzene]{μ2-5-[(3-carboxylphenoxy)methyl]isophthalato}cadmium(II)], [Cd(C16H10O7)(C12H10N4)]n or [Cd(HL)(1,4-bib)]n {H3L is 5-[(3-carboxyphenoxy)methyl]isophthalic acid and 1,4-bib is 1,4-bis(1H-imidazol-1-yl)benzene}, I, has been synthesized successfully from CdII and a semirigid tricarboxylic ligand under hydrothermal conditions. Structure analysis shows that I is a two-dimensional structure with the point symbol {44.62}. The three-dimensional framework is constructed by O-H...O hydrogen bonds and π-π stacking interactions. Furthermore, the obtained CdII compound displays high solvent stability and excellent thermal stability, as shown by powder X-ray diffraction and thermogravimetry measurements. Studies of the luminescence properties reveal that compound I can act as a promising luminescent sensor for detecting FeIII cations and CrVI oxyanions with high selectivity and low detection limits (0.19 µM for Fe3+ and 1.13 µM for Cr2O72-), and is additionally free from the interference of other ions. The mechanism of selective quenching was studied by measuring the UV-Vis absorption of the host compound and the target analytes.

Quadruple analyte responsive platform: Point-of-care testing and multi-coding logic computation based on metal ions recognition and selective response

While it is recognized that instrumentation techniques can provide precise and sensitive solutions to heavy metal ion monitoring, it remains challenging to transform laboratory testing into a convenient, on-site, and quantitative sensing platform for point-of-care testing (POCT) in a resource-constrained setting. To address these limitations, an affordable and user-friendly colorimetric POCT sensing system is proposed here for selectively monitoring four metal ions (Fe3+, Co2+, Pb2+, and Cd2+) based on the sulfur quantum dots (S dots). Quadruple distinct visual signals (green, brown, precipitation, and bright yellow) are presented on the fabricated paper-based analytical devices (PADs) when mixing S dots and metal ions. The high-quality photographs of the PADs are captured by a scanner, while a smartphone App converts visual signals to HSV values. The quantitative analysis relies on the digital colorimetric reading, and the limits of detection are 0.59, 0.47, 0.82, and 0.53 μM for Fe3+, Co2+, Cd2+, and Pb2+, respectively. This metal ions-responsive platform is engineered as a smart strategy for multiple logic operations (YES, NOT, AND, INHIBIT, and NOR) by integrating multi-responsive blocks into the S dots with encoded patterns, which improves the computing capability. Accordingly, this strategy demonstrates its potential for on-site environmental testing and sophisticated molecular computation.

Propylimidazole Functionalized Coumarin Derivative as Dual Responsive Fluorescent Chemoprobe for Picric Acid and Fe3+ Recognition: DFT and Natural Spring Water Applications.

A propylimidazole functionalized coumarin derivative (IPC) was fabricated for the first time and applied as a dual responsive fluorescent chemoprobe for sensitive and selective recognition of picric acid (PA) and Fe3+. Strong fluorescence quenching phenomena of the IPC were observed in H2O/ACN (5/95, v/v) medium (λem=408 nm) upon the additions of Fe3+or PA. The fabricated dual responsive IPC offered good selectivity and sensitivity with the low limit of detection values (0.92 µM for PA and 0.22 µM for Fe3+) lower than the acceptable amounts of Fe3+ and PA by the international official authorities. The validation study for the chemoprobe IPC for PA and Fe3+ was also performed. The interaction phenomena of IPC with PA and Fe3+ based on the findings of a range of experiments were considered and DFT computations were done to verify their recognition mechanisms. The sensing phenomena of IPC towards PA (1:1) and Fe3+ (3:1) were confirmed by the MALDI TOF-MS, FT-IR, 1H-NMR titration and Job's methods. Furthermore, the compound IPC was effectively applied as a fluorescent sensor for Fe3+ and PA detection in real natural spring water samples.

A water-stable Zn(II) coordination polymer for a high sensitivity detection of Fe3+ and 2,4,6-trinitrophenol

A Zn(II) coordination polymer [Zn(L) (H2O)2]n (1, 1-Zn) (H2L ​= ​5-(pyrazin-2-yl)isophthalic acid) was synthesized through hydrothermal synthesis and systematically characterized. 1 is a three-dimensional (3D) framework with an uninodal 3-connected bto topology. Interesting, two helical chains and a zigzag chain are grouped together to form a 3D framework of 1. Moreover, 1 shows good chemical stability towards common organic solvents and high hydrothermal stability. The suspension of 1 shows good luminescence performance in water. Further luminescence experiments display that 1 shows high sensitivity and selectivity for sensing Fe3+ ion and TNP (2,4,6-trinitrophenol) in aqueous media. The highest quenching constants (Ksv) and the lower the limits of detection (LODs) are about 1.7 ​× ​104 ​M−1 and 0.44 ​μM for Fe3+, and 3.8 ​× ​104 ​M−1 and 0.19 ​μM for TNP, respectively. In addition, the possible luminescence sensing mechanisms were carefully investigated by PXRD, IR, XPS (X-ray photoelectron spectroscopy), and UV spectroscopy. The results demonstrate that 1 can be used as a bifunctional luminescent probe for sensing Fe3+ ion and TNP (2,4,6-trinitrophenol) in aqueous media.