Water Content Of Solvent Research Articles

碳纳米点荧光探针对有机溶剂中水含量的检测

碳纳米点荧光探针对有机溶剂中水含量的检测

Photoinduced excited-state hydrogen bonding strengthening of hemiindigo for the drastically fluorescence quenching in protic solvent and water sensing in aprotic solvent

Hydrogen bonding in excited state could regulate the photochemical and photophysical processes of organic molecules. In this work, the fluorescence and photoisomerization properties of Hemiindigo (HI) in dioxane and methanol have been studied. Its fluorescence is bright in dioxane but faint in methanol and the photoisomerization in methanol is distinctly inefficient when compared with that in dioxane. By using time-resolved spectroscopy technology and quantum chemical calculation, hydrogen bonding strengthening between solutes and solvents in excited state, which induces enormously enhanced efficiency of internal conversion of HI in excited state, is assigned to the reason of significant fluorescence quenching and inefficient photoisomerization of HI in methanol. Because of the drastically fluorescence quenching effect of HI, trace water sensing with a limit of detection of 10 ppm in dioxane suggests the potential of HI as a fluorescence probe to quantitate the water content in aprotic organic solvents.

Two 8-hydroxyquinoline-based fluorescent chemosensors for ultra-fast and sensitive detection of water content in strong polar organic solvents with large Stokes shifts.

It is of great significance to detect the moisture in organic solvents before used in water-sensitive reactions. Herein, two Schiff base quinoline derivatives, 8-hydroxyquinoline-2-carboxaldehyde thiosemicarbazone (HQCT) and 8-hydroxyquinoline-2-carboxaldehyde (pyridine-2-carbonyl)-hydrazine (HQPH), were designed and synthesized by a simple one-step reaction, and used as fluorescent chemosensors for ultra-fast and sensitive detection of water content in strong polar organic solvents. Based on excited-state intramolecular proton transfer (ESIPT) process, HQCT and HQPH exhibited strong fluorescence emissions with large Stokes shifts in dimethyl sulfoxide (DMSO) and N, N-dimethylformamide (DMF) solvents compared to other various organic solvents, and their fluorescence quenching and fluorescent color changes were obviously observed with increasing water content. The experimental results revealed that the hydroxyl groups substituted at the 8-position of HQCT and HQPH played a key role in the fluorescence emission processes. Dynamic light scattering (DLS) and 1H NMR titration indicated that the sensing mechanism for the detection of water was based on inhibition of the ESIPT by H2O via forming hydrogen bonds. In the range of 0.0-1.8wt%, the fluorescence intensity of chemosensors changed as a linear function of water content. The detection limits of water in DMSO by HQCT and HQPH were as low as 0.0220wt% and 0.0274wt%, respectively. Moreover, HQCT and HQPH are successfully applied for the detection of moisture content in real commercial organic solvents.

One-step synthesis of hollow PEI-NaBiF4:Yb3+/Er3+ upconversion nanoparticles for water-responsive luminescent probe

Novel PEI-modified NaBiF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs) with hollow structure were prepared by a surface modification free one-step solvothermal method and applied as a luminescent probe to determinate water content in organic solvents. XRD, SEM and HRTEM results demonstrate that the obtained PEI-NaBiF4:Yb3+/Er3+ UCNPs are pure hexagonal phase with uniform size. The successful modification of PEI on the UCNPs surface was evidenced by ζ-potential test, XPS and TG analysis. These synthesized UCNPs are disintegrated into smaller nanoparticles in the presence of water and thus result in a surface quenching effect, which show the features of 0–100% wide range water response in various organic solvents. The sensing performance towards real samples was validated by the water content determination in beer, rum and white spirit. Furthermore, the luminescence intensity variation of the PEI-modified NaBiF4:Yb3+/Er3+ enable the test visualization and ease of portability.

