Pure THF Research Articles

Novel Anthracene and Carbazole Based Aggregation Induced Enhanced Emission Active Schiff Base as a Selective Sensor for Cu2+ ions.

In present work our group has synthesized two novel Schiff-bases, Di-Carbazole based Schiff-base (DB-1) and Di-Anthracene based Schiff-base (DB-2) using condensation reaction and characterized thorough different spectroscopic techniques such as mass spectrometry, IR spectroscopy, 1H and 13C NMR spectroscopy. Furthermore, the AIE(Aggregation induced emission) studies were done using water-THF mixture. As compared to pure THF, the DB-2 showed a 17.8-fold increase in fluorescence intensity with a bathochromic shift of 64nm in 80% water: THF mixture. For DB-1increase was seen at 70% water-THF combination. The analysis of the dynamic light scattering (DLS) further supported this excellent AIEE (Aggregation induced enhanced emission) characteristic. Furthermore, the spectrofluorometric techniques were used to examine the capacity of both Schiff bases to detect the heavy metals. It was discovered that only DB-1, with a detection limit of 2.4 × 10-8 M, was selective for the Cu2+ ion, whereas DB-2 had no sensing capability for metal ions. The Job's plot was used to determine the stoichiometry ratio of the DB-1 with Cu2+ to further examine the process. It was discovered that the ratio was 1:1 (DB-1:Cu2+). Additionally, the association constant of DB-1 for Cu2+ was 5.1 × 1011 M-1, demonstrating the excellent binding affinity of DB-1 for the Cu2+ ion.

The effect of water in THF/water mixtures on CMC, aggregation sizes, and fluorescence quenching of a new calix[4]resorcinarene macrocycle.

This study explores how water content modulates the self-assembly and fluorescence behavior of a novel calixarene, C1. C1 forms large, flattened structures in pure THF, but water addition triggers a transition to smaller, unimodal clusters. A critical micellar concentration (CMC) is identified, decreasing with increasing water content. Fluorescence quenching is observed upon water addition, attributed to nonradiative deactivation. These findings highlight water as a key regulator of C1's assembly and fluorescence, paving the way for further development of water-responsive calixarene systems.

Red-Emitting AIEE-Active Rhodamine-Based Ionic Liquid for the Ultrasensitive and Selective Detection of Mercury Ions.

A highly fluorescent, red-emitting rhodamine-based imidazolium ionic liquid (RhB-IL) was synthesized, and its structure was extensively verified using various spectroscopic techniques. The novel molecule showed exceptional selectivity toward Hg2+ ions over other competitive metal ions. Additionally, inspired by the solution results, a paper-based device was fabricated by embedding RhB-IL on paper strips and tested for the on-site detection of Hg2+ ions using a portable UV light source. Significantly, the device displayed excellent PL sensing behavior toward Hg2+ with a detection limit of 0.21 nM. In addition, RhB-IL showed the phenomena of aggregation-induced enhanced emission. In fact, when compared to the pure THF solution of RhB-IL, a remarkable 7.7-fold increase in PL intensity was seen for the 90% water fraction. Evidently, this is the first report of a paper-based Hg2+ detection system that uses a red fluorescent ionic liquid.

Paper-based device for nanomolar detection of Cd2+ using AIEE-active imidazolium ionic liquid functionalized phenothiazine based Schiff-Base

