Water Organic Solvents Research Articles

Microencapsulation: A Promising Technique for Controlling Drug Delivery

Microencapsulation is a well-established process of enveloping or surrounding one substance into another substance which gives capsules having range from less than one micron to several hundred microns in size. One of the highly efficiently method is micro encapsulation, micro particles or microspheres rely upon various factors like solubility of polymer in solvent, concentration of polymer, solubility of organic solvent in water, rate of solvent removal etc. Microparticulate drug delivery systems are an interesting and promising option when developing an oral controlled release system. The objective of this paper is to take a closer look at microparticles as drug delivery devices for increasing efficiency of drug delivery, improving the release profile and drug targeting. In order to appreciate the application possibilities of microcapsules in drug delivery, some fundamental aspects are briefly reviewed. The controlled release drug delivery system, releases the active drug or medicament at a predetermined rate targeting to specific site over a prolonged period of time.

Solvatochromic covalent organic frameworks for the low-level determination of trace water in organic solvents

Here we report a rational design and preparation of luminescent COFs via the synergetic interaction of electron-rich and electron-deficient moieties. 4,4′,4′-(1,3,5-triazine-2,4,6-triyl) trianiline (TTA) with the electron-deficient unit and 2,6-diformyl-4-methylphenol (Dp) with the electron-rich moiety and −OH group were employed to synthesize the imine-linked DpTTA-COF. The intramolecular charge transfer enables DpTTA-COF to present a strong solvent polarity-dependent color change, based on which a solvatochromic sensor was successfully established. We demonstrate an emission wavelength and intensity dual-mode photoluminescent sensor for the detection of trace water in organic solvents with good sensitivity, reversibility and stability. In addition, the dual-signal solvatochromic sensor is also capable for organic solvents decoding. This work proposes a new strategy for the design and preparation of COFs with fascinating solvatochromic effect. This strategy could extend the application field of COFs by the integration of functional groups, affinity, and structural selectivity.

Organic solvent reverse osmosis (OSRO) for the recovery of hemicellulosic derivatives after wood-pulping with a deep eutectic solvent

This work investigates the recovery of a deep eutectic solvent (DES) used for pulping wood, by removing remnant hemicellulosic derivatives using reverse osmosis (RO). Xylose and its dehydration product furfural are considered representative hemicellulosic derivatives, and a lactic acid-choline chloride DES was used. Various diluting solvents were considered for the RO feed, namely pure water and binary water-organic solvent (ethanol, acetone, and methanol) mixtures. The results in this work show that the xylose rejection is high in water as well as in the presence of organic solvents such as acetone (with 97% rejection in aqueous acetone solvent and 95% in pure water using the RO membrane). On the other hand, furfural is rejected poorly by the RO membrane in all media (below 60% in all solvents). Finally, based on these results, a separation scheme was proposed to attain a complete mass recovery of each component of this mixture.

Detection of Trace Amounts of Water in Organic Solvents by DNA-Based Nanomechanical Sensors

The detection of trace amounts of water in organic solvents is of great importance in the field of chemistry and in the industry. Karl Fischer titration is known as a classic method and is widely used for detecting trace amounts of water; however, it has some limitations in terms of rapid and direct detection because of its time-consuming sample preparation and specific equipment requirements. Here, we found that a DNA-based nanomechanical sensor exhibits high sensitivity and selectivity to water vapor, leading to the detection and quantification of trace amounts of water in organic solvents as low as 12 ppm in THF, with a ppb level of LoD through their vapors. Since the present method is simple and rapid, it can be an alternative technique to the conventional Karl Fischer titration.

The use of zeolite 13X as a stationary phase for direct determination of water in organic solvents by high-performance liquid chromatography

High-performance liquid chromatography (HPLC) method for direct determination of water impurities in various organic solvents using a column (50 × 4.6 mm, ID) packed with 5 μm faujasite and methanol as an eluent was developed. Detection of the water peaks was performed by using either refractometric or indirect spectrophotometric method at 204 nm. In the first case the limit of detection (LOD) and limit of quantitation (LOQ) were 0.001 wt% and 0.0033 wt%, respectively for a sample volume of 20 μL. A linear calibration plot (R2 = 0.9998) for the water content between 0.01 and 9.55 wt% was obtained. The developed method was applied for the direct analysis of various polar organic solvents including acetonitrile, nitromethane, 1,4-dioxane, 2-ethoxyethanol, methanol, dimethyl sulfoxide (DMSO), ethanol and 2-propanol.

