An ion synergism fluorescence probe via Cu2+ triggered competition interaction to detect glyphosate.

The widespread use of glyphosate (Gly) poses significant risks to environmental and human health, underscoring the urgent need for its sensitive and rapid detection. In this work, we innovated by developing a novel material, ionic liquids, which formed the ionic probe "[P66614]2[2,3-DHN]-Cu2+ (PDHN-Cu2+)" through coordination with Cu2+. This probe capitalized on the distinctive fluorescence quenching properties of ionic liquids in the presence of Cu2+, driven by synergistic interactions between anions and cations. Glyphosate disrupted the PDHN-Cu2+ coordination structure due to its stronger affinity for Cu2+, triggering a "turn-on" fluorescence response. Impressively, PDHN-Cu2+ enabled the sensitive detection of glyphosate within just one minute, achieving a detection limit as low as 71.4 nM and excellent recovery rates of 97-103% in diverse samples. This groundbreaking approach, utilizing ionic probes, lays a robust foundation for the accurate and real-time monitoring of pesticides, employing a strategy based on synergism and competitive coordination.

A fluorescence ionic probe utilizing Cu2+ assisted competition for detecting glyphosate abused in green tea.

Food fraud caused by the violation of glyphosate use in tea is frequently exposed, posing a potential health risk to consumers and undermining trust in food safety. In the work, an ionic fluorescent probe "[P66614] [4HQCA]-Cu2+ (PHQCA-Cu2+)" was constructed using Cu2+ and ionic liquids coordination through a competitive coordination strategy to detect glyphosate. This probe exhibited a prominent "turn-on" fluorescence response in glyphosate detection. PHQCA-Cu2+was destroyed by glyphosate with its strong coordination capability, and a new complex re-formed simultaneously between glyphosate and the Cu2+ in it, where Cu2+ served as an "invisible indicator" influencing fluorescence changes. Remarkably, PHQCA-Cu2+formed rapidly within 5 s, demonstrated exceptional sensitivity and selectivity, and satisfactory detection performance on paper strips impregnated withPHQCA-Cu2+.Importantly,PHQCA-Cu2+showed excellent recoveries in various green tea, which offered a viable method for identifying contaminated products from the supply chain quickly to enhance overall food safety surveillance.

Real-time monitoring of mercury(II) in water and food samples using a quinoline-based ionic probe.

Herein, a novel ionic fluorescent probe for mercury(II) detection is presented consisting of a functional quinoline-based IL. Interestingly, the probe displayed high sensitivity (0.8 nM) and selectivity through the regulation function of electrostatic attraction, where its performance was significantly superior to that of quinoline probes without negative charge. Furthermore, the probe was found to exhibit two different fluorescent signals and colorimetric signals in the presence of different concentrations of mercury(II), which was consistent with the reaction mechanisms of the generation of large conjugated systems and the formation of anion-mercury(II) complexes. Moreover, this probe could be further loaded on a simple filter paper to serve as a visual paper sensor due to its adequate response time of less than 5 s. This regulation function strategy of electrostatic attraction has excellent potential for use in the precise detection of targeted analytes in real complex samples with improved accuracy and selectivity.

Highly sensitive visual fluorescence sensor for aminoglycoside antibiotics in food samples based on mercaptosuccinic acid-CdTe quantum dots.

The inappropriate application of aminoglycoside antibiotics (AGs) in food products has led to the accumulation of AG residues in the human body. In this study, a novel fluorescent sensor based on mercaptosuccinic acid (MSA)-modified CdTe quantum dots (QDs) were designed for the rapid visual detection of a representative AG, neomycin (NEO). The proposed sensor showed excellent performance toward NEO determination, with a detection limit of 1.60 × 10-8 mol/L. Furthermore, MSA-CdTe QDs can be applied to the visual detection of NEO, where the fluorescence changes from bright yellow to dark red with increasing NEO concentration. Most importantly, high selectivity of MSA-CdTe QDs toward NEO was achieved even in the presence of other antibiotics, which are common interfering agents, with a recovery rate in actual samples as high as 95.66 %-100.77 % and an RSD of less than 3.15 %.

