Tetrahydrofuran Solvent Research Articles

Effects of different solvents on ultraviolet absorption and fluorescence intensity of 2,4-dichlorophenol, 2,4,6-trichlorophenol and Pentachlorophenol

In order to study the influence of the UV-visible absorption spectra and fluorescence spectrum from 2,4-dichlorophenol (2,4-dcp), 2,4,6-trichlorophenol (2,4,6-tcp) and pentachlorophenol (ptcp) in different solvents. Using methanol, tetrahydrofuran (THF), ethanol, dimethyl sulfoxide (DMSO) and acetone solvent models, computer simulation prediction and analysis of the three chlorophenols were carried out. It provides a reference for the choice of solvents in the determination of chlorophenols by the Ultraviolet-Vis absorption spectrophotometry and fluorescence intensity detection.

Determination and analysis of solubility of brassinolide in different solvent systems at different temperatures (T = 278.15–323.15 K)

Brassinolide is a new environmental protection plant growth regulator. With the aim of knocking down selfcost and scale up agriculture market-place emulation, come what will manufacture method is adopted, the final step crystallization is significant for getting exclusive substances. The purpose of this study is to provide some authentic and general energetics data for the actual industrial production of brassinolide. In the research, the solid–liquid equilibrium of brassinolide in twelve pure solvents (tetrahydrofuran, dimethyl sulfoxide, ethanol, acetone, methanol, trichloromethane, acetonitrile, 1-butanol, isopropanol, xylenes, n-hexane and n-heptane) and three binary solvent mixtures (trichloromethane + tetrahydrofuran, acetonitrile + tetrahydrofuran and n-hexane + tetrahydrofuran) were tested by the circumstance of atmosphere pressure at range temperatures between 278.15 K and 323.15 K. Four models like the Buchowski–Ksiazaczak λh model, the modified Apelblat model, the Jouyban-Acree-van't-Hoff model and the Redich-Kister (CNIBS/R-K) model were employed to describe the change trend of solubility. On the groundwork of a series of data analysis, tetrahydrofuran is a better organic solvent and n-hexane can be applied as an effective anti-solvent when separating out brassinolides. These solubility data are very important for optimizing the extraction process and recrystallization of brassinolide.

Switching the Local Symmetry from D5h to D4h for Single-Molecule Magnets by Non-Coordinating Solvents

A solvent effect towards the performance of two single-molecule magnets (SMMs) was observed. The tetrahydrofuran and toluene solvents can switch the equatorial coordinated 4-Phenylpyridine (4-PhPy) molecules from five to four, respectively, in [Dy(OtBu)2(4-PhPy)5]BPh41 and Na{[Dy(OtBu)2(4-PhPy)4][BPh4]2}∙2thf∙hex 2. This alternation significantly changes the local coordination symmetry of the Dy(III) center from D5h to D4h for 1 and 2, seperately. Magnetic studies show that the magnetic anisotropy energy barrier of 2 is higher than that of 1, while the relation of blocking temperature is just on the contrary due to the symmetry effect. The calculations of the electrostatic potential successfully explained the driving force of solvents for the molecular structure change, confirming the feasibility of adjusting the performance of SMMs via diverse solvents.

Precise synthesis of α,ω-chain-end functionalized poly(dimethylsiloxane) with azide groups based on metal-free ring-opening polymerization and a quantitative azidation reaction

We have so far developed a method for the controlled ring-opening polymerization of cyclotrisiloxane catalyzed by strong organobasic compounds to produce various chain-end functionalized polysiloxanes with controlled number-average molar mass (Mn) and narrow molar-mass dispersity (ÐM) values. In this study, well-defined α,ω-chain-end functionalized poly(dimethylsiloxane) with azide groups (N3-PDMS-N3) possessing a narrow ÐM range (ÐM = 1.04) and a relatively high Mn of up to 28.2 kg mol−1 was precisely synthesized in a mixed solvent of tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) in the presence of quaternary ammonium salts as catalysts; N3-PDMS-N3 was obtained by converting α,ω-chain-end functionalized PDMS with bromomethyl groups (Br-PDMS-Br), which was prepared by polymerizing hexamethylcyclotrisiloxane (D3), water, and 1,3-trimethylene-2-n-propylguanidine (TMnPG) as the monomer, the initiator, and the catalyst, respectively. It was necessary to choose proper solvents depending on the Mn of Br-PDMS-Br to achieve the complete conversion of the bromomethyl groups by the azidation reaction. Moreover, we demonstrate the model reaction of copper-catalyzed 1,3-dipolar cycloaddition between N3-PDMS-N3 and phenylacetylene. As a result, the cycloadducted compound was exclusively obtained while maintaining a low ÐM value of 1.06 by employing copper(I) bromide and triethylamine as the catalyst and the ligand, respectively. This system was also effective for a polymer-polymer coupling reaction. Indeed, we successfully synthesized an ABA-type triblock copolymer where A and B are polystyrene (PS) and PDMS segments by reacting N3-PDMS-N3 with ω-chain-end functionalized PS with an alkynyl group.

Solvent mixtures in pharmaceutical development: Maximizing the API solubility and avoiding phase separation

Knowing the solubilities of active pharmaceutical ingredients (APIs) in pure solvents and solvent mixtures is essential for several manufacturing aspects of pharmaceutical product development. In this paper, we demonstrate that time-consuming and costly experiments can be reduced to a minimum using the thermodynamic model Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) that can simultaneously predict API solubilities in pure solvents and solvent mixtures as well as unwanted liquid-liquid phase separation (LLPS). We investigated the temperature-dependent solubility of naproxen, ritonavir, and indomethacin in the solvents acetone, dichloromethane, ethanol, ethyl acetate, methanol, 2-propanol, tetrahydrofuran, and water, and mixtures thereof. Solvent mixtures with predicted enhanced API solvation properties (cosolvency) were validated by experiments. Moreover, concentration regions in which LLPS was predicted to occur were also found to be in perfect agreement with the experimental data.

Chiral Supramolecular Polymers Assembled by Amphiphilic Oligopeptide-Perylene Diimides and High Electrochemical Sensing.

Various secondary structures, for example, β-sheet hydrogen bonds formed by oligopeptides exhibiting high directionality and selectivity provide a new avenue to regulate optoelectronic performances of supramolecular assemblies constructed by π-conjugated chromophores. In this work, oligopeptide-perylene diimides (AUPDIs) are synthesized to generate β-sheet strands which guide the formation of chiral supramolecular polymers with a diversity of morphologies in combination with the π-π stacking even in aqueous media. Complex morphology transitions are successfully controlled by simply adjusting the water volume fraction in the binary solvent of water and tetrahydrofuran from spherical hollow aggregates to long helical nanowires and to short nanofibers. The mechanism of the assembly changes from cooperative to the isodesmic model relying on AUPDI concentrations. This originates from the transformation in the β-sheet that regulates profoundly the arrangement of the AUPDI molecules. Prominently efficient and positive electronic sensing to triethylamine for highly helical nanowires engenders due to the highly ordered helical arrangement within the nanowires, fourfold of the short nanofibers.

Dynamic Surfaces-Degradable Polyester Networks that Resist Protein Adsorption.

We synthesized a series of novel degradable alternating copolyesters composed of diglycolic anhydride (DGA) and two epoxides, epoxymethoxytriethylene glycol (ETEG) and a photoactive crosslinking agent epoxy benzophenone (EBP). After UV crosslinking, soaking the films in a good solvent (tetrahydrofuran) removed uncrosslinked material, and the resulting film gel fractions were calculated. These network films were then degraded in buffer solutions of varying pH values. The degradation of networks with lower gel fraction (fewer crosslinks) was faster and followed first-order kinetics. In contrast, the denser network degraded slower and followed zeroth-order kinetics. The lower gel fraction networks possess a higher swelling ratio and resist bovine serum albumin (BSA) adsorption better by entropic shielding and faster degradation. In comparison, higher gel fraction networks with higher EBP mole fractions adsorb more BSA due to hydrophobic interactions and slower degradation.