Oxygen ether chain containing covalent organic frameworks as efficient fluorescence-enhanced probe for water detection

Three covalent organic frameworks (COFs) named as TPPA-DTM-COF, TPPA-BMTP-COF and TPPA-BETP-COF with different lengths of oxygen ether chains were successfully synthesized by the condensation between 4,4′,4''-(1,3,5-triazine-2,4,6-triyl)trianiline (TPPA) with 2,5-dimethoxyterephthalaldehyde (DTM), 2,5-bis(2-methoxyethoxy)terephthalaldehyde (BMTP) and 2,5-bis(2-(2-methoxyethoxy)ethoxy)terephthalaldehyde (BETP), respectively, which have high crystallinity, large specific surface area and high thermochemical stability. The fluorescence performance of the as-prepared COFs in acetonitrile showed that the longer the oxygen ether chain, the stronger the fluorescence intensity, this may be related to the inhibition of aggregation-caused quenching (ACQ) effect with the increase of interlayer spacing. The resulting COFs also exhibited different emission in different solvents, and their fluorescence intensity has a significant and rapid response to water in organic solvents. Among them, TPPA-DTM-COF shows the most stable fluorescence emission and good dispersion in organic solvents. Its fluorescence intensity is linear with water content in acetonitrile ranging from 0% to 15% (V/V), and the detection limit was calculated to be 0.27%. In addition, the detection limits of COF in ethanol, THF and DMF are 0.15%, 0.43% and 0.39%, respectively. The mechanism of TPPA-DTM-COF detect water with fluorescence “on” may be that the water can form hydrogen bonds with N and O atoms on the skeleton of TPPA-DTM-COF, which enhanced the stability of the excited states of the COFs, thereby enhancing the intramolecular charge transfer (ICT) in the excitation state, leading to the enhancement of fluorescence. The superior properties of TPPA-DTM-COF inducing the as-prepared COF has a great prospect for trace amount water detection in organic solvents in the form of fluorescence enhancement.

Dual-Beam Photothermal Spectroscopy Employing a Mach-Zehnder Interferometer and an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents.

We report on a mid-infrared (mid-IR) photothermal spectrometer for liquid-phase samples for the detection of water in organic solvents, such as ethanol or chloroform, and in complex mixtures, such as jet fuel. The spectrometer is based on a Mach-Zehnder interferometer (MZI) employing a He-Ne laser, a mini-flow cell with two embedded channels placed in the interferometer's arms, and a tunable external cavity quantum cascade laser (EC-QCL) for selective analyte excitation in a collinear arrangement. In this study, the bending vibration of water in the spectral range 1565-1725 cm-1 is targeted. The interferometer is locked to its quadrature point (QP) for most stable and automated operation. It provides a linear response with respect to the water content in the studied solvents and photothermal analyte spectra, which are in good agreement with FTIR absorbance spectra. The method is calibrated and validated against coulometric Karl Fischer (KF) titration, showing comparable performance and sensitivity. Limits of detection (LODs) for water detection in the single-digit ppm range were obtained for chloroform and jet fuel due to their low background absorption, whereas lower sensitivity has been observed for water detection in ethanol due to pronounced background absorption from the solvent. In contrast to KF titration, which requires toxic reagents and produces waste, the developed method works reagent-free. It can be applied in an online format in the chemical industry as well as for fuel quality control, being industrial applications where traces of water need to be accurately determined, preferably in real-time. It thus holds great promise as a green alternative to the offline KF titration method, which is the current standard method for this application.

Fluorescence ‘‘turn-on’’ probe for the selective detection of water in organic solvents based on functionalized mesoporous silica

A fluorescence ‘‘turn-on’’ probe, namely, TTA-SBA-15, for the selective detection of water (H2O) was designed by grafting terthiophene fluorophore onto ethylenediamine functionalized mesoporous SBA-15 silica. The maximum fluorescence emission peak of TTA-SBA-15 ranged from 462 nm (toluene) to 525 nm (methanol) in various organic solvents. No fluorescence was observed in H2O due to the donor-excited photoinduced electron transfer mechanism, in which terthiophene acted as the donor and the amino group acted as the acceptor. Upon adding trace amounts of H2O into the TTA-SBA-15 suspensions dispersed in various organic solvents, TTA-SBA-15 was successfully applied as a ‘‘turn-on’’ fluorescent probe for the quantitative determination of trace H2O in organic solvents with high sensitivity and low detection limit. To demonstrate the selective detection mechanism of TTA-SBA-15 for H2O, the fluorescent spectra of two control materials (TT-SBA-15 and PyA-SBA-15) were also investigated in H2O and various organic solvents. The experimental results indicated that the terthiophene fluorophore and amine functional group on TTA-SBA-15 contributed to the H2O selectivity, highlighting the structure-activity relationships in developing organic functionalized mesoporous silica for potential applications.

