Tetrahydrofuran-water Mixture Research Articles

Coordination Structure of Samarium Diiodide in a Tetrahydrofuran-Water Mixture.

Chemoselective reductive conversion of organic and inorganic compounds has been developed by the combination of samarium(II) diiodide (SmI2) and water. Despite the extensive previous studies to elucidate the role of water in the reactivity of SmI2, the direct structural data of the reactive Sm2+-water complexes, SmI2(H2O)n, in an organic solvent-water mixture have not been reported experimentally so far. Herein, we performed the structure analysis of the Sm2+-water complex in tetrahydrofuran (THF) in the presence of water by in situ X-ray absorption spectroscopy using high-energy X-rays (Sm K-edge, 46.8 keV). The analysis revealed the dissociation of the Sm2+-I bonds in the presence of ≥ eight equivalents of water in the THF-water mixture. The origin of the peak shift in the UV/visible absorption spectra after the addition of water into SmI2/THF solution was proposed based on electron transitions simulated with time-dependent density-functional-theory calculations using optimized structures in THF or water. The obtained structural information provides the fundamental insights for elucidating the reactivity and chemoselectivity in the Sm2+-water complex system.

Phenoxazine-Quinoline Conjugates: Impact of Halogenation on Charge Transfer Triplet Energy Harvesting via Aggregate Induced Phosphorescence.

Room-temperature phosphorescence (RTP) from organic compounds has attracted increasing attention in the field of data security, sensing, and bioimaging. However, realization of RTP with an aggregate induced phosphorescence (AIP) feature via harvesting supersensitive excited charge transfer triplet (3CT) energy under visible light excitation (VLE) in single-component organic systems at ambient conditions remains unfulfilled. Organic donor–acceptor (D–A) based orthogonal structures can therefore be used to harvest the energy of the 3CT state at ambient conditions under VLE. Here we report three phenoxazine–quinoline conjugates (PQ, PQCl, PQBr), in which D and A parts are held in orthogonal orientation around the C–N single bond; PQCl and PQBr are substituted with halogens (Cl, Br) while PQ has no halogen atom. Spectroscopic studies and quantum chemistry calculations combining reference compounds (Phx, QPP) reveal that all the compounds in film at ambient conditions show fluorescence and green-RTP due to (i) radiative decay of both singlet charge transfer (1CT) and triplet CT (3CT) states under VLE, (ii) energetic nondegeneracy of 1CT and 3CT states (1CT– 3CT, 0.17–0.21 eV), and (iii) spatial separation of highest and lowest unoccupied molecular orbitals. Further, we found in a tetrahydrofuran–water mixture (fw = 90%, v/v) that both PQCl (10–5 M) and PQBr (10–5 M) show concentration-dependent AIP with phosphorescence quantum yields (ϕP) of ∼25% and ∼28%, respectively, whereas aggregate induced quenching (ACQ) was observed in PQ. The phosphorescence lifetimes (τP) of the PQCl and PQBr aggregates were shown to be ∼22–62 μs and ∼22–59 μs, respectively. The ϕP of the powder samples is found to be 0.03% (PQ), 15.6% (PQCl), and 13.0% (PQBr), which are significantly lower than that of the aggregates (10–5 M, fw = 90%, v/v). Film (Zeonex, 0.1 wt %) studies revealed that ϕP of PQ (7.1%) is relatively high, while PQCl and PQBr exhibit relatively low ϕP values (PQCl, 9.7%; PQBr, 8.8%), as compared with that of powder samples. In addition, we found in single-crystal X-ray analysis that multiple noncovalent interactions along with halogen···halogen (Cl···Cl) interactions between the neighboring molecules play an important role to stabilize the 3CT caused by increased rigidity of the molecular backbone. This design principle reveals a method to understand nondegeneracy of 1CT and 3CT states, and RTP with a concentration-dependent AIP effect using halogen substituted twisted donor–acceptor conjugates.