Fluorescent and Colorimetric Ionic Probe Based on Fluorescein for the Rapid and On-Site Detection of Paraquat in Vegetables and the Environment.

Detection of pesticide paraquat (PQ) is of considerable significance to ensure food safety, and its rapid and on-site detection is still a challenge. Aimed at the ion characteristics of PQ, an "enrichment and detection" strategy was proposed to improve the sensitivity through electrostatic attractions, and the ion characteristic of probes was adopted to increase the portability through avoiding aggregation-caused quenching effects in the paper strips. Herein, a novel anion-functionalized ionic liquid (IL) probe with a large conjugated plane and rich π-electrons ([Fluo][P66614]2) was designed as a fluorescent and colorimetric dual-channel probe to sensitively and rapidly detect trace amounts of PQ in vegetables and the environment. The proposed probe exhibited good linearity with a detection limit of 64.0 nM in the PQ concentration range of 0.3-7.0 µM (fluorometry) and 0.1 µM in that of 0.1-8.0 µM (colorimetry), respectively. In addition, it displayed a rapid fluorescence quenching response from green to dark (<5 s) and excellent anti-interference (among 23 other pesticides) due to dual effects of electrostatic attraction and π-π stacking. Most importantly, the lipophilic IL probe could be applied in real vegetables and environmental samples with a satisfying recovery rate of 98-103% and assembled into a handy paper strip that achieved the visual semiquantitative detection of PQ. This ionic probe provides a feasible approach for rapidly and conveniently detecting PQ for ensuring agricultural and food safety and opens a new avenue to detect ion-responsive analytes in real complex samples by an "enrichment and detection" strategy.

A fluorescent and colorimetric sensor based on ionic liquids for the on-site monitoring trace gaseous SO2.

SO2 could cause severe environmental pollution and health threat, so real-time and on-site monitoring of SO2 has attracted considerable attention. This work proposed a novel ionic liquid-based sensor, called trihexyl (tetradecyl) phosphonium fluorescein ionic liquid, which can accurately detect SO2 with its fluorescent and colorimetric dual-readout assay without seventeen gases interference (eg: NO, N2, CO2, O2, COS, HCl, CHCl3). GC-MS was also used to verify the validation of the detection method. First, this fluorescein-based IL sensor exhibited fluorescence green and colorimetric yellow signals. When the sensor was exposed to gaseous SO2, the green fluorescence quenched, and the colorimetric yellow color faded due to chemical bond interaction. Also, the proposed IL sensor exhibited good linearity in the SO2 concentration range of 5.0-95.0 ppm with a detection limit of 0.9 ppm (fluorescence) and 1.9 ppm (colorimetry), and recoveries of 97%∼103% with RSD less than 1.21%. Besides, the IL sensor could be easily assembled into a paper device by simple immersion, and the paper strip was exploited to realize a semiquantitative visual detection of SO2. These results indicated that the proposed fluorescence-colorimetric dual-signal chemosensor could be used as intelligent paper labels for real-time and on-site monitoring of SO2 in ambient air.

Dual channel sensor array based on ZnCdSe QDs - KMnO4: An effective tool for analysis of catechins and green teas.

A novel dual-channel sensor array based on the "off" and "off-on" phenomenon of ZnCdSe quantum dots (QDs) - KMnO4 system was established for the effective distinguish of 30 green teas with various species, grades and origins. Starting from optimization of QDs for the construction of the sensing system, their sensitivity and selectivity performances towards 10 representative green teas were tested first and the sensor systems based on ZnCdSe QDs were finally established. An obvious "off" response brought by the interactions between amino acids, quercetin, et al. and ZnCdSe QDs was obtained while an "off-on" phenomenon brought by the interactions between catechins and the ZnCdSe-KMnO4 system had also been verified. Furthermore, based on the differential fluorescence "off-on" response of seven catechins, the qualitative and quantitative analyses of these catechins were successfully carried out with the linear range from 0.5 to 10 µg/mL. Most importantly, through adopting the dual-channel sensor, 30 green teas with different species, origins and grades can be accurately identified with the LDA model according to the spectral signals and the recognition accuracy could achieve 100 %.