Amphiphilic Sugar Derivatives Linked with Gallic Acid Bearing Tris-alkoxy Groups throughL-Lysine Linkage: Self-assembly and Efficient Dye Removal in Water-organic Solvent Biphasic System

Amphiphilic small molecules (1), constructed from two sugar moieties and a gallic acid bearing tris-alkoxy group via an L-lysine linkage, were synthesized. Amphiphile (1a) exhibited fibrous self-assembly through emulsification in a water-organic solvent biphasic system and showed efficient removal of various organic dyes with varying degrees of hydrophobicity from the aqueous phase.

Nanofiltration membranes composed of carbonized giant cane and Pongamia meal binder for ion sieving in water and molecular sieving in organic solvents

Climate change and other environmental problems necessitate the use of renewable resources and the development of sustainable technologies. Thus, giant cane, which is naturally abundant, and a plant-based binder extracted from Millettia pinnata seeds were used to fabricate carbon-based composite membranes. A continuous and uniform layer of a carbonized giant cane was formed on a porous support using a simple filtration method. The hardness of the membranes increased with the carbon content. The increase in the carbon content in the membrane yielded a looser and more selective nanofiltration membrane; the water permeance increased from 13 to 19 L m−2 h−1 bar−1 and the NaCl/MgSO4 selectivity doubled from 10 to 20. Similarly, the rejection of five different salts and seven organic molecules decreased in water and acetone, respectively. The acetone permeance and molecular weight cutoff increased from 7 to 12 L m−2 h−1 bar−1 and from 577 to 795 g mol−1, respectively. The long-term performance tests on the membranes indicated a stable rejection of higher than 99% for rose bengal and a stable steady-state flux over a week of continuous filtration. The membranes exhibited good stability and high permeance in different organic solvents, including a harsh polar aprotic solvent, i.e., N,N-dimethylformamide. The toxicity of the giant cane carbon and the binder was examined via a cytotoxicity assay using NIH 3T3 cells. No toxicity was observed for either material. This study proposes a sustainable route for preparing aqueous and organic solvent nanofiltration membranes using natural nontoxic resources.

Photophysical properties and aggregation behavior of diethylene glycol substituted pyropheophorbide-a in cationic surfactant solutions

The aggregation behavior of a novel amphiphilic photosensitizer - pyropheophorbide-[Formula: see text] 17-diethylene glycol ester 1 was studied in aqueous and aqueous-organic mixtures by means of steady-state absorption and fluorescence emission spectroscopy. The formation of [Formula: see text]-aggregates with a bathochromic shift of the absorption bands, weak fluorescence and resonance enhancement of the light scattering was observed in the mixed water-organic solvents. Solubilization studies in micellar cationic surfactant solutions of alkyl trimethylammonium bromides (C[Formula: see text]TAB) and alkyl triphenylphosphonium bromides (C[Formula: see text]TPPB) resulted in the most effective stabilization of the fluorescent monomolecular form of 1 in C[Formula: see text]TPPB micelles. It was shown that [Formula: see text]-aggregate formation in submicellar surfactant solutions is the initial stage of the solubilization process, which significantly increases in phosphate buffer medium at pH 7.4. Fluorescence lifetime ([Formula: see text] of 1 in DMSO was found to be 7.4 ns, fluorescence quantum yield - 34% and singlet oxygen quantum yield - 62%. The results obtained indicate the need for further studies of compound 1 solubilized in C[Formula: see text]TPPB micelles as the most promising prototype of the drug formulation for mitochondria-targeted photodynamic therapy of cancer.

