Water Content In Organic Solvents Research Articles

Multiple stimulus responsive of a novel naphthalenediimide-based 2D alkaline-earth metal MOF material: Hydrochromism, amine-/acid-induced chromism and ionochromism as well as visual artificial film application

Metal–organic frameworks (MOFs) with naphthalene-1,4,5,8-tetracarboxylic dianhydride (H4NDISA) chromophoric unit provide an intriguing platform for the design of multiple stimulus responsive materials. Herein, the first NDISA-based 2D MOF [Ca(H2NDISA)(DMF)3]∙H2O (Ca-NDISA) constructed from alkaline-earth metal ion was successfully synthesized. The structural analysis shown that a binuclear secondary building unit (SBU) [Ca2(COO)2(DMF)6] is extended to generate a 2D planar network structure with abundant open-activity sites, endowing Ca-NDISA with multiple stimulus responsive chromic behaviors. Ca-NDISA could undergo a color change from yellow to red in hydrochromism, rendering it with the applications in detecting the water content of organic solvents, as a humidity sensor when fabricating a PMMA@Ca-NDISA film, and a potential hydrochromic imaging material. In amine-/acid-induced chromism, Ca-NDISA respectively changed its color to red and brown when exposed to strong acid and some small size ammonia/organic amines vapors environment, which makes the PMMA@Ca-NDISA film as a visual and portable recognition detector for acids and amines. In ionochromism, Ca-NDISA is suitable for the naked-eye discrimination and detection of I− with obvious color change to black brown. Our work not only provide a facile way to obtain NDISA-based 2D MOF with multi-stimulus responsive chromic properties, but also present some convenient chromism devices, which will enrich the family of multifunctional chromic materials for practical applications.

Visualized detection of water by modified metal organic framework-199 and its portable test paper with reversible color change

Herein, we fabricate a melamine modified metal organic framework-199 composite (MOF-199@melamine), of which the structure is affected by the dynamics of the guest H2O molecule with significant color change. It realizes the visualized quantitative detection of water in a variety of organic solvents within 30 s. Moreover, DMF restored the original structure by replacing H2O molecules, realizing the regeneration of the materials. On this basis, PTFE-MOF-199@melamine test paper is developed to portably detect water content in organic solvents (maximum 0 %-98 % (v/v) water content) and ambient relative humidity (11–85 %). The test paper can be recycled four times with a regeneration rate higher than 90 %. The results are expected to solve the problems of existed electrochemical or fluorescence strategy such as the complicated operation process and signal output/reading system.

Electrochemical Detection of Single Aqueous Droplets in Organic Solvents via Pitting Collisions.

We report a novel detection method for single aqueous droplets in organic solvents by the collisional contact of the droplet, inducing the partial deformation of the ultramicroelectrode (UME) surface. For various chemical reactions in organic solvents, water impurities affect the catalytic activity, leading to a loss of productivity and selectivity. Therefore, it is necessary to monitor the water content of organic solvents in real time between many chemical production processes, from the laboratory to the industrial scale. Our method enables the detection of water contamination by real-time monitoring of the electrochemical signals or observing morphological changes in the microelectrode. When an aqueous droplet collides with the UME, the contact area of the electrode is electrolyzed, forming pits on the surface where the droplet falls. Current transient analysis shows a unique current spike corresponding to the reaction inside the adsorbed single aqueous droplet, which differs from those detected by the faradaic/nonfaradaic reaction of collision of other particles. Moreover, this analytical method can record the history of collision events from pits on the UME surface, implying that inspecting the UME surface could be a quick screening method for solvent contamination. Based on a comparison of the electrochemical signals and morphological changes of the electrode after each event, the sizes of the pits and droplets are related. A COMSOL simulation is performed to explain the shape of the peak current and pit formation during collision events. This experimental concept elucidates the dynamic behavior of aqueous droplets on a positively biased metal electrode.

