Water Content In Organic Solvents Research Articles

Blue luminescent N,S-doped carbon dots encapsulated in red emissive Eu-MOF to form dually emissive composite for reversible anti-counterfeit ink.

Lanthanide metal-organic frameworks (Ln-MOFs) have demonstrated great potential in luminescence sensing and optical anti-counterfeiting. High-security anti-counterfeiting technology is of great importance and requires the development of universal luminescent materials with multiple modes of emission and adjustable photoluminescence. Herein, a 3D red light emission microporous europium(iii) metal-organic framework [Eu3(OH)(1,3-db)2(H2O)4]·3H2O (1) (1,3-db = 1,3-di(3',5'-dicarboxylpheny) benzene) was constructed from a zigzag [Eu3(COO)8] chain and π-electron-rich terphenyl-tetracarboxylate. Notably, the quenched fluorescence of 1 under hydrogen chloride vapor could be recovered upon fuming by a vapor of Et3N. Most strikingly, the strong blue light emission by nitrogen and sulfur co-doped carbon dots (N,S-CDs) could be encapsulated in 1 to generate a dual-emission composite, namely, N,S-CDs@Eu-MOF, which shows solvent-dependent photoluminescence: N,S-CD-related blue luminescence in water and Eu-MOF-related red emission in organic solvents. Taking advantage of the above unique reversible fluorescent behavior, Eu-MOF and N,S-CDs@Eu-MOF are prepared as fluorescent high-security inks to achieve data encryption and decryption on specific flower patterns.

Supramolecular gel formation regulated by water content in organic solvents: self-assembly mechanism and biomedical applications.

As one of the most important and fruitful methods, supramolecular self-assembly has a significant advantage in designing and fabricating functional soft materials with various nanostructures. In this research, a low-molecular-weight gelator, N,N′-di(pyridin-4-yl)-pyridine-3,5-dicarboxamide (PDA-N4), was synthesized and used to construct self-assembled gels via a solvent-mediated strategy. It was found that PDA-N4 could form supramolecular gels in mixed solvents of water and DMSO (or DMF) at high water fraction (greater than or equal to 50%). By decreasing the water fraction from 50% to 30%, the gel, suspension and solution phases appeared successively, indicating that self-assembled aggregates could be efficiently modulated via water content in organic solvents. Moreover, the as-prepared PDA-N4 supramolecular gels not only displayed solid-like behavior, and pH- and thermo-reversible characteristics, but also showed a solution–gel–crystal transition with the extension of aging time. Further analyses suggested that both the crystal and gel had similar assembled structures. The intermolecular hydrogen bonding between amide groups and the π–π stacking interactions between pyridine groups played key roles in gel formation. Additionally, the release behavior of vitamin B12 (VB12) from PDA-N4 gel (H2O/DMSO, v/v = 90/10) was evaluated, and the drug controlled release process was consistent with a first-order release mechanism. The human umbilical venous endothelial cell culture results showed that the PDA-N4 xerogel has good cytocompatibility, which implied that the gels have potential biological application in tissue engineering and controlled drug release.

Photophysical and crystallographic study of three integrated pyrazolo[1,5-a]pyrimidine–triphenylamine systems

Three new intramolecular charge transfer (ICT) fluorophores having triphenylamine and pyrazolo[1,5-a]pyrimidine moieties 4a-c were synthesized, and their structures were solved by X-ray crystallography (XRC). Compounds 4a, 4b and 4c crystallize in the tetragonal P42/n, triclinic P-1 and monoclinic P21/c space groups with calculated CE-B3LYP structural energies of −104.3, −125.6 and −123.8 kJ/mol, respectively. Substituents effect on molecular and photophysical properties of 4a-c was studied in both solution and solid-state through fluorescence, UV–vis, XRC, and computational methods. The 2-phenyl (4b) and 2-anisyl (2c) derivatives showed better absorption coefficient (4b, ε = 76400 → 119600 M−1cm−1 and 4c, ε = 66200 → 89200 M−1cm−1) than 4a (2-Me, ε = 9933 → 21667 M−1cm−1), while the relative quantum yield (φ) in solvents of diverse polarity is as high as φ = 0.98 for 4a, φ = 0.86 for 4b and φ = 0.83 for 4c. For these dyes, Lippert–Mataga correlation were used to estimate the difference between the excited and ground state dipole moments (Δμ), being 4b the one that suffer the bigger changes with a Δμ οf 26.9 D. Probe 4c is found to be useful as a fluorescent indicators for the qualitative sensing of water content in organic solvents. The solid-state emission data reveal that the antiparallel molecular packing of the crystal structure for 4a-c, with energy framework diagrams influenced mainly by dispersion forces, could disturbs the photophysical properties by changing the donor-acceptor intramolecular coupling. Therefore, the combination of these XRC and photophysical results may constitute in a key input for designing applications in material science.

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

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.

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.

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.

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.