Negative Cooperativity in Guest Binding of a Ditopic Self-Folding Biscavitand.

A brand-new self-folding biscavitand was synthesized from a feet-to-feet-connected bisresorcinarene. The X-ray crystal structure of the biscaivtand showed that the two cavities are tightly connected with four butylene linkages. The conformationally coupled two cavities accommodated two cationic guests, showing a homotropic negative cooperativity in nonpolar solvents (toluene and chloroform). A polar tetrahydrofuran solvent weakened the cyclic hydrogen bonding interactions of the biscavitand, which resulted in noncooperative guest binding.

All-Polymer Indoor Photovoltaic Modules

Indoor photovoltaic (IPV) with power output over 100 μW is promising to power the numerous sensor nodes in Internet of Things (IoT) ecosystem. All polymer photovoltaic has the advantages of excellent thermal stability and superior mechanical property. In this work, we fabricate the first all-polymer indoor photovoltaic module with the active area of 10 cm2. The module uses polymer doner CD1 and new polymer acceptor PBN21 with medium optical bandgap of 1.9 eV as the active layer. It is processed with ecofriendly solvent tetrahydrofuran and the morphology can be improved by blade coating at 55 oC. Under light emitting diode illumination at 1000 lux, the module exhibits a power conversion efficiency of 12.04% and a power output of 367.2 μW. The sufficient power output, high efficiency, excellent stability and eco-friendly processing indicate that allpolymer indoor photovoltaic is a promising approach to achieve the self-powered of sensor nodes in IoT ecosystem.

A novel dopant for spiro-OMeTAD towards efficient and stable perovskite solar cells

2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD), as the most common used hole transport material (HTM), plays a significant role in the normal structured (n-i-p) high-efficiency perovskite solar cells (PSCs). In general, it is prepared by a halogen solvent (chlorobenzene, CBZ) and needs an ion dopant (lithium bis (trifluoromethanesulfonyl)imide, Li-TFSI) to improve its conductivity and hole mobility. However, such a halogen solvent is not environmentally friendly and the widely used Li-TFSI dopant would affect the stability of PSCs. Herein, we develop a non-halogen solvent—tetrahydrofuran (THF)-prepared spiro-OMeTAD solution with a new p-type dopant, potassium bis(fluorosulfonyl)imide (K-FSI), to apply into PSCs. By this strategy, high-hole-mobility spiro-OMeTAD film is achieved. Meanwhile, the potassium ions introduced by diffusion into perovskite surface passivate the interfacial defects. Therefore, a hysteresis-free champion PSC with an efficiency of 21.02% is obtained, along with significantly improved stability against illumination and ambient conditions. This work provides a new strategy for HTMs toward hysteresis-free high-efficiency and stable PSCs by substituting dopants.

Optical properties of PVC composite modified during light exposure to give high absorption enhancement

Modified poly(vinyl chloride) (PVC) films have been synthesized with a simple superficial deposition by using solvent tetrahydrofuran (THF). These modified films were prepared by a casting method over a glass substrate. Different types of the amino group with a suitable aromatic aldehyde as an organic compound, which were reacted to prepare different PVC composite films. These films have been analyzed by UV-Visible spectra. The percentage of PVC was (0.25 g) with (0.05 g) amino group and aromatic aldehyde combinedly, then dissolved with (8 ml) of tetrahydrofuran (THF) at room temperature (300 K). The optical properties as absorption coefficient, reflectance, transmittance, skin depth, energy gap, refractive index, extinction coefficient, and urbach energy were studied. The transmittance value of the pure PVC film was 1.0 then declined gradually after dispersion with the compounds to the lowest value at 0.1, the reflectance also decreased. The energy gap for direct allowed decreased from (5.1 to 2.9 eV), and indirect transition decreased also from (5.0 to 2.8 eV), this behavior indicate that the modified films become work as semi-crystalline compounds toward the light. In tailoring, the optical properties, and urbach energy have been increased after mixed with PVC polymer. The scattering energy (Ed) and the effective single oscillator (Eo), were decreased. In a similar manner the dielectric constant high frequency (ε∞) and effective mass (Nm*), of dielectric constants were increased for PVC modified films. The PVC modified films are appropriate for anti-reflected coating while being good suitable in high refractive lenses and photovoltaic cells applications.