Indolo[3,2-b]carbazole derivatives with high fluorescent emission both in solution and aggregated states and mechanical-induced emission enhancement characteristic

Four novel indolo[3,2-b]carbazole derivatives (F-ICZ, 2F-ICZ, F-ICZ-Ben and 2F-ICZ-Ben) with A-π-D-π-A structure were designed and synthesized via Knoevenagel and Suzuki-Miyaura reactions. The photophysical properties of indolo[3,2-b]carbazole derivatives in different solvents, aggregates emission behaviors and solid state were investigated systematically. The compounds exhibited an obvious solvatochromic effect. Compounds F-ICZ and 2F-ICZ showed AIEE property in tetrahydrofuran-water mixture solution, and compounds F-ICZ-Ben and 2F-ICZ-Ben exhibited high fluorescent emission both in solution and aggregated states. The significant reasons may be the increase of conjugate degree in solution and no obviously π-π stacking in aggregated state. Furthermore, compound F-ICZ possessed mechanofluorochromic property, and F-ICZ-Ben exhibited mechanical-induced emission enhancement characteristics. The reasons for mechanofluorochromic property are the changes in molecular packing patterns. This work further provided an efficient strategy for designing more mechanofluorochromic materials with high fluorescent emission both in solution and aggregated states.

Comparison of the exergetic performance and CO2 emissions of tetrahydrofuran-water separation processes

There are different purification technologies aimed at separating azeotropic mixtures, among which extractive and pressure-swing distillation stand out. While the former is characterized by the use of a solvent, the latter is employed when the composition of mixtures is significantly affected by the operating pressure. In this article, said separation technologies are applied to a tetrahydrofuran-water mixture and further compared to one another in terms of their exergetic performance and CO2 emission rate. Two configurations were used as case studies and further improved in order to propose new fully-integrated designs. The exergy analysis was performed by determining both the total exergy destruction rate and exergetic efficiency, whereas the CO2 emissions were evaluated by estimating the indirect releases due to electricity and thermal energy consumption. Although the results showed that the proposed schemes have a higher exergetic performance and lower CO2 emission rate than their original designs, the extractive processes proved to be better than both pressure-swing technologies. More specifically, the proposed fully heat-integrated extractive configuration was deemed to be the best alternative since it has approximately 7.4 % lower exergy destruction rate and 7.2 % lower carbon emission rate than the fully heat-integrated pressure-swing scheme.

Aggregation-Induced Emission and White Luminescence from a Combination of π-Conjugated Donor-Acceptor Organic Luminogens.

Two new star-shaped phenyl- and triazine-core based donor–acceptor (D–A) type conjugated molecules bearing triphenylamine end-capped arms were synthesized and characterized as imminent organic optoelectronic materials. Photophysical properties of the compounds were explored systematically via spectroscopic and theoretical methods. Because of the presence of donor–acceptor interactions, these luminogens display multifunctional properties, for instance, high extinction coefficient, large stokes shift, and pronounced solvatochromic effect. The compounds also exhibited phenomenon known as aggregation-induced emission on formation of nano-aggregates in the tetrahydrofuran–water mixture. The aggregate formation was confirmed by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering analyses. Moreover, by controlling the electron withdrawing ability of the acceptor, complementary emissive fluorophores (blue and yellow) were achieved. These two complementary colors together span the entire range of visible spectrum (400–800 nm) and therefore when mixed in a requisite proportion generate white light in solution phase. These findings have potential for the progress of new organic white light radiating materials for applications in lighting and display devices.

Pervaporation separation of an azeotropic mixture of a tetrahydrofuran–water system with nanostructured polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol)

ABSTRACTCage ‐ structured polyhedral oligomeric silsesquioxane (POSS) molecules were used as modifiers in the fabrication of poly(vinyl alcohol) (PVA) membrane for the separation of an azeotropic mixture of tetrahydrofuran (THF) and water system. Poly(ethylene glycol) and anionic octa(tetramethyl ammonium)‐functionalized POSS were used for this study. The membranes exhibited excellent water selectivity and permeance because of their preferential interactions toward water molecules in the azeotropic THF–water mixture. In the presence of poly(ethylene glycol)–POSS and anionic octa(tetramethyl ammonium)–POSS, the PVA membrane exhibited a significant increase in selectivity. A modified Maxwell–Stefan equation was used for the computation of the theoretical flux, which was compared with the experimental values. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47060.

Biluminescence via Fluorescence and Persistent Phosphorescence in Amorphous Organic Donor(D4)-Acceptor(A) Conjugates and Application in Data Security Protection.

Purely organic biluminescent materials are of great interest due to the involvement of both singlet and long-lived triplet emissions, which have been rarely reported in bioimaging and organic light-emitting diodes. We show two molecules 3,4,5,6-tetraphenyloxy-phthalonitrile (POP) and 3,4,5,6-tetrakis- p-tolyloxy-phthalonitrile (TOP), in which POP was found to exhibit fluorescence and persistent room-temperature green phosphorescence (pRTGP) in the amorphous powder and crystal states. Both POP and TOP show aggregation-induced emission in a tetrahydrofuran-water mixture. We found in single-crystal X-ray analysis that intra- and intermolecular lp(O)···π interactions along with π(C = C)···π(C≡N), hydrogen bond (H-B), and C-H···π interactions induce a head-to-tail slipped-stack arrangement inPOP. In addition, the X-ray structure of TOP with a slipped-stack arrangement induced by only π(C═C)···π(C≡N) and H-B interactions shows dim afterglow only in crystals. These indicate that more noncovalent interactions found inPOP may reinforce relatively efficient intersystem crossing that leads to pRTGP. Given the unique green afterglow feature in amorphous powder of POP, document security protection application is achievable.

Comparison of extractive and pressure-swing distillation for separation of tetrahydrofuran-water mixture

Tetrahydrofuran (THF) is widely used in many processes as solvent or chemical intermediate. It is necessary to separate mixture of THF-water, because in most commercial production processes, THF is produced from its water mixture. However, the above mixture cannot be separated with ordinary distillation, since THF and water can form azeotrope. Instead, extractive distillation (ED) and pressure-swing distillation (PSD) have been widely applied for commercial separation of mixture of THF-water. In this paper, Aspen Plus simulator is used to simulate extractive distillation and pressure-swing distillation process for separation of mixture of THF-water. Economic analysis is carried out by Aspen Process Economic Analyzer (APEA) for the two processes. The conclusion obtained based on the above process simulation and analysis is that the total annualized cost of the extractive distillation is slightly lower than that of pressure-swing distillation. The results obtained provide useful references for commercial separation of mixture of THF and water.

Designing Durable Vapor‐Deposited Surfaces for Reduced Hydrate Adhesion

The formation and accumulation of clathrate hydrates inside oil and gas pipelines cause severe problems in deep‐sea oil/gas operations. In the present work, durable and mechanically robust bilayer poly‐divinyl benzene/poly(perfluorodecylacrylate) coatings are developed using initiated chemical vapor deposition (iCVD) to reduce the adhesion strength of hydrates to underlying substrates (silicon and steel). Tetrahydrofuran (THF) dissolved in water with a wt% concentration of 0–70 is used to study the formation of hydrates and their adhesion strength. Goniometric measurements of the THF–water droplets on the substrates exhibit a reduction in advancing and receding contact angles with an increase in the THF concentration. The strength of hydrate adhesion experiences a tenfold reduction when substrates are coated with these iCVD polymers: from 1050 ± 250 kPa on bare silicon to 128 ± 100 kPa on coated silicon and from 1130 ± 185 kPa on bare steel to 153 ± 86 kPa on coated steel. The impact of subcooling temperature and time on the adhesion strength of hydrate on substrates is also studied. The results of this work suggest that the THF–water mixture repellency of a given substrate can be utilized to assess its hydrate‐phobic behavior; hence, it opens a pathway for studying hydrate‐phobicity.

Fabrication of a microvesicles-incorporated fibrous membrane for controlled delivery applications in tissue engineering

A scaffold, which can provide mechanical support for tissue regeneration and simultaneously release functionally active biomolecules are highly desirable for tissue engineering applications. Herein, we report the fabrication of a fibrous mesh of polycaprolactone (PCL) incorporating PCL-pluronic (F127) microvesicles through electrospinning, by exploiting the slow dissolution of PCL in glacial acetic acid (g-AA). Micro-vesicles 1–10 μm in diameter were fabricated through a non-solubility driven spontaneous self-assembly and stabilization of F127 with low molecular weight PCL in tetrahydrofuran-water mixture. Time-dependent stability of the vesicles in g-AA was confirmed prior to the electrospinning. The electrospun membrane was found to be comprised of microvesicles entangled in a fibrous mesh of PCL with a fiber diameter ranging from 50–300 nm. Significant reduction in the release rate of rhodamine-B, an indicator dye from the electrospun membrane, when compared to that from the vesicle alone, evidences the surface coating of the vesicles with high molecular weight PCL during electrospinning. The vesicle incorporated membrane exhibited increased hydrophilicity when compared to the control PCL membrane, possibly due to surface unevenness and the hydrophilic F127. This enhanced surface hydrophilicity led to an increased cell viability of L929 cells on the membrane.

The modeling of hydrate growth kinetics in tetrahydrofuran–water mixture based on subcooling driving force

The objective of this work is the investigation of tetrahydrofuran hydrate formation under atmospheric pressure in a static reactor without stirring. The growth rate of hydrate is mostly controlled by the conduction heat transfer phenomenon. An approximate method based on the improved quasi solution was utilized to estimate the interface position of THF hydrate layer around a planar probe. In said method, the polynomial (order 2) and exponential assumptions were introduced as temperature profile for solid and liquid phases in finite regions. A proper agreement was found between the results of mentioned solution and experimental data with average deviation about 3.5%. Also the parametric curves were presented to describe the effect of operating parameters on the interface motion between hydrate and liquid phases. The hydrate formation based on subcooling driving force is very effective to solve the separation difficulty between hydrate crystals and solution in water desalination procedure.

PPI–SA and PAMAM–SA dendrimers assisted synthesis of silver nanoparticles: structure, optical properties and stability

"Poly(propylene-imine) (PPI) and poly(amidoamine) (PAMAM) dendrimers of different generations functionalized with 4-(4′-pentoxybenzoyloxy)salicylaldehyde (SA) promesogenic units were applied for the synthesis of silver (Ag) nanoparticles in tetrahydrofuran–water mixture solution. Influence of the dendrimer type and their generations on formation and stability of nanoparticles were studied. Structural and optical properties of Ag nanoparticles, and their modifications with aging were characterized by means of transmission electron microscopy, UV–vis absorption and Fourier transform infrared spectroscopy. Experimental investigations showed that immediately after the synthesis the particles were of spherical shapes with slightly different sizes depending on the used dendrimer type, but independent of their generation. The dendrimer type strongly influenced particle modifications during the aging: particles protected with PPI–SA dendrimers undergone significant alterations in time both in their sizes and shapes, while the particles remained almost unchanged when PAMAM–SA dendrimers were used for their protection. We, therefore, presume that morphological differences of aged nanoparticles are mainly determined by different chemical structures of dendrimer cores rather than by their terminal groups; additional carbonyl groups in PAMAM–SA dendrimer core units play an important role in stabilizing Ag nanoparticles.

Large-Scale Structures in Tetrahydrofuran–Water Mixture with a Trace Amount of Antioxidant Butylhydroxytoluene (BHT)

Author: Because of the closed-loop phase diagram of tetrahydrofuran (THF)-water mixture, THF aqueous solution naturally exhibits concentration fluctuations near the phase boundary. Besides the fast mode induced by concentration fluctuations, the 4.5% mole fraction THF aqueous solution is also characterized by a slow mode. The existence of a trace amount of butylhydroxytoluene (BHT) antioxidant in commercial THF strongly influences the slow mode in 4.5% mole fraction THF aqueous solution. A core-shell structure with a BHT core and a shell made from THF-rich THF-D(2)O mixture was identified by the combination of dynamic laser light scattering (DLS) and small-angle neutron scattering (SANS). BHT is hydrophobic, stabilized by a THF-rich domain in THF aqueous solution and acts as a tracer to make the large-scale structure (slow mode) "visible" through SANS because of its larger contrast with the solvent. In contrast, this large-scale structure was almost not detectable by SANS when BHT was removed from the THF-D(2)O mixture. Combined UV-vis, DLS, and static light scattering (SLS) indicated that slow-moving objects do exist and that their sizes almost do not change, but their concentration decreases to a small but nonzero value at the infinite dilution limit. The origin of the elusive large-scale structure at zero BHT concentration is still not clear, but it might be associated with some hydrophobic impurities or nanobubbles. However, a polydisperse sphere model of ∼8.5% mole fraction THF-D(2)O mixture can fit the structure with a radius of ∼100 nm, which gives the temperature-dependent low-q SANS profiles of 4.5% mole fraction THF aqueous solution at zero BHT concentration.

Imidazole-bearing tetraphenylethylene: fluorescent probe for metal ions based on AIE feature

With an aggregation-induced emission feature, a suspension of imidazole-bearing tetraphenylethylene in a tetrahydrofuran–water mixture with a high water fraction is highly emissive, and can be completely quenched by Fe3+ ions due to the coordination between imidazole moieties and the Fe3+ ion.

Adsorption of Ionic Liquid onto Halloysite Nanotubes: Mechanism and Reinforcement of the Modified Clay to Rubber

An ionic liquid (IL), 1-butyl-3-methyl-imiazolium hexafluorophosphate [BMIm]PF6, was coated onto halloysite nanotubes (HNTs) in tetrahydrofuran–water mixture. The IL layers on the HNTs were confirmed by thermogravimetric analysis, diffuse reflectance infrared Fourier transform spectroscopy, determination of contact angle, and porosity analysis. The interaction between IL and HNTs, proposed to be hydrogen bonding, was verified by various spectral results such as Raman spectroscopy, nuclear magnetic resonance and X-ray photoelectron spectroscopy. Because of their interaction, the crystallization behavior of IL in the presence of HNTs was found to be changed, as indicated by the results of differential scanning calorimetry. The IL-coated HNTs (m-HNTs) were used as reinforcement for styrene–butadiene rubber. Compared with the compounds with uncoated HNTs, the uncured compounds with m-HNTs showed faster curing, and the resulting vulcanizates showed substantially higher tensile strength and much lower hardness. The unique changes in the compounds are correlated to the changes in filler dispersion and interaction between IL and HNTs.

Origin of cononsolvency, based on the structure of tetrahydrofuran-water mixture

The origin of poly(N-isopropylacrylamide) (PNIPAM) cononsolvency in tetrahydrofuran-water (THF-water) mixture was studied from the point of view of mixed solvent structure. The dynamic equilibrium of THF-water composition fluctuation in the mixed solvent system was found to be the main variable for this cononsolvency effect. Temperature and THF content dependences of composition fluctuation were studied by a combination of small angle neutron scattering (SANS), dynamic laser light scattering, and viscometry. A lower critical solution temperature (LCST) type phase diagram for THF-water mixture was established by SANS. The composition fluctuation in THF-water system reaches the maximum at about 20 mol % THF content at constant temperature and increases with temperature as getting closer to the phase boundary. This kind of composition fluctuation induces PNIPAM cononsolvency. When the THF content is lower than 4.5 mol %, the composition fluctuation influence of the THF-water structure is quite weak and most of water structure is not disturbed. Then, at low THF content, poly(N-isopropylacrylamide-co-ethylene glycol) (PNIPAM-co-PEG) microgel can still form hydrogen bonds with water and exist in the swollen state. The basic phase transition behavior of the microgel in THF-water is relatively similar to that in pure water, except for the shift of LCST to lower temperature. With THF content increasing to 20 mol %, the influence of composition fluctuation in the THF-water mixture becomes dominant. Solvent-solvent interaction is stronger than mixed solvent-polymer interaction. So PNIPAM does not dissolve in the mixed solvent, and the microgel is in the collapsed state. Further increase in THF content abates the contribution of composition fluctuation, and the structures of mixed solvents tend to be that in pure THF. PNIPAM becomes soluble again via Van der Waals interaction between THF and polymer.

Separation of Tetrahydrofuran–Water Azeotropic Mixture by Batch Extractive Distillation Process

Tetrahydrofuran and water formed a minimum azeotrope at 64°C, which contains water 6.7% in mass fraction. We could not use conventional distillation to separate these two components. In this work, a systematic study of the separation of the tetrahydrofuran–water mixture with a new en trainer by batch extractive distillation was performed. Based upon the lots of computation, 1,2-propanediol was chosen to be the entrainer. It broke the original binary azeotrope. The process feasibility analysis was validated by rigorous simulation with chemical process simulation software—HYSYS. Plant 2.2 and DISTIL 4.1. Simulation results were then corroborated in a batch experimental packing column with the selected entrainer. The experimental and simulation results agreed well.

One‐pot synthesis of a few nanocomposites with poly(N‐vinylcarbazole) and CdS, Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles with γ irradiation

AbstractThe one‐pot synthesis of nanocomposites of a conductive poly(N‐vinylcarbazole) (PVK) with CdS, Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles was performed with γ irradiation in a tetrahydrofuran–water mixture (3/1 vol %). For comparison, the CdS, Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles were also prepared with γ irradiation with polyvinylpyrrolidone as a stabilizer. Ultraviolet–visible spectroscopy, transmission electron microscopy, X‐ray diffraction analysis, and photoluminescence spectroscopy were used for the characterization of CdS, Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles and nanocomposites of PVK with CdS, Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles. The absorption spectrum of the CdS‐nanoparticle‐based composite revealed a quantum confinement effect. The emission spectrum of the composite with CdS nanoparticles and PVK indicated the block effect of PVK for surface recombination. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1809–1815, 2006

Formation and dissociation of clathrate hydrate in stoichiometric tetrahydrofuran–water mixture subjected to one-dimensional cooling or heating

Formation and growth, or melting, of a polycrystalline layer of tetrahydrofuran (THF) hydrate from, or into, a liquid solution having the same composition as that of the hydrate have been observed in a macroscopically one-dimensional heat-transfer system under atmospheric pressure. Experiments were performed with either the liquid THF–water solution or the THF hydrate initially filling a 260 cm 3 cell which was sealed top and bottom by temperature-controlled copper plates and by glass plates on the side. In one group of experiments, the cell filled with the solution was initially adjusted at the hydrate–solution equilibrium temperature, T eq(4.4°C). The top copper plate was then cooled quasi-stepwise, while the temperature at the bottom copper plate was either unchanged or increased quasi-stepwise, resulting in the growth of a planar polycrystalline hydrate layer down from the surface of the top plate. In another group of experiments, the cell was initially filled with a polycrystalline THF-hydrate phase at a temperature slightly lower than T eq. Successively, the temperature at the bottom plate was increased quasi-stepwise to exceed T eq, resulting in the melting of the hydrate phase from the bottom. The behavior of such growth and melting of the hydrate layers observed in the experiments is in general agreement with that predicted by relevant theoretical/numerical analyses of transient conductive and/or free-convective heat transfer from/to the hydrate–solution interface, where the temperature is assumed to be fixed at T eq. Also described in this paper is an unexpected finding in a particular experimental condition—the formation of column-like hydrate crystals extending almost across the 20-mm spacing between the top and bottom plates, which precedes the growth of a planar polycrystalline layer.

Autoprotolysis Constants and Standardization of pH Measurements in Tetrahydrofuran-Water Mixtures

Standard emf for the cell Pt/Ag/AgCl/HCl in THF-water/GE (glass electrode) in tetrahydrofuran-water mixtures containing 0–70% (w/w) of tetrahydrofuran and values of the autoprotolysis constants, Kap, of these media were obtained. The influence of variations in the solvent composition on pKap values was evaluated. The resulting equations enables us to determine pKap values in any tetrahydrofuran-water mixture, and thus permit one to establish the pH scale in these mixtures. The quasilattice quasichemical (QLQC) theory of preferential solvation was applied to obtain the degree of preferential solvation of hydrogen ions in these media, in order to explain the variation of the pKap values obtained in the tetrahydrofuran-water mixtures studied.