Chalcone based ion-pair recognition towards nitrates and the application for the colorimetric and fluorescence turn-on determination of water content in organic solvents

This article describes a novel ion-pair recognition mode of a molecular probe (C-1) bearing chalcone moiety. C-1 can bind to metal nitrates selectively (metal = Zn2+, Ni2+, Co2+, Cd2+) with remarkable color change from yellow to purple. The mechanism was investigated via experimental and theoretical approaches. The results show that C-1 coordinate with metal ions by stoichiometric ratio 2:1, the nitrate anion binds with metal ion via electrostatic interaction, and binds with ligand via supramolecular interactions. Furthermore, the selected two-component sensor, C-1/Ni(NO3)2, can detect water content in acetone, acetonitrile, ethanol and isopropanol with low detection limit by both colorimetric and fluorescence turn-on approach. The sensor has favorable linear relationships with water content within the range 0–10% in the above four solvents, and the detection limit in acetone, acetonitrile, ethanol and iso-propanol is 0.20%, 0.38%, 0.24% and 0.09%, respectively, showing great potential for water content monitoring.

Efficient Reversible Optical Sensing of Water Achieved through the Conversion of H‐Aggregates of a Merocyanine Salt to J‐Aggregates

AbstractA stable MC (merocyanine)‐spiropyran as p‐toluenesulfonate salt was synthesized. The structure of the merocyanine salt form of the spiropyran was established by using IR, 1H‐NMR, 13C‐NMR, 2D‐NMR and HR‐MS spectroscopic techniques. The MC salt was employed as an optical probe for the detection of trace water content in the organic media using the naked eye, UV‐Visible and fluorescence spectroscopic techniques. The DLS and TEM measurements were used to support the aggregation and disaggregation of the MC salt form. The results established the conversion of H‐ aggregates to J‐ aggregates can be used for the efficient detection of trace water content in organic media. The optical probe was further used to sense and quantify water molecules associated with the metal salts. The probe can be used multiple times for sensing water. The results provide insightful opportunities for practical applications of sensing trace water content in organic solvents and coordinated to metal ions.

Assessing the Potential of Organic Solvents on Total Petroleum Hydrocarbon Extraction from Diesel-Contaminated Soils

The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study.

A dual-emission probe to detect moisture and water in organic solvents based on green-Tb3+ post-coordinated metal-organic frameworks with red carbon dots.

Using p-phenylenediamine as a precursor, p-carbon dots (p-CDs) with strong red-light emission were encapsulated into a metal-organic framework (MOF) followed by introduction of green light-emitting Tb3+ to form a two-color light-emitting hybrid (Tb3+@p-CDs/MOF). The as-prepared fluorescent-functionalized MOF not only maintained the excellent optical properties of p-CDs and Tb3+ to give strong emission, but also had good chemical and physical properties. The chosen p-CDs were aggregated readily in water, which led to only very weak photoluminescence, whereas the opposite effect was noted in the organic solvents ethanol, dimethylformamide and cyclopropane. Therefore, the as-prepared hybrid showed different color light emission in water or organic solvents, and acted as a ratiometric and colorimetric fluorescent probe to detect water content in organic solvents. Moreover, this hybrid also served as a ratiometric luminescent sensor for detection of relative humidity (RH): the ratio of light intensity at 545 nm to that at 605 nm increased linearly with increasing RH from 33.0% to 85.1% in the atmosphere.

A fluorescent ratiometric sensor based on covalent immobilization of chalcone derivative and porphyrin Zinc for detecting water content in organic solvents

This paper describes a fluorescent ratiometric sensor for water content determination in organic solvents. Two different compounds, 4′-N, N-dimethylamino-4-methylacryloylamino chalcone (DMC) and 5, 10, 15, 20-tetra-(4-methylacryloylaminophenyl)porphyrin Zinc (TMAPPZn), were synthesized as indicators for fluorescence ratiometric water sensing. DMC is a fluorescence indicator with charge donor parts and acceptor parts and sensitive to solvent polarity and water content. The fluorescence intensity of TMAPPZn is insensitive to the water content lower than 10% (v/v) water content and employed as the reference indicator. The use of TMAPPZn as a reference indicator resulted in a more stable signal due to minimizing the effects of fluctuations of light intensity, fluorophore bleaching, background signal, and so forth. DMC and TMAPPZn were photo-copolymerized on the silanized glass surface to prevent leakage of the fluorescence indicators. Three organic solutions (ethanol, acetone, and tetrahydrofuran) were used to verify the performances of the proposed sensor, and the sensor exhibited a good linearity in the range 0–10% (v/v) water content with detection limits of 0.0097%, 0.011%, and 0.017% for ethanol, acetone, and tetrahydrofuran, respectively. The ratiometric sensor was characteristic of satisfactory reproducibility, reversibility, short response time. The sensing membrane was found to have a lifetime of two month. We carried out preliminary spiking experiments on the actual samples, and the spiked recoveries were of 99.2–102.0%.

Hydrochromic Approaches to Mapping Human Sweat Pores.