Solvent Effect on Structure, Morphology and Catalytic Activity on Ammonium Perchlorate of Nano-MgWO4

For exploring the interesting solvent effect on structure and morphology, a variety of MgWO4 nanoparticles were prepared by a one-pot solvothermal method with different proportional solvents of water and ethylene glycol. The results showed that monoclinic wolframite crystalline structure of MgWO4 was successfully synthesized, corresponding to two standard cards of MgWO4 (JCPDS No. 27-0789) and MgWO4 (JCPDS No. 19-0776), respectively. The morphology of MgWO4 nanoparticles presents eight different shapes and orderly transforms from one shape to another with increasing water content in mixed EG-water solvents, and a possible mechanism was proposed. The catalytic activities of these MgWO4 nanoparticles on the thermal decomposition of Ammonium Perchlorate (AP) were compared using differential scanning calorimetry (DSC) method, and found to present good change rule with particle size.

Luminescent Lanthanide-Based Sensor for H2O Detection in Aprotic Solvents and D2O

Applied methods for detecting water impurities in organic solvents, such as Fischer titration, include wayward equipment and toxic reagents. This method is inapplicable for detecting H2O in D2O, but suitable techniques like NMR-, IR-, and mass-spectrometry are costly. We report a low-cost, novel luminescent sensor material based on terbium-europium 3D MOF compound developed for facile, portable, and disposable monitoring of water quantities. Our sensor is able to determine water traces in D2O and aprotic organic solvents. Treating the material to solvent leads to the change in intensities ratio of terbium and europium bands in emission spectra depending of water content and nature of solvent. For D2O calibrating plot $\text{I}_{\mathrm {Eu}}/\text{I}_{\mathrm {Tb}}$ –%H2O is linear whereas for dioxane and acetonitrile the dependence becomes linear in the coordinates $\text{I}_{\mathrm {Eu}}/\text{I}_{\mathrm {Tb}}$ -ln(%H2O). The results reveal the potential application of developed sensor for ratiometric quantitation of H2O admixtures in D2O, organic solvents, transformer oil, etc.

A solvatochromic AIE tetrahydro[5]helicene derivative as fluorescent probes for water in organic solvents and highly sensitive sensors for glyceryl monostearate

In this paper, a tetrahydro[5]helicene-based imide dye with thienyl group (THID) was studied on its solvatochromism and aggregation-induced emission (AIE) properties by dissolved in various organic solvents. The linear relationship between Stokes shift and aprotic solvent polarity parameter was well fitted with Lippert-Mataga model. Furthermore, Stokes shift also were positively correlated with the normalized molar electronic transition energy, suggested that THID exceptionally depends on solvent polarity for twisted intramolecular charge transfer. In addition, THID demonstrated typical AIE features when adding large amounts of water into good solvent. Meanwhile, it can function as intensity and wavelength-based fluorescence sensor for detecting low-level water content in water soluble solvents, even the low of detection was 0.014 vol% in ACN. Therefore, a simple and highly selective fluorescence analysis for glyceryl monostearate has been established on basis of its AIE property.

Design of dual-emission fluorescence sensor based on Cu nanoclusters with solvent-dependent effects: Visual detection of water via a smartphone

The visual detection of water in organic solvents by ratiometric fluorescence probes has attracted much attention because they can reduce environmental interference and differentiate color readily. Herein, a fast, convenient, and low-cost method of detecting water was developed based on a ratiometric fluorescence probe composed of fluorescent Cu nanoclusters (CuNCs) and carbon dots (CDs). CuNCs with solvent-dependent effects have different responses to water in various solvents while CDs are ideal fluorescence reference because of their excellent fluorescence stability. With the increase of water content in organic solvents, the ratiometric fluorescence probe exhibited an obvious color change from orange to blue and was employed for the sensitive detection of water contents via fluorescence intensity ratios (orange/blue). Smartphone as a portable tool was introduced to quantitatively analyze the visual results by acquire images, read colors, and analyze data. Moreover, the developed water sensing platform was applied to the detection of water contents in white wine and medical alcohol samples, proving its great potential in practical applications.