A succinct strategy for construction of nanoporous ionic organic networks from a pyrylium intermediate.

Hydroxyl group and pyridinium salt-bifunctionalized nanoporous ionic organic networks prepared via a simple two-step strategy under metal- and template-free conditions are presented. The structural features of the resultant polymer (e.g. high surface area, abundant hydroxyl groups and ionic functionalities) made it a promising candidate as an efficient scavenger of toxic oxo-anions from water.

Designing an anion-functionalized fluorescent ionic liquid as an efficient and reversible turn-off sensor for detecting SO2.

A novel anion-functionalized fluorescent ionic liquid was designed and prepared, which was capable of capturing sulphur dioxide with high capacity and could also be used as a good colorimetric and fluorescent SO2 sensor. Compared to conventional fluorescent sensors, this fluorescent ionic liquid did not undergo aggregation-caused quenching or aggregation-induced emission, and the fluorescence was quenched when exposed to SO2, and the fluorescence would quench when exposed to SO2. The experimental absorption, spectroscopic investigation, and quantum chemical calculations indicated that the quenching of the fluorescence originated from SO2 physical absorption, not chemical absorption. Furthermore, this fluorescent ionic liquid exhibited high selectivity, good quantification, and excellent reversibility for SO2 detection, and showed potential for an excellent liquid sensor.

Ionicity of Protic Ionic Liquid: Quantitative Measurement by Spectroscopic Methods.

The ionicity value, which is a key property of protic ionic liquids, was obtained by attenuated total reflection Fourier transform infrared spectroscopy and nuclear magnetic resonance, respectively, for a protic ionic liquid: n-propylammonium acetate. The method of potentiometric titration is found to not be suitable for such a kind of ionic liquid, as the ΔpKa of the compositing acid and base is relatively small. In the IR spectrum, molecular species can be directly observed in the range 1200-1800 cm-1, and the ratio of ionic and molecular species can be quantitatively calculated by the area of characteristic absorption peaks calibrated by a standard curve from NaAc/HAc solutions. The results show that 93% components in n-propylammonium acetate are ionic species. The NMR method was also introduced to test and verify the result. Despite that only one mixed peak can be observed for molecular and ionic species, the observed 1H chemical shift can be assumed to be the weighted average of them. In this way, the ionicity can be calculated and it fits well with the IR approach. It indicates that, for a protic ionic liquid with a relatively small ΔpKa value, spectroscopic methods such as IR and NMR could be applied to determine the ionicity.

Reversible CO2 Capture by Conjugated Ionic Liquids through Dynamic Covalent Carbon-Oxygen Bonds.

The strong chemisorption of CO2 is always accompanied by a high absorption enthalpy, and traditional methods to reduce the absorption enthalpy lead to decreased CO2 capacities. Through the introduction of a large π-conjugated structure into the anion, a dual-tuning approach for the improvement of CO2 capture by anion-functionalized ionic liquids (ILs) resulted in a high capacity of up to 0.96 molCO2 mol-1IL and excellent reversibility. The increased capacity and improved desorption were supported by quantum chemical calculations, spectroscopic investigations, and thermogravimetric analysis. The increased capacity may be a result of the strengthened dynamic covalent bonds in these π-electron-conjugated structures through anion aggregation upon the uptake of CO2 , and the improved desorption originates from the charge dispersion of interaction sites through the large π-electron delocalization. These results provide important insights into effective strategies for CO2 capture.