Hydrochromic materials, which undergo changes in their light absorption and/or emission properties in response to water, have been extensively investigated as humidity sensors. Recent advances in the design of these materials have led to novel applications, including monitoring the water content of organic solvents, water-jet-based rewritable printing on paper, and hydrochromic mapping of human sweat pores. Our interest in this area has focused on the design of hydrochromic materials for human sweat pore mapping. We recognized that materials appropriate for this purpose must have balanced sensitivities to water. Specifically, while they should not undergo light absorption and/or emission transitions under ambient moisture conditions, the materials must have sufficiently high hydrochromic sensitivities that they display responses to water secreted from human sweat pores. In this Account, we describe investigations that we have carried out to develop hydrochromic substances that are suitable for human sweat pore mapping. Polydiacetylenes (PDAs) have been extensively investigated as sensor matrices because of their stimulus-responsive color change property. We found that incorporation of headgroups composed of hygroscopic ions such as cesium or rubidium and carboxylate counterions enables PDAs to undergo a blue-to-red colorimetric transition as well as a fluorescence turn-on response to water. Very intriguingly, the small quantities of water secreted from human sweat pores were found to be sufficient to trigger fluorescence turn-on responses of the hydrochromic PDAs, allowing precise mapping of human sweat pores. Since the hygroscopic ion-containing PDAs developed in the initial stage display a colorimetric transition under ambient conditions that exist during humid summer periods, a new system was designed. A PDA containing an imidazolium ion was found to be stable under all ambient conditions and showed temperature-dependent hydrochromism corresponding to a colorimetric change near body temperature. This feature enables the use of this technique to generate high-quality images of sweat pores. This Account also focuses on the results of the most recent phase of this investigation, which led to the development of a simple yet efficient and reliable technique for sweat pore mapping. The method utilizes a hydrophilic polymer composite film containing fluorescein, a commercially available dye that undergoes a fluorometric response as a result of water-dependent interconversion between its ring-closed spirolactone (nonfluorescent) and ring-opened fluorone (fluorescent) forms. Surface-modified carbon nanodots (CDs) have also been found to be efficient for hydrochromic mapping of human sweat pores. The results discovered by Lou et al. [ Adv. Mater. 2015 , 27 , 1389 ] are also included in this Account. Sweat pore maps obtained from fingertips using these materials were found to be useful for fingerprint analysis. In addition, this hydrochromism-based approach is sufficiently sensitive to enable differentiation between sweat-secreting active pores and inactive pores. As a result, the techniques can be applied to clinical diagnosis of malfunctioning sweat pores. The directions that future research in this area will follow are also discussed.

Two novel dyes containing spirobifluorene and triphenylamine: Synthesis, one- and two-photon excited fluorescence and applications as probes for silver ions, water and cell imaging

Two fluorophores, SPF-TNS and SPF-TBB, with electron-rich triphenylamine groups and Ag+ receptor units on the respective biphenyl branches of 9,9′-spirobifluorene were synthesized. They exhibit strong one- and two-photon excited fluorescence, and the two-photon absorption cross-section values are 665 GM for SPF-TNS and 355GM for SPF-TBB. The probing behaviors toward metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TNS and SPF-TBB exhibit distinct fluorescent quenching in the presence of silver ions that can be used for highly sensitive and selective naked-eye detection of Ag+. The one-photon excited fluorescence of SPF-TBB can be made to measure water content of organic solvents. The detection limits were calculated to be 0.04% for THF and 0.03% for 1,4-dioxane. The two-photon scanning microscopy experiments suggest that SPF-TNS is a promising label potentially applicable for the tracking of biomolecules.

Dual-Emission of Lanthanide Metal–Organic Frameworks Encapsulating Carbon-Based Dots for Ratiometric Detection of Water in Organic Solvents

Nitrogen and sulfur codoped carbon-based dots (N,S-CDs) with strong blue light emission are encapsulated into red light-emitting europium metal-organic frameworks (Eu-MOFs) to form two color light-emitting nanohybrids (Eu-MOFs/N,S-CDs). In organic solvents, the encapsulated N,S-CDs are aggregated and confined in the cavities of the Eu-MOFs, exhibiting only a very weak photoluminescence (PL) signal. Therefore, the nanohybrids show red light emission of the Eu-MOFs. Contrarily, when the Eu-MOFs/N,S-CDs are dispersed in water, the encapsulated N,S-CDs are released into solution while the red light emission of the Eu-MOFs is quenched due to the effect of O-H oscillators. The nanohybrids are used as the probe for the water content in organic solvents. Take ethanol as an example; as the water content is increased from 0.2 to 30%, the nanoprobe provides distinguishable PL color change. The ratio of light intensity at 420 nm to that at 623 nm (I420/I623) increases linearly with increasing water content in the range from 0.05 to 4% with a low detection limit of 0.03%.

A phosphorescent Ir(iii) complex with formamide for the luminescence determination of low-level water content in organic solvents

A novel formamide-containing Ir(iii) complex was designed and synthesized for the determination of water content with low LOD and LOQ by a time-resolved luminescence technique.