N-doped carbon dots with tunable emission for multifaceted application: solvatochromism, moisture sensing, pH sensing, and solid state multicolor lighting

Novel N-doped green-emitting carbon dots (N-GCDs) that were responsive to various external stimuli and had high quantum yields (QYs) for multifaceted applications were synthesized from β-resorcylic acid and ethylenediamine using a hydrothermal process followed by a reflux method. The QYs of the N-GCDs were in the range of 17.36%–48.4% and were associated with different photoluminescent color emission in different solvents. Interestingly, the as-synthesized N-GCDs exhibited strict solvent polarity-dependent switchability (solvatochromism) and multicolor excitation-wavelength-independent emission in different solvents. Sensing of an analyte based on the switching of the photoluminescence (PL) emission maxima (λmax) is always preferred over that based on fluorescence quenching to avoid complexity and confusion regarding the initial fluorescence intensity (I0) and thus make the sensing process simple, rapid, ordered, and reliable. The N-GCDs exhibited blue emission in low-polarity organic solvents, but with the increase of the trace water content in the system, the PL emission peak gradually shifted to a higher wavelength (bathochromic shift) at a single-wavelength excitation. Thus, the N-GCDs are sensitive visual probes for the fluorescence detection of the trace water content in organic solvents without sophisticated processes. They also indicate the pH-response behavior. When the pH decreased from 7.6 to 2.4, the fluorescence emission intensity decreased, with a particularly good linear relationship (R2 = 0.990) in the range of 3.8–6.2. Moreover, the polarity-dependent-emission property was observed in the solid state polymer matrices. Multicolor-emissive N-GCD/polymer films were prepared by integrating N-GCDs with the polymer matrices of different polarity, demonstrating the application of carbon dots for solid-state lighting.

A ratiometric 4-amido-1,8-naphthalimide fluorescent probe based on excimer-monomer emission for determination of pH and water content in organic solvents

The pH and water content in organic solvents are some of the most important parameters that play a key role in chemical laboratories, clinical analysis, food processing, biomedical and environmental monitoring, and life sciences. Herein we are reporting on the design, synthesis and sensor activity of a novel 4-amido-1,8-naphthalimide ratiometric fluorescent pH probe based on excimer-monomer switching mechanism. The fluorescence chemosensing behavior of the synthesized compound was studied in solvents of different polarity and the results obtained clearly demonstrates the great opportunity of the novel probe selectively to determine pH in aqueous solutions and water content in organic environment.

Measurement and Correlation of Solubility of Calcium Formate (Form α) in Different Binary Solvent Mixtures at Temperatures from 283.15 to 323.15 K

The solubility of calcium formate (form α) in four different binary solvent mixtures (methanol + water, ethanol + water, n-propanol + water, and acetone + water) from 283.15 to 323.15 K was measured by a static equilibrium method under atmospheric pressure. Results indicated that the solubility increased with the increasing temperature and water content in binary mixed solvents. The modified Apelblat equation, the combined nearly ideal binary solvent/Redlich-Kister equation, and the Jouyban–Acree equation were applied for the correlation of experimental solubility, among which the modified Apelblat equation was found to be the best fitting model for the crystallization of calcium formate (form α). This experimental data can be a fundamental guide to choose a suitable crystallization process for calcium formate in industry.

Coordination of mycotoxins with lanthanides in luminescent complexes.