Recovery of unsaturated polyester resin into oligomer for preparation of oil-water separation aerogel

The accumulation of plastic waste has become a serious environmental pollution problem. To achieve the sustainable use of energy and the conservation of resources, it is an effective solution to convert plastics into valuable chemicals. In this work, the water-soluble oligomer of unsaturated polyester resins (LMUPR) was obtained by cleavage of the ester bonds from unsaturated polyester resins. The degradation was carried out by the one-pot method in n-butanol at 80°C for 1 h with potassium hydroxide acting as a catalyst. The LMUPR can be separated by centrifugation with a yield of 98%. The LMUPR was integrated with carboxylated chitosan and N, N-Methylene-Bis-Acrylamide to form aerogels via freeze drying. The hydrophobic oleophilic aerogel (water contact angle is 131°) was prepared by surface coating of waste polyethylene solution, which can selectively adsorb a variety of oils and organic solvents in water, and showed good adsorption capacity and cycle performance. In addition, due to the retention of the properties of unsaturated polyester resins, it shows good acid and alkali resistance and compression resistance (compressive strength 310.5 kPa). This work provides new raw materials for the synthesis of aerogels and a strategy for converting waste plastics into high-value-added adsorption materials.

Evolution of Transient Luminescent Assemblies Regulated by Trace Water in Organic Solvents.

Trace water in organic solvents can play a crucial role in the construction of supramolecular assemblies, which has not gained enough attention until very recent years. Herein, we demonstrate that residual water in organic solvents plays a decisive role in the regulation of the evolution of assembled structures and their functionality. By adding Mg(ClO4)2 into a multi-component organic solution containing terpyridine-based ligand 3Tpy and monodentate imidazole-based ligand M2, the system underwent an unexpected kinetic evolution. Metallo-supramolecular polymers (MSP) formed first by the coordination of 3Tpy and Mg2+, but they subsequently decomposed due to the interference of M2, resulting in a transient MSP system. Further investigation revealed that this occurred because residual water in the solvent and M2 cooperatively coordinated with Mg2+. This allowed M2 to capture Mg2+ from MSP, which led to depolymerization. However, owing to the slow reaction between trace water/M2/Mg2+, the formation of MSP still occurred first. Therefore, water regulated both the thermodynamics and kinetics of the system and was the key factor for constructing the transient MSP. Fine-tuning the water content and other assembly motifs regulated the assembly evolution pathway, tuned the MSP lifetime, and made the luminescent color of the system undergo intriguing transition processes over time.

Enhancing the Recovery of Bioactive Compounds of Soybean Fermented with Rhizopus oligosporus Using Supercritical CO2: Antioxidant, Anti-Inflammatory, and Oxidative Proprieties of the Resulting Extract.

The aim of the present study was to evaluate the use of supercritical CO2 combined with cosolvent for the recovery of bioactive compounds of soybean fermented with Rhizopus oligosporus NRRL 2710. Soxhlet extractions using seven different organic solvents (n-hexane, petroleum ether, ethyl acetate, acetone, ethanol, methanol, and water) were initially performed for comparative purposes. The extracts obtained were characterized by physicochemical, antioxidant, total phenolic, and oxidative proprieties. For the Soxhlet extractions, the highest and lowest yields obtained were 45.24% and 15.56%, using methanol and hexane, respectively. The extraction using supercritical CO2 combined with ethanol as a static modifier (scCO2 + EtOH) presented, at a high pressure (25 MPa) and temperature (80 °C), a phenolic compound content of 1391.9 μg GAE g−1 and scavenging of 0.17 g, reaching a 42.87% yield. The extracts obtained by sCO2 + EtOH were characterized by high contents of essential fatty acids (linoleic acid and oleic acid) and bioactive compounds (gallic acid, trans-cinnamic acid, daidzein, and genistein). These extracts also showed a great potential for inhibiting hyaluronidase enzymes (i.e., anti-inflammatory activity). Thermogravimetric analyses of the samples showed similar profiles, with oil degradation values in the range from 145 to 540 °C, indicating progressive oil decomposition with a mass loss ranging from 93 to 98.7%. In summary, this study demonstrated the flexibility of scCO2 + EtOH as a green technology that can be used to obtain high-value-added products from fermented soybean.