Porphyrin based covalent organic polymer for the fluorescence sensing of water in organic solvents

One porphyrin covalent organic polymer (PorMeO-COP) via Schiff base condensation using 5,10,15-tris(4-aminophenyl)porphyrin and 2,5-dimethoxyterephthaladehyde as the monomers have been designed and synthesized for fluorescence sensing of water content in organic solvents. The resulting PorMeO-COP display significant fluorescence enhancing upon the addition of different amount of water in eight common hydrophilic solvents. The sensing ranges are achieved over 0.2–6%, 1–20 %, 0.2–15 %, 1–16 %、1–40 %、2–10 %、4–14 % and 0.2–25 % (v/v) for water in methanol, ethanol, acetonitrile, acetone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide and 1,4-dioxane, respectively, and the limit of detection (LOD) are 0.032 %, 0.076 %, 0.054 %, 0.007 %, 0.014 %, 0.037 % and 0.024 % (v/v), respectively. These findings reveal PorMeO-COP can serve as fluorescence sensor to detect water content in organic solvents.

A highly water-soluble hydrogen-bond-induced emission carbon dots for ratiometric fluorescent detection of water content in organic solvents

Water in organic solvents is a prevalent impurity that significantly influences chemical reactions and industrial processes. Carbon dots (CDs) gained attention as promising tools for chemosensing due to their advantageous characteristics, including easy synthesis, cost-effectiveness, and excellent adjustability and stability. However, limited solubility in water and turn off fluorescence response mode hinder the practical utilization of CDs for water sensing. To tackle such dilemma, a highly water-soluble CDs with distinctive hydrogen-bond-induced emission (HBIE) was rationally designed through introducing sulfone group into the widely employed p-phenylenediamine precursor. The inclusion of sulfone group imparts the CDs with notable water solubility, as well as distinctive ratiometric fluorescent response towards water content, exhibiting high sensitivity and selectivity. Upon exposure to water, the emission color of CDs undergoes a real-time transition from blue to yellow-green, which can be readily discerned by naked eyes. The CDs have been successfully applied in detecting water in commercially available alcohol. This study presents a straightforward yet efficacious approach for rationally design of CDs with unique HBIE characteristics and ratiometric fluorescent response, offering great potential for practical chemosensing applications.

Visual detection of water content in liquor with near-infrared fluorescence sensor assisted by smartphone

Water content was an essential indicator in organic solvents, and it was necessary to develop a facile, cheap and readily available tool for the real-time, specifical and sensitive detection of water content. In this work, two novel D-π-A type near-infrared fluorescence sensors (DCM-1 and DCM-2) were designed and synthesized for the detection of trace water in organic solvents. DCM-1 and DCM-2 with solvent-dependent effects and large Stokes shift (>120 nm) showed good linear “intensity-to-content” relationships in four commonly-used organic solvents, and accomplished the ultra-fast and high-accuracy detection of the trace water in organic solvents. More importantly, a portable, fast, and accurate smartphone-assisted visual assay was designed for visual quantitative detection of the water content in organic solvents with a detection limit as low as 1.028 % v/v (e.g. in ethanol) and a wide detection range (0–60 % v/v). The smartphone-based visual assay was further applied to estimate the water content in disinfection alcohol and commercial liquor, which furnished a new strategy and broad prospects to achieve the accurate onsite detection of water content.

Determination of Trace Water Using Fluorescence Probes Based on Nitrogen‐Doped Carbon Quantum Dot Fluorescence Senors (Y‐CDs and R‐CDs)