A highly green fluorescent phenothiazine-based imidazolium ionic liquid (IL) [PTZ-SB][Br] was synthesized and its structure was thoroughly elucidated by 1H, 13C NMR, FT-IR, UV–visible spectroscopy and Mass spectrometry. Furthermore, thermal resilience of the IL was established by TGA and DSC investigations. The novel molecule revealed a distinct recognition for Cd2+ ions over eleven other transition metal ions. Moreover, the promising results obtained in the solution phase interested us to embed [PTZ-SB][Br] on paper strips to create a paper-based fluorescent sensor, which was examined by a portable UV light source for the on-site Cd2+ detection. Interestingly, the device demonstrated exceptional fluorescence sensing behavior towards Cd2+ with a limit of detection (LOD) of 0.16 nM. Thus, the probe has noteworthy distinct and sensitive detection ability towards Cd2+, which might find practical and on-spot applications. Noticeably, [PTZ-SB][Br] demonstrated aggregation-induced enhanced emission (AIEE) phenomenon. In fact, an incredible 38.1-fold increase in fluorescence intensity was observed for 10:90 ratio of THF:water mixture as compared that for pure THF solution of [PTZ-SB][Br]. AIEE property was further supported by DLS studies. A paper-based device for Cd2+ sensing by applying an Ionic Liquid based Schiff base is reported herein for the first time.

Swelling Behavior of Lipophilic Polyelectrolyte Gels in Organic Solvents−Water or Sea Water Binary Mixtures

AbstractThe recovery of crude oil and volatile organic compounds (VOCs) spilt in the environment is an intractable problem for environmental scientists. In this paper, a new lipophilic polyelectrolyte gel as an absorbent for various volatile chemical compounds is demonstrated. It is prepared by radical copolymerization of an acrylate monomer with an ionic group, tetraalkylammonium tetraarylborate, octadecyl acrylate, and a crosslinker, dipropylene glycol diacrylate, in the presence of a radial initiator. Investigation of the swelling behavior for the mixtures of water or aqueous salts reveals that the gel shows similar swelling behavior to those for pure organic solvents. On the other hand, the swelling degree in THF‐water mixture is lower than that of pure THF, because THF and water are miscible to each other, and the presence of a small amount of water in THF reduces the compatibility of the gel and THF. The salting‐out effect can separate the THF‐water mixture to form a biphasic system and recover the high swelling ability of the gel. The swelling behavior in the mixture of water‐organic solvents systems provides a new insight for designing VOC and oil absorbents in various environmental conditions, especially in hydrosphere such as seas and lakes.

Solid-liquid equilibrium of ropivacaine in fourteen organic solvents: An experimental and molecular simulation study

The solubility of ropivacaine in fourteen pure solvents at 283.15 K to 323.15 K was determined via the gravimetric method and was well correlated with three thermodynamic models, including the Apelblat, λh, and NRTL models. Among all experimental solvents, the solubility of ropivacaine was found to be highest in pure THF and lowest in acetonitrile. In alcohol solvents, the maximum solubility was observed in amyl alcohol followed by 1-butanol, while the minimum value was observed in 1-propanol. The thermodynamic properties of mixing were calculated based on the NRTL equation, indicating that the mixing processes are spontaneous and entropy-driven. In addition, the crystal structure of ropivacaine was obtained and investigated by Hirshfeld surface analysis and molecular electrostatic potential surface analysis. The physicochemical properties of solvents, such as polarity, cohesive energy density and dielectric constant, were analyzed to explain the solid–liquid behavior of ropivacaine. Finally, a molecular dynamics simulation and radial distribution function analysis were performed. The results indicated that ropivacaine could interact with organic solvents via van der Waals interactions, electrostatic interactions, and hydrogen bonding.

A multi-stimuli-responsive tetraphenylethene derivative with high fluorescent emission in solid state