Catalyst regulated interfacial synthesis of self-standing covalent organic framework membranes at room temperature for molecular separation

Covalent organic framework (COF) membranes have shown enormous potential for molecular separation due to their large surface areas and pre-designable structures. However, the mild and convenient preparation of COF membranes with high crystallinity has remained a significant challenge. In this work, we reported on a facile liquid–liquid interfacial polymerization method to fabricate self-standing imine-based COF membranes with excellent crystallinity and a tunable thickness at room temperature. Polymerization was confined at the immiscible organic solvent–water interface when the monomers in the dichloromethane met the catalyst aqueous solution. This unique design concept exploited the rapid formation of COF monolayers at the liquid–liquid interface to control catalyst diffusion and structural rearrangement, achieving high crystallinity of the COF membrane. Moreover, the thickness of the self-standing COF membranes could be regulated from 50 nm to 1 μm through the flexible regulation of the growth process. Benefiting from the large surface area of the COF membranes (378 m2/g) and the intensive π–π conjugate effect between the COFs and organic dyes, the obtained COF membranes exhibited high adsorption capacities toward Chrome Black T and Rose Bengal. This work may open a viable avenue to easily and mildly prepare COF membranes for water treatment.

How Subtle Changes Can Make a Difference: Reproducibility in Complex Supramolecular Systems.

The desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle "irregularities" on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry.

How Subtle Changes Can Make a Difference: Reproducibility in Complex Supramolecular Systems

AbstractThe desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle “irregularities” on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry.

Determination of water in organic solvents and raw food products by fluorescence quenching of a crystalline vinyl-functionalized COF.

Covalent organic frameworks (COFs) with good chemical stability, flexible chemical functionalization, tunable pore sizes, and high specific surface areas have been increasingly employed in the field of fluorescence sensing. In this work, a crystalline vinyl-functionalized COF TzDa-V was facilely prepared through a room-temperature synthetic method via condensation reaction between 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline (Tz) and 2,5-diallyloxyterephthalaldehyde (Da-V). The intermolecular charge transfer (ICT) effect endowed the TzDa-V with fluorescence characteristic, and it was sensitive to trace water and can be quenched due to the disruption of ICT process by water. On this base, the prepared COF TzDa-V with excellent chemical/thermal stability was applied to sensing of trace water in common organic solvents such as DMF, acetone, THF, and ethyl acetate with rapid response (less than 10s), satisfactory sensing range (0.5-18% water in DMF, 0.5-15% water in acetone, 0.5-16% water in THF, 0.5-5% in ethyl acetate, v/v), and high sensitivity. The limits of detection for water in DMF, acetone, THF, and ethyl acetate were 0.0497%, 0.0590%, 0.0502%, and 0.0766% (v/v), respectively. The proposed probe was successfully used for the detection of trace water in food products such as salt and sugar. The COF TzDa-V would be a good candidate for application in water sensing.

Copper Nanoclusters Loaded on SA/PVA Composite Films for Sensitive Detection of Trace Water in Organic Solvent

AbstractCopper nanoclusters (CuNCs), a new type of fluorescent material, have attracted extensive attention due to their excellent fluorescence properties and stability. In this paper, orange–red organic fluorescent CuNCs are prepared using reduced glutathione both as a template and reducing agent. CuNCs are then doped into a polymer matrix of alginate and polyvinyl alcohol using the aggregation‐induced emission enhancement effect to produce a kind of easy to use fluorescent composite films. The fluorescent composite films can realize the specific detection of trace water in the organic environment, and the detection limit can reach 0.0025% (volume ratio). Compared with the pure exposed CuNCs, the fluorescence intensity is greatly improved, and more importantly, the fluorescent composite films can be used repeatedly, saving resources and environmental protection.

Structural, Photophysical, and Water Sensing Properties of Pyrazolo[1,5‐a]pyrimidine‐Triphenylamine Hybrid Systems

AbstractThermal, structural, and photophysical properties of five pyrazolo[1,5‐a]pyrimidine‐triphenylamine hybrid systems substituted at position 3 of the fused ring were studied (probe/R: D1/H, D2/I, D3/CCSiMe3, D4/CHO, D5/CN). The solvatofluorochromism of D4 and D5 showed that the solvent dipolarity (SdP) is mainly responsible for their spectral changes, which arose from an internal charge transfer (ICT) from the triphenylamine (TPA) group to the acceptor substituent at position 3. As a result, D5 was applied for the detection of water in organic solvents (i. e., AcOEt and THF); this probe also exhibited an intense light emission in the solid‐state at 530 nm (ϕ=0.60). The five compound structures were solved and analyzed by X‐ray crystallography (XRC), with a link found between their structural characteristics and their physicochemical properties. For example, although all the probes exhibited good thermostabilities, this property decreased in D3 and was explained by frontier molecular orbital calculations based on the XRC results. Crystallographic studies were also used to interpret the differences in solid‐phase emission intensities in D1–D4 versus D5.