Solubility measurement and thermodynamic modelling of curcumin in twelve pure solvents and three binary solvents at different temperature (T = 278.15–323.15 K)

In the research, the solubility of curcumin was studied by static equilibrium method combined with HPLC. The solubility data of curcumin was measured in twelve pure solvents (dimethyl sulfoxide, tetrahydrofuran, acetone, ethyl acetate, isopropanol, acetonitrile, 1-butanol, ethanol, methanol, xylenes, n-hexane and n-heptane) and three binary solvent mixtures (acetone + tetrahydrofuran, acetonitrile + tetrahydrofuran and n-hexane + tetrahydrofuran) at different temperature (T = 278.15–323.15 K) under atmospheric pressure. The solubility values demonstrate that the solubility increased with the increase of temperature in all solvents. The modified Apelblat model and the Buchowski-Ksiazczak λh model were used to fitted the solubility data in pure solvents, the combined nearly ideal binary solvent/ Redlich-Kister (CNIBS/R-K) model and the Jouyban-Acree model were employed to adopt the solubility data in binary solvent mixtures. The RADmax of the modified Apelblat model and the λh model are 2.621% and 5.831%, the RMSDmax are 6.9 × 10-4 and 1.62 × 10-3, respectively. The RADmax of the CNIBS/R-K model and the Jouyban-Acree model are 2.249% and 4.901%, the RMSDmax are 9.33 × 10-3 and 3.67 × 10-3. Meanwhile, the KAT-LSER model was used to explore the effect of the solvation of curcumin. The fitting results of all equations prove the accuracy of the experimental data, these solubility data are very important for optimizing the extraction process and recrystallization of curcumin.

How acid can become a dihydrogen complex in water? A DFT study

To accurate know the acidity of a dihydrogen molecule coordinated to a transition metal ion in water medium is an issue of interest in many areas, from electrochemistry to enzymes and catalysis. However, experimental determination of this magnitude is challenging, and very few values have been reported. In this article we describe a computational protocol, based on DFT calculations and employing a discrete-continuum solvent representation, to estimate pKawater of transition metal dihydrogen complexes. In this approach the number of solvent molecules explicitly included in the calculations is determined by the convergence with the solvation Gibbs energy of the proton in the solvent. The approach has been initially validated with experimental data in tetrahydrofuran (THF) solvent. Using (THF)3 clusters a mean absolute deviation from experiments of only 1.4 pKa unit is achieved. In water the convergence is reached with (H2O)10 clusters. Using them in a discrete-continuum model, the pKawater of twelve dihydrogen complexes experimentally characterized in water have been computed. pKawater values span a wide range, from 23 to -4, illustrating how coordination to a transition metal modifies the dihydrogen acidity. Decomposition of the ∆G of the acid-base equilibrium in two contributions, one intrinsic to the complex and another one accounting for solvent effects enables a deeper analysis of the dihydrogen acidities.

Synthesis of fuel bioadditive by esterification of glycerol with acetic acid over hydrophobic polymer-based solid acid

The transformation of glycerol into high value-added derivatives has been of critical importance from the viewpoint of sustainable production of biodiesel. Among the reported processes, selective esterification of glycerol with acetic acid to a fuel bioadditive, including glycerol diacetate (DAG) and glycerol triacetate (TAG), is a research hot topic in both academic research and industrial application. In this work, a series of polydivinylbenzene-based solid acids (PDS) with different structural performances were prepared by a hydrothermal synthesis method and employed as catalysts for the acetylation of glycerol with acetic acid to DAG and TAG. The effects of PDS structure properties on the catalytic performance are discussed in detail with the help of various characterizations. PDS-THF prepared in tetrahydrofuran solvent was proven to be the most active catalyst among all the tested samples. In addition, glycerol could be almost completely converted into glyceryl acetates in the presence of PDS-THF, with a combined selectivity to DAG and TAG of 88.6% at its optimization condition. No obvious deactivation can be observed for PDS-THF after five runs, and the synergism of abundant acidic sites, suitable acidic site density and super hydrophobicity can account for its superior catalytic performance.

Self-Assembly of Single-Diamond-Surface Networks.

Biological scaffolds with hyperbolic surfaces, especially single gyroid and single-diamond structures, have sparked immense interest for creating novel materials due to their extraordinary physical properties. However, the ability of nature to create these unbalanced surfaces has not been achieved in either lyotropic liquid crystals or block copolymer phases due to their thermodynamical instability in these systems. Here, we report the synthesis of a porous silica scaffold with a single-diamond-surface structure fabricated by self-assembly of the poly(ethylene oxide)-b-polystyrene-b-poly(L-lactide) and silica precursors in a mixed solvent of tetrahydrofuran and water. The single-diamond structure with tetrahedral interconnected frameworks was revealed by the electron crystallographic reconstruction. We assume that the formation of single networks is induced by the structural transition and related to the energetic change due to the fluctuations of the Gaussian curvature. This work may provide new insights into these biologically relevant surfaces and related self-assembly systems.

Self‐Assembly of Single‐Diamond‐Surface Networks

AbstractBiological scaffolds with hyperbolic surfaces, especially single gyroid and single‐diamond structures, have sparked immense interest for creating novel materials due to their extraordinary physical properties. However, the ability of nature to create these unbalanced surfaces has not been achieved in either lyotropic liquid crystals or block copolymer phases due to their thermodynamical instability in these systems. Here, we report the synthesis of a porous silica scaffold with a single‐diamond‐surface structure fabricated by self‐assembly of the poly(ethylene oxide)‐b‐polystyrene‐b‐poly(L‐lactide) and silica precursors in a mixed solvent of tetrahydrofuran and water. The single‐diamond structure with tetrahedral interconnected frameworks was revealed by the electron crystallographic reconstruction. We assume that the formation of single networks is induced by the structural transition and related to the energetic change due to the fluctuations of the Gaussian curvature. This work may provide new insights into these biologically relevant surfaces and related self‐assembly systems.

Quantitative Structure-Property Relationship Modelling for the Prediction of Singlet Oxygen Generation by Heavy-Atom-Free BODIPY Photosensitizers*.

Heavy‐atom‐free sensitizers forming long‐living triplet excited states via the spin‐orbit charge transfer intersystem crossing (SOCT‐ISC) process have recently attracted attention due to their potential to replace costly transition metal complexes in photonic applications. The efficiency of SOCT‐ISC in BODIPY donor‐acceptor dyads, so far the most thoroughly investigated class of such sensitizers, can be finely tuned by structural modification. However, predicting the triplet state yields and reactive oxygen species (ROS) generation quantum yields for such compounds in a particular solvent is still very challenging due to a lack of established quantitative structure‐property relationship (QSPR) models. In this work, the available data on singlet oxygen generation quantum yields (ΦΔ) for a dataset containing >70 heavy‐atom‐free BODIPY in three different solvents (toluene, acetonitrile, and tetrahydrofuran) were analyzed. In order to build reliable QSPR model, a series of new BODIPYs were synthesized that bear different electron donating aryl groups in the meso position, their optical and structural properties were studied along with the solvent dependence of singlet oxygen generation, which confirmed the formation of triplet states via the SOCT‐ISC