In this study, a tetraphenylethene derivative 2-(4-(4-(4,4,5,5-tetramethyl-1,3,2- dioxaborolan-2-yl)benzyloxy)phenyl)-3-(4-(1,2,2-triphenylvinyl)phenyl)acrylonitrile (abbreviated as TPEB) modified with borate ester group had been designed and synthesized, which exhibited high quantum yield in solid state (Φ = 0.66) and multi-stimuli-responsive performance. For the first one, TPEB showed aggregation induced emission (AIE) feature, the fluorescence intensity of which in water/THF mixture (fw = 90%) was 131.4 times that in pure THF. Secondly, TPEB can respond to viscosity and the fluorescence intensity increased by 43.8 times in high-viscosity solvent (1400 cP) from that in 2 cP. Thirdly, TPEB exhibited reversible mechanofluorochromic (MFC) character between blue (482 nm) and yellow-green- coloured (505 nm) fluorescence during grinding-fuming process. Moreover, TPEB can recognize hypochlorite (ClO−) under both UV–vis absorption and fluorescence emission modes with high selectivity. In the presence of ClO−, the UV–vis absorption band of TPEB red-shifted from 375 nm to 414 nm, which shifted from 501 m to 566 nm for fluorescence emission with 1.24 fold increase in intensity. The mechanism of multi-stimuli responsive performance was thoroughly studied through single crystal structure, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and hybrid density functional theory (HDFT) calculation.

Near-infrared-emitting difluoroboron β-diketonate dye with AIE characteristics for cellular imaging

Near-infrared (NIR) fluorophores have promoted the development of materials for bioimaging and therapy, but traditional NIR dyes usually suffer from aggregation-caused quenching (ACQ), impeding their applications. Herein, we propose a difluoroboron β-diketonate complex TTBE, consisting a donor-acceptor (D-A) structure with difluoroboron moiety as an electron acceptor and N, N-diethylaniline as well as triphenylamine (TPA)-thiophene building block as two electron donors. TTBE exhibited both solvatochromism and aggregation-induced emission (AIE) characteristics. In polar solvent DMSO, the emission maxima of TTBE were observed at 680 nm with low fluorescence quantum yield (ΦF = 0.01%), while in less polar solvent CH2Cl2, its emission maxima blue-shifted to 666 nm with increased fluorescence quantum yield (ΦF = 0.41%). The fluorescence of TTBE could be enhanced 650-fold in 90% hexane/THF mixture solution relatively to that in pure THF. Moreover, the fabricated F127/TTBE nanoparticles (NPs) showed NIR emission at 735 nm in water and excellent cytocompatibility even at high concentration (100 μg/mL). According to the results of cell imaging and flow cytometry, NPs were easily internalized into cells and distributed in the cytoplasm with strong red fluorescence. Therefore, this research inspires more insight into development of NIR AIE luminogens for biomedical imaging.

Aggregation-induced emissions in the mesogenic BF2 complexes of aroylhydrazines

PL peak intensity of 1a-BF2 (n = 12) versus fw of THF/H2O in pure THF (fw = 0) and THF/water with a specific fw. The concentration is 10 μM and PL emission was excited at 376 nm. Photos were taken under UV illumination.

Revealing the Growth of H2 + THF Binary Hydrate through Molecular Simulations

The use of H₂ as an ideal fuel is restricted by storage and transportation. It is proposed that THF is a promising promoter for storing H₂ in the form of hydrates under mild conditions. However, the molecular-level details of the formation of H₂ + THF binary hydrate are still unclear. In the present work, molecular simulations were conducted for two sets of temperature and pressure conditions to investigate the growth of H₂ + THF binary hydrate. We find that H₂ as a kinetic promoter can significantly accelerate the growth of a pure THF hydrate at 250 K and 50 MPa. Our results indicate that the evolution of the growth rate of H₂ + THF binary hydrate with temperature and pressure is similar to that of the pure THF hydrate, where the growth rate is the maximum at 260 K and a fixed pressure of 50 MPa; pressure has a negligible impact on the growth rate of the binary hydrate at pressures of 10–110 MPa and a fixed temperature of 250 K. This means that THF molecules control the growth process of H₂ + THF binary hydrate at our conditions except that the rearrangement of water molecules dominates the growth process at 230 K and 50 MPa. Increasing temperature and pressure can lower the percentage of empty cages in the newly formed binary hydrate, thus improving the occupancy of 5¹² cages by H₂. The occupancy rate of 5¹²6⁴ by H₂ at different temperatures is correlated with the growth rate of the binary hydrate. As a result, H₂ storage capacity is associated with the trend of the growth rate. Moreover, increasing pressure will increase the average number of H₂ molecules in each 5¹²6⁴ cage, and triple H₂ clusters begin to fill 5¹²6⁴ at 110 MPa and 250 K, which dramatically enhances the H₂ storage capacity in the binary hydrate.