AbstractIn this work, we reported two nitrogen doped carbon quantum dot fluorescence sensors (Y‐CDs and R‐CDs) with good stability and luminescence efficiency, which can be quickly, sensitively and low‐cost for the determination of trace water content in organic solvents. Using o‐phenylenediamine and p‐phenylenediamine as nitrogen sources and terephthalic acid as carbon sources, the preparation was carried out through simple solvothermal synthesis and heteroatom doping. The luminescence characteristics and interaction mechanism with the target were discussed. The results indicate that the two carbon dots can effectively quench the water content in acetone, ethanol, and DMF, as well as physical interactions such as hydrogen bonding and dynamic quenching, which are the reasons for the observed quenching effect. Based on this, a new method for determining water content in organic solvents using carbon quantum dot fluorescence probes has been established. The linear relationship between the fluorescence quenching efficiency F0/F of two carbon quantum dots and the water content in different organic solvents was studied. The detection limits (LOD) of water in acetone, ethanol and N,N‐dimethylformamide (DMF) were 0.17 %, 2.35 %, 0.26 %, respectively, determined by Y‐CDs. The LOQ of acetone, ethanol, and DMF were 0.554 %, 7.83 %, 0.855 %, respectively. The LOD of water in acetone, ethanol and DMF determined by R‐CDs were 0.056 %, 0.69 %, 0.27 % and the LOQ was 0.187 %, 2.290 %, 0.909 %, respectively. Good recovery rates and precision were achieved in practical applications.

A dual-function fluorescence 'turn-on' probe that allows Zn (II) bioimaging and quantification of water in the organic solvent.

Herein, a Eugenol-derived fluorescence 'turn-on' probe FLHE was synthesized by condensing 2-((3-(trifluoromethyl)phenyl)amino)benzohydrazide with 5-allyl-2-hydroxy-3-methoxybenzaldehyde. FLHE demonstrated very low fluorescence in the studied organic solvents of varying polarities. However, upon titration with Zn2+ in HEPES buffer (pH=7.4, 50% ACN, v/v), FLHE showed 40-fold higher fluorescence signals indicating the formation of the FLHE-Zn2+ complex. The fluorescence turn-on phenomenon upon FLHE-Zn2+ complex formation results from a chelation-enhanced fluorescence (CHEF) effect. The FLHE-Zn2+ complexation demonstrated a stokes shift of 156nm (λex=350nm, λem=506nm) and an about 33-fold increase in the quantum yield (FLHE, Φ=0.007; FLHE-Zn2+ complex, Φ=0.23). The binding constant (Ka) determined by the Benesi-Hildebrand plot for interaction between FLHE and Zn2+ was 5.33×103 M-1. FLHE demonstrated a LOD of 31.8nM for detecting Zn2+ in the environmental samples without interference from other cations and anions. FLHE-based paper strip (FLHE-PS) assay was developed to quantify the Zn2+ ions in water and the water content of organic solvent. FLHE-PS allows the detection of Zn2+ in aqueous solutions with a LOD of 63.2nM and quantifying water in acetonitrile with a LOD of 0.14%. These results indicate that the FLHE has high applicability for detecting Zn2+ in living cells and environmental samples and detecting the presence of water in the organic solvents.

Study on the modulating effect of halogen atom substitution on the detection range of water content detection probes in organic solvents

Fluorescence probes based on the variations of aggregation state (Aggregation-Induced Emission (AIE) and Aggregation-Caused Quenching (ACQ)) have received widespread attention due to their simplicity, efficiency and intuitiveness. However, typical probes are highly sensitive to changes in polarity and slight variations in the external environment can cause a complete change in the aggregation state. With the aim of expanding the detection range of the molecular probe, this work adopts a different design strategy from adjusting the molecular backbone but regulates the fluorescence behavior of the Schiff base molecular backbone by introducing different halogen atoms. Systematic studies show that when chlorine serves as substitutional atoms (3,5-Cl Salen), the probe can achieve full-range detection of water content (0–100 vol%) in ethanol and DMF. To our knowledge, the 3,5-Cl Salen represents the best water content probe in organic molecules. Experimental and theoretical studies have shown that the adjustment of halogen atoms can linearly change the charge distribution on the benzene ring and precisely control the strength of intermolecular interactions. At the same time, we developed a fluorescent filter paper based on 3,5-Cl Salen and used smartphones for rapid, sensitive and precise on-site measurement of water content in organic solvents.