The ability of several chelating mycotoxins to form coordination complexes with the lanthanide metals europium and terbium was explored. The mycotoxins examined included ochratoxin A, citrinin, cyclopiazonic acid (CPA), kojic acid, and tenuazonic acid (TeA). Of these compounds, TeA and CPA resulted in the greatest luminescence. Parameters influencing luminescence of TeA were investigated further. These included the type of lanthanide and its concentration, certain environmental factors, and the effect of competing metal cations. Of the two lanthanide metals, the terbium coordination complex (TeA-Tb3+) showed greater luminescence relative to the europium complex (TeA-Eu3+). The effects of solvent type, water content, and pH on the TeA-Tb3+ system suggested that optimal conditions for luminescence were in 90% methanol with 10% aqueous buffer at pH3. In competitive assays, the luminescence of the TeA-Tb3+ complex decreased as the concentration of competing metal cations increased. Among the cations tested, Cu2+ was the best inhibitor followed by Al3+, Au3+, Fe3+, Co2+, Mn2+, Mg2+, and Ca2+. Two cations, Na+ and K+, showed no significant inhibition. This is the first report to describe the coordination of the metal-chelating mycotoxin TeA with lanthanides and the ability of TeA to serve as an "antenna" for the efficient transfer of energy to the lanthanide with resulting luminescence. Understanding the ability of mycotoxins such as TeA to chelate metals provides insight into how they exert their toxic effects.

Excited State Intramolecular Proton Transfer Plus Aggregation-Induced Emission-Based Diketopyrrolopyrrole Luminogen: Photophysical Properties and Simultaneously Discriminative Detection of Trace Water in Three Organic Solvents.

Developing solid state near-IR (NIR) emitters and simultaneously discriminative detection of trace water in organic solvents has long been a significant challenge. In this work, a novel diketopyrrolopyrrole-based luminogen (DPP1) with excited state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) characteristics has been designed and synthesized. Its amorphous and crystal solids show red and NIR-emissive fluorescence at 625 and 675 nm, respectively. When DPP1 reacts with fluoride anion, the resulting system (DPP1·F) can discriminatively detect the water content in aprotic solvents with colorimetric and fluorescent dual modes. Distinct fluorescent responses of "turn-on", "ratiometric turn-off", and "ratiometric turn-on" and low limits of detection of 0.0064, 0.042, and 0. The water-induced sensitive and fast change in THF was applied to the determination of water in foodstuffs in practical solid state indicator paper strips.

Ratiometric and Turn-On Luminescence Detection of Water in Organic Solvents Using a Responsive Europium-Organic Framework.

The development of simple, rapid-response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual-emitting europium-organic framework (Eu-MOF), which is assembled from a purposely selected 2-aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched-on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu3+ emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn-on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu-MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05-10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l'Eclairage (CIE) chromaticity coordinate. The present Eu-MOF sensor featuring high sensitivity and reusability, self-calibration, simple fabrication and operation, and capability for real-time and in situ detection is expected to have practical applications in water analysis for industrial processes.

Deep eutectic solvent as a green solvent for enhanced extraction of narirutin, naringin, hesperidin and neohesperidin from Aurantii Fructus.

In the present study, a green and efficient extraction method using deep eutectic solvents as extraction solvent was developed for extracting the four major active compounds narirutin, naringin, hesperidin and neohesperidin from Aurantii Fructus. A series of tunable deep eutectic solvents were prepared and investigated by mixing choline chloride or betaine to different hydrogen-bond donors, and betaine/ethanediol was found to be the most suitable extraction solvent. To achieve the best extraction yield, the primary factors affecting the extraction efficiency, such as hydrogen-bond acceptor/hydrogen-bond donor ratio, water content in deep eutectic solvents, extraction temperature, solid/liquid ratio and extraction time, were investigated. The optimal extraction conditions were 40% of water in betaine/ethanediol (1:4) at 60°C for heated extraction of 30min and solid/liquid ratio 1:100g/mL. Under the optimum extraction condition, the extraction yields of narirutin, naringin, hesperidin, and neohesperidin were 8.39±0.61, 83.98±1.92, 3.03±0.35 and 35.94±0.63mg/g, respectively, which were much higher than those of methanol as extraction solvent (5.5±0.48, 64.23±1.51, 2.16±0.15 and 30.14±0.62mg/g). The present results showed that deep eutectic solvents could be promising green and efficient solvents for extraction of the bioactive ingredients from traditional Chinese medicine.