An AIE‐Active Tetraphenylethylene‐Based Cyclic Urea as a Selective and Efficient Optical and Colorimetric Chemosensor for Fluoride Ions

AbstractAnion sensing is a very challenging and important issue in many diverse fields, including biological, medical and environmental sciences. In this paper, we report the serendipitous synthesis of a tetraphenylethylene (TPE) bearing a cyclic urea (coded as: 1). This easy‐to‐make, simple chemosensor shows high selectivity towards fluoride (F−) ions. Importantly, this work demonstrates two important factors: firstly, the use of cyclic urea for ion sensing and secondly, the use of aggregation induced emission (AIE)‐ TPE signalling units. This selective fluoride sensing can be observed by the naked eye, UV‐vis absorption, fluorescence spectroscopy, and 1H‐NMR spectroscopy. Solutions of sensor 1 are fluorescent in DMSO with fluorescence quantum yield Φ=1.3 and upon addition of fluoride ions the emission is quenched with ΦF=0.07. Notably, other anions, such as CN−, AcO−, NO3−, H2PO4−, HSO4−, I−, OH−, ClO4−, SCN− and Cl−, do not show any quenching effect. The binding constant (K) between sensor 1 and fluoride was found to be 4.90×108 M−2 with a detection limit of 30 μM. We also studied AIE‐activity of 1 in THF/water mixture. As such the fluorescence quantum yield (ΦF) of 1 in pure THF solution shown to be 0.05 % which was enhanced 22‐fold to 1.98 and 6.65 % at fw=90 and 99 %, respectively. This is clear confirmation that compound 1 is AIE active due to decreased solubility and increased molecular self‐assembly as the water fraction is increased.

Switching of Self-Assembly to Solvent-Assisted Assembly of Molecular Motor: Unveiling the Mechanisms of Dynamic Control on Solvent Exchange.

Natural biological molecular motors are capable of performing several biological functions, such as fuel production, mobility, transport, and many other dynamic features. Inspired by these biological motors, scientists effectively synthesized artificial molecular motors to mimic several biological functionalities. Several molecular systems, from sensitive materials to molecular motors, are essential for controlling dynamic processes in larger assemblies. In this work, we discuss the self-assembly of molecular motors in water and how this self-assembly switches to the solvent-assisted assembly as solvent changes to a water-THF (tetrahydrofuran) mixture. We present an elaborate description of the morphological changes of molecular motor assemblies from pure water to a water-THF mixture to pure THF. Under the influence of THF solvent, molecular motors form an assembled structure by taking a sufficient number of THF molecules in between themselves, resulting in an assembled molecular motor with a softened core. So, molecular motor assembly swells in the water-THF mixture, and in pure water, it shrinks. This solvent-assisted assembled structure has a specific shape. We have confirmed this assembly as a solvent-assisted assembly with the help of molecular dynamics simulation and quantum chemical analysis. Molecular motor-THF and THF-THF interactions are the main responsible interactions for solvent-assisted assembly over self-assembly. This work is a perfect example of conversion between self-assembly (shrinking) and solvent-assisted assembly (swelling) of molecular motors by adding THF into water or vice versa. A spectacular check on the shrinking and swelling by merely altering solvents illustrates so many intriguing possibilities for an alteration of dynamic processes at the nanoscale.

High Yield Organic Superconductors via Solution-Phase Alkali Metal Doping at Room Temperature.

Alkali metal doping is an essential process for developing organic superconductors. The conventional vapor-phase alkali metal doping, however, frequently suffers from low efficiency and poor reproducibility mainly due to the inhomogeneous reaction between alkali metal vapor and target organic molecule powder. To overcome this issue, here we developed a facile and highly reproducible solution-phase alkali metal doping (SPD) and successfully applied it to prepare potassium-doped fullerene (K3C60) superconductors. Different from the conventional vapor-phase alkali metal doping, the SPD method resulted in almost perfect diamagnetism with an unprecedented high shielding fraction (∼99.5%) with high reproducibility (>80%). It works well with popular commercially available solvents, like ammonia solution in THF, methylamine solution in THF, and even pure THF at room temperature. We believe that our highly facile and efficient SPD approach will be a great help for the finding of next-generation organic superconductors, especially searching for high-Tc organic superconductors.

A Fluorescent Chemosensor with a Hybridized Local and Charge Transfer Nature and Aggregation‐Induced Emission Effect for the Detection of Picric Acid

AbstractA novel fluorescent molecule TPA‐CO, which exhibited a hybridized local and charge transfer (HLCT) nature and aggregation‐induced emission (AIE) effect, was developed and utilized as a chemosensor for the detection of picric acid (PA) in both organic solution and water. It was found that TPA‐CO exhibited apparent fluorescent quenching along with the color change to yellow upon the addition of PA. Notably, more sensitive detection was achieved in the H2O: THF (9:1) medium, with the LOD almost two third lower than that in pure THF. Such more sensitive response in aqueous solution was accomplished by the synergy of HLCT and AIE effects in TPA‐CO nanoparticles, which facilitated both highly efficient fluorescence in the absence of PA and rapid quenching rate in the presence of PA, respectively. Therefore, it is proposed an effective design strategy by integrating HLCT and AIE effects for developing PA chemosensors.

Aggregation-induced emission organogel formed by both sonication and thermal processing based on tetraphenylethylene and cholesterol derivative

In this work, we designed and synthesized a novel asymmetric tetraphenylethylene-based fluorescence compound, which can form cholesteryl liquid crystal by cooling from the isotropic melt and exhibit typical AIE property with a 180-fold enhancement of fluorescence intensity in 90% water fraction of THF/water mixture than pure THF. This compound can gelate in cyclohexane via both ultrasound stimuli and general sol–gel processes accompanied by remarkable enhanced fluorescence emission. The self-assembly and gelling properties can be controlled by ultrasound stimuli and renewed by a thermodynamic process. The mechanism of the process was investigated by UV–Vis absorption, PL emission, scanning electron microscopy, wide-angle X-ray scattering analysis, and small-angle X-ray scattering analysis. The results reveal that the cooperation and relative competition of multiple intermolecular interactions, which are the main contributors for the formation of gel influenced by the sonication or thermal stimulus.

Purification of tetrahydrofuran from its aqueous azeotrope by extractive distillation: Validation of model and simulation

ABSTRACTTetrahydrofuran (THF) purification by distillation is difficult due to the existence of its homogeneous, minimum boiling azeotrope with water. Previously conducted extractive distillation runs were used in this work to validate a rigorous model.The validated model was then used to arrive at a feasible range of operating parameters by performing sensitivity analysis. It is shown through simulations that with the correct operating parameters, use of dimethyl sulfoxide can help obtain almost pure THF.

Aggregation induced emission properties of new cyanopyridone derivatives

Nowadays, fluorescent organic compounds have attracted much research interest due to their academic significance and applications. The present article deals with the fluorescence behaviors of conjugated cyanopyridone based compounds (CP1–5) possessing various donor/acceptor moieties. These compounds showed aggregation-induced emission (AIE) properties in their THF/H2O mixtures due to the restriction of intramolecular rotation and exhibited a blue emission behavior in their aggregated state. During the AIE study, compound (CP-1) showed a red shift in the emission profile and rest of the compounds exhibited a blue shift in their emission profile. Further, field emission scanning electron microscope (FESEM) and Epi-fluorescence microscopic studies showed that the stronger emission of these compounds is mainly due to the formation of large-sized aggregates in the THF/water mixture than the pure THF.

Reversible ratiometric silver ion and pH probe constructed from a quinoline-containing diphenylsulfone derivative with AIEE effect

A novel organic fluorophore, di-4-(2-quinolinylhydrazinyl)diphenyl sulfone (QDPS), was designed and synthesized by hydrazino bridging of quinoline and diphenylsulfone. The fluorophore emits weak blue fluorescence in pure THF and becomes a strong emitter in aggregated state, signifying the aggregation-induced emission enhancement (AIEE) effect. It can selectively bind Ag-ion on an extremely low concentration (LOD = 2.0 × 10−7 mol/L) with 1:2 binding mode and a binding constant of 1.58 × 1010 (mol/L)−2 in the mixture solution of THF/water (V/V = 1/9) as the reversible ratiometric UV and fluorescence chemosensors. After protonation by adding acids, QDPS has an unexpected tunable AIEE effect from blue in pure DMF to green in the aggregated state. Additionally, its emission can be reversibly switched between blue and green by reiterant deprotonation and protonation. This unique ability enables QDPS as a novel reversible ratiometric pH probe, as well as a colorimetric sensor for detecting acidic and basic organic vapors.

Interfacial Properties of Tetrahydrofuran and Carbon Dioxide Mixture from Computer Simulation

We determined the interfacial properties of the tetrahydrofuran + carbon dioxide (THF + CO2) binary mixture from direct simulation of the vapor–liquid interface. We consider two different models of THF based on the transferable parameters for phase equilibria-united atom (TraPPE-UA) version approach. In the first case, we use the original (flexible) TraPPE-UA model force field for the ether [J. Phys. Chem. B 2012, 115, 11234]. The second model is a planar, rigid, and approximated TraPPE-UA model recently proposed by us [J. Chem. Phys. 2016, 144, 144702]. It is demonstrated that the sophisticated flexible model does not have an overall advantage in comparison with the simplified planar model. Indeed, both models are able to predict the phase behavior and interfacial tension of pure THF with high accuracy in a wide range of temperatures and pressures. It is noticed that the planar model is faster for simulation because the internal degrees of freedom are frozen (neither bending nor torsional intramolecular ...

D-π-A type barbituric derivatives: Aggregation induced emission, mechanofluorochromic and solvatochromic properties

Four new barbituric derivatives that bears the furan and thiophene and the 1,3-dimethyl barbituric acid moiety, has been synthesized. These D-π-A type conjugated compounds showed obvious intramolecular charge transfer (ICT) properties, which were evidenced by theoretical calculations and spectral analysis. The compounds exhibited Aggregation induced emission (AIE) characteristic. TOB-1 and FTB-1 were quite weakly emission in pure THF, while a significant AIE effect was observed in water/THF (fw = 70% and 90%) mixtures with a large AIE factor of 40.5 and 46.8. Barbituric acid derivatives with thiophene electron donating group possess the distinct mechanofluorochromic (MFC) behavior. The original powder of FTB-1, BFTB-2 and TFTB-4 could emit strong orange-yellow (614 nm), orange-red (663 nm) and yellow (571 nm) light under UV irradiation, while the fluorescence color changed into orange (629 nm), red (691 nm) and orange yellow (583 nm) emission after grinding, respectively, a red shift of 15, 28 and 12 nm was observed, respectively. Among them, the emission color of compound BFTB-2 can be observed by naked eyes. Such mechanochromism was reversible upon the treatment of grinding and fuming with CH2Cl2. The XRD studies of the powders showed that the MFC behavior of FTB-1 and BFTB-2 might be switched reversibly under the stimulus of external force because of the decrease in crystallinity. The resultant red shift of TFTB-4 was attributed to the planarization induced by grinding.