Design of polarity-dependence orange emission multifunctional carbon dots for water detection and anti-counterfeiting

In this work, polarity-dependence orange emission multifunctional carbon dots (o-CDs) were designed for water detection in organic solvents and anti-counterfeiting. The o-CDs were readily fabricated by a one-step hydrothermal method with citric acid and p-aminoazobenzene as precursors. The o-CDs possess bright orange fluorescence, good photochemical stability, and polarity-dependence characteristic. With the increase of polarity, the emission peak of o-CDs gradually red-shifted. Meanwhile, with the increase of water content in organic solvent, the fluorescence intensity of o-CDs decreased significantly and the emission peak position gradually red-shifted. This is due to the specific water-fluorophore interaction (particularly hydrogen bond effects), part of o-CDs gathered, making the carbonized cores suffer from π–π stacking and reduced the transition energy gap. Based on this, a fluorescence sensing platform with satisfactory recoveries and relative standard deviation was constructed to detect water content in real alcohol solvents. Furthermore, the o-CDs were further designed into fluorescent ink and prepared fluorescent flexible films, realizing information encryption and solid-state fluorescence. This work opens up a possibility for the development of polarity-dependence orange emission nanomaterial based on CDs for water detection, anti-counterfeiting, and solid-state fluorescence.

Paper-based sensor based on lead-free manganese halide for the determination of water content in organic solvents.

A highly stable and luminescent lead-free manganese(II) halide hybrid MnBr4(TMN)2 (C34H42Br4MnN4) was designed and synthesized by introducing a large cationic organic spacer. The MnBr4(TMN)2 displays high luminescence with quantum yields up to 77% and possesses turn-off fluorescence behavior (Ex/Em=365/546 nm) for water. These properties make the MnBr4(TMN)2 a promising candidate as an alternative indicator for the detection of water with potential applications for the fabrication of LEDs. Herein, a paper-based sensor based on MnBr4(TMN)2 is described for the determination of water content in organic solvents. The mechanism of water sensing can be tentatively explained by fluorescence quenching originating from the destruction of water dueto the Mn-Br bonds of MnBr4(TMN)2. The MnBr4(TMN)2-based paper sensor exhibits an excellent discrimination ability of water content in therange 0-25.0% with a detection limit of 0.27%. Satisfactory recoveries (94.91±4.09% to 103.23±2.38%) are obtained in spiked ethanol solvent samples, which demonstrate that the MnBr4(TMN)2-based paper sensor is capable of detecting water content in real ethanol solvent samples.

A novel styrylpyridine derivatives: Supramolecular assembly with cucurbit[8]uril for detection of difenzoquat, white light material and beyond

In this work, we developed a novel fluorescent molecule (SPy) that can form a supramolecular fluorescence probe with cucurbit[8]uril (Q[8]) (Q[8]@SPy) and exhibit a unique response to the herbicide difenzoquat in aqueous solution. Moreover, excellent optical properties in different solvents were shown by the fluorescence spectra of SPy. It was further shown that SPy could not only detect the water content in organic solvents, but also exhibit potential applications in the field of white-light emission materials and anti-counterfeiting.

Design of a Synthetic Strategy to Achieve Enhanced Fluorescent Carbon Dots with Sulfur and Nitrogen Codoping and Its Multifunctional Applications.

Here, a rational strategy to achieve multifunctional N, S codoped carbon dots (N, S-CDs) is reported, aiming to improve the photoluminescence quantum yields (PLQYs) of the CDs. The synthesized N, S-CDs have excellent stability and emission properties independent of excitation wavelength. Through the introduction of S element doping, the fluorescence emission of CDs is red-shifted from 430to 545nm, and the corresponding PLQYs can be greatly enhanced from 11.2% to 65.1%. It is found that the doping of S elements causes an increase in the size of CDs and an elevated graphite N content, which may be the key factors to cause the redshift of fluorescence emission. Furthermore, the introduction of S element also serves to suppress the nonradiative transitions, which may be responsible for the elevated PLQYs. Besides, the synthesized N, S-CDs have certain solvent effect and can be applied to detect water content in organic solvents, and have strong sensitivity to alkaline environment. More importantly, the N, S-CDs can be used to achieve an "on-off-on" dual detection mode between Zr4+ and NO2 - . In addition, N, S-CDs combinedwith polyvinylpyrrolidone (PVP) can also be utilized as fluorescent inks for anti-counterfeiting applications.

A highly sensitively “off–on-off” fluorescence probe for detection of aluminum ion and water as well as application in Chinese Baijiu

Developing highly sensitive fluorescent probe for Al3+ and H2O detection is highly desirable, due to aluminum toxicity poses a significant threat to public health. On the other hand, the determination of water content holds immense significance in a wide range of fields such as food processing, pharmaceutical manufacturing. In this paper, a novel acylhydrazone-based fluorescent probe P was successfully synthesized and characterized for the sequential detection of Al3+ and water in alcohols. The probe P exhibited a remarkable “turn-on” response towards Al3+ by emitting yellow fluorescence at 567 nm, with high selectivity and large Stokes shift (147 nm). Meanwhile, the in situ formed P-Al3+ complex demonstrated significant solvatofluorochromic characteristic, which could be utilized as a second probe for detecting water via fluorescence quenching with low detection limit in alcohols (0.008%, methanol; 0.013%, ethanol; 0.013%, isopropanol; 0.037%, n-butanol; vol.%) and acetonitrile (0.072%, vol.%). Moreover, the P-Al3+ complex was able to detect the alcoholic strength of Chinese Baijiu without the interference of other alcohols, providing an excellent recovery rate (100.0–107.0%). Different Chinese Baijius, with various alcoholic strength, could be distinguished by simple test strips. Furthermore, the P-Al3+ complex could also analyze the water content in organic solvents.

Dual-Emissive Carbon Dots: Exploring Their Fluorescence Properties for Sensitive Turn-Off-On Recognition of Ferric and Pyrophosphate Ions and Its Application in Fluorometric Detection of the Loop-Mediated Isothermal Amplification Reaction.

In this study, dual-emissive carbon dots (CDs) were prepared using p-phenylenediamine (pPDA) and phytic acid (PA) precursors via a one-pot-hydrothermal method. The photophysical, morphological, and structural characterization of CDs was carried out using absorption, fluorescence, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and high-resolution transmission electron microscopy (HR-TEM) analysis. The as-prepared CDs displayed dual-fluorescence peaks at 525 and 620 nm upon excitation at 450 nm. The CDs showed good photostability and exhibited solvent-dependent fluorescence properties. The solvatochromic behavior of CDs was utilized to detect water content in organic solvents. Furthermore, the dual-emissive property of CDs was utilized for the sequential detection of ferric (Fe3+) and pyrophosphate ions (PPi) by a fluorescence turn-off-on mechanism. The proposed assay showed appreciable fluorescence response toward Fe3+ and PPi with high selectivity and good tolerance for common interfering ions. The potential practical application of the CD probe was ascertained by carrying out the fluorometric detection of PPi to affirm the loop-mediated isothermal amplification (LAMP) reaction specific for Mycobacterium tuberculosis (negative and positive clinical samples).

Solvatochromism as a tool to visually recognise wide range of commonly used solvents and inexpensive dye based optical sensor for H2O, D2O and H2O2

An inexpensive bisphenol based optical sensor (BP) obtained from single step reaction of 4-hydroxybenzyladehyde and 2,6-dimethyl phenol was designed and subsequently synthesized. BP effectively recognize wide range of commonly used solvents through solvatochromism. The recognition technique of the solvents was also extended to computer application detection. Induced deprotonation enhanced the activity of sensor enabling detection of water and heavy water content in organic solvents up to 1.57 × 10-8 M and 2.64 × 10-8 M respectively as well as qualitatively distinguishing water from its heavy form. The BP effectively detect H2O2 colorometrically with LOD of 1.86 × 10-6 M and the efficiency of H2O2 detection was significantly improved through induced deprotonation of BP. Colorimetric and flurometric H2O2 detection of deprotonated form of BP (DBP) were also demonstrated. BP as well as DBP selectively detect H2O2 over other peroxides namely benzoyl peroxide and tert-butyl hydro peroxide. Then, BP was effectively immobilized in hydrogel matrix for solid state detection of H2O2 in purely aqueous system through induced deprotonation of immobilized BP with base namely F-/CN– ion. The hydrogel composite film exhibit significant stability to various environmental conditions.

Combined experimental and TD-DFT study of a highly sensitive AIE-based probe for the detection of water in organic solvents and its application in inkless writing

The present manuscript highlights a newly synthesized pyrene-based probe (PyQ), which has a high affinity for the detection of water in water-miscible organic solvents. The efficient probe followed the principle based on aggregation-induced emission and showed its potential behavior as a sensor by detecting water in common water-miscible organic solvents by the fluorometric method. The chemosensor PyQ has identified water separately from many other solvents as its emission maxima in presence of water is found near 510 nm while for others it is around 410 – 440 nm. Moreover, in different water-miscible solvents by increasing the percentage of water, fluorescence studies have been carried out and were found that increasing water content in organic solvents increased the fluorescence intensity of the PyQ as well as provided a redshift to the emission intensities. Furthermore, the response of PyQ towards pH and the LOD and LOQ of PyQ towards a low level of water content in different organic solvents were determined. TD-DFT studies were carried out in the aqueous phase to clarify the optical and electronic properties of the probe. The moisture detection capacity of PyQ in presence of silica gel desiccant was also showcased. Finally, the utilization of PyQ in inkless writing and in reusable or rewritable paper strips disclosed its potential for real-life applications, which strengthened its use as a water sensor.

Fluorescent material based on Al-MOF and phenazine groups for detection of water content in organic solvents

[Formula: see text]-MIL-101(Al) material containing phenazine groups, i.e. 1-metal-organic framework (MOF) has been prepared and characterized via FT-IR, PXRD, TGA, SEM and [Formula: see text] adsorption and desorption isotherm in this work. 1-MOF can exhibit emission peaks at 447 nm (in pure aqueous solvent) and 595 nm (in pure organic solvents) under 327 nm ultraviolet excitation, respectively. Based on this interesting feature, 1-MOF has been effectively used as a ratiometric fluorescent probe to detect water content in organic solvents. The luminescence color of 1-MOF changed obviously from red to blue with the increasing of water content in organic solvents, which can be observed by the naked eyes. The route to detect water content in organic solvents is fast, accurate and possessing great application potential.

Nanoscale carbon dot-embedded metal-organic framework for turn-on fluorescence detection of water in organic solvents.

An easy-to-use, highly selective, and real-time organic solvent quality assessment is desirable to detect water contamination in organic solvents. Herein, a one-step procedure using ultrasound irradiation was used for encapsulating nanoscale carbon dots (CDs) into metal-organic framework-199 (HKUST-1) to form CDs@HKUST-1 composite. The CDs@HKUST-1 exhibited very weak fluorescence due to photo-induced electron transfer (PET) from the CDs to the Cu2+ centers, acting as a fluorescent sensor in its off-state. The designed material can detect and discriminate water from other organic solvents, driven by turn-on fluorescence. This highly sensitive sensing platform could be applied for the detection of water in ethanol, acetonitrile, and acetone with wide linear detection ranges of 0-70% v/v, 2-12% v/v, and 10-50% v/v and limits of detection of 0.70% v/v, 0.59% v/v, and 1.08% v/v, respectively. The detection mechanism is attributed to the interruption of the PET process due to the release of fluorescent CDs after treatment with water. A smartphone-based quantitative test was successfully developed to monitor the water content in organic solvents utilizing CDs@HKUST-1 and a phone color processing application, thus making it possible to develop an on-site, real time and easy-to-use sensor for water detection.

Detection of Water Content in Organic Solvents Using Green Fluorescent Carbon Dots

Detection of Water Content in Organic Solvents Using Green Fluorescent Carbon Dots