Synthesis and photophysical properties of novel 1,8-naphthalimide light-harvesting antennae based on benzyl aryl ether architecture

Two novel benzyl aryl ether light-harvesting antennae accomplishing high effective energy transfer, core and peripherally decorated with fluorescent 1,8-naphthalimide units were successfully synthesized. The peripheral blue-emitting benzyl aryl ether intermediate wedge showed considerable probe potential for determination of water content in organic solvents probably as a result of a TICT process. The core of one of the two light-harvesting antennae was configured on the “fluorophore-spacer-receptor” format. Due to the simultaneous operation of FRET and PET processes that system showed excellent pH sensing characteristics and high potential as a probe for monitoring the pH variations in environmental and biological samples.

A simple method to determine the water content in organic solvents using the 1H NMR chemical shifts differences between water and solvent

A simple and general method which relies on chemical shift difference between water and solvent peaks in 1H NMR spectroscopy has been developed for the determination of water content in organic solvent. As the water content is increased, the water proton peak is shifted to down-field because the water is involved in the more hydrogen bonding. The linear relation between water content and chemical shift difference was used to assess the water content in organic solvent. The intrinsic water and solvent proton peak was used, thus no additional reagents was necessary. The developed method has been applied to six organic solvents having various chemical properties. Furthermore, temperature effect was investigated and correction factor was evaluated. We propose that this new method will be useful for wide range of applications requiring accurate and convenient assessment of water content in organic solvents.

Solvent Water Content as a Factor in the Design of Metal Ion Extraction Systems Employing Ionic Liquids

ABSTRACTIn the extraction of strontium nitrate from aqueous nitric acid solutions into a series of hydrophobic N-(1-hydroxyalkyl)-N’-alkylimidazolium bis[(trifluoromethyl)sulfonyl]imides by dicyclohexano-18-crown-6, a correlation has been demonstrated between the conditional extraction constant of strontium (K’ex,Sr) and the concentration of water in the equilibrated ionic liquid (IL) phase. Despite the absence of a hydroxyl group on the IL cation, essentially the same relationship is observed for the analogous N,N’-dialkylimidazolium ILs. In both instances, the correlation is attributed to the coextraction of the hydrated nitrate ion and its solvation by the hydrated diluent. Transitions of water in the attenuated total reflectance-infrared spectra of the ILs are consistent with the existence of multiple states of water. The extraction efficiency for a given water content is greater for the ILs examined than for conventional solvents (i.e., n-alcohols). When coupled with existing knowledge of the factors influencing cation partitioning into ILs, these results provide insight into the IL structural characteristics required to effect efficient metal ion extraction from acidic media.

The coumarin conjugate: synthesis, photophysical properties and the ratiometric fluorescence response to water content of organic solvent

A new fluorescent probe based on coumarin conjugate has been synthesized which shows high quantum yield because of strong ICT effect. The absorption and fluorescence spectra of probe were measured in a variety of solvents and the Stokes shifts were found to be in linear relationship with the orientation polarizability of the solvents. The fluorescence intensity of probe decreased with a rise in water content which could be an effective fluorescence water sensor in organic solvents. Moreover, the probe presents a highly linear ratiometric fluorescence response to water content under the excitation of ultraviolet light. The detection results by the ratiometric fluorescence probe are in good agreement with that by the well-established standard Karl Fischer method. This ratiometric fluorescent probe provides another accessible tool for the quantitative determination of water content and may replace the Karl Fischer method for specific applications.

Anodic Reactions and the Corrosion of Copper in Deep Eutectic Solvents

An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2− complex. In pure ethaline the current efficiency of the anodic process is 100% and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday's law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: CuCl42− + Cu → 2CuCl2−. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42− complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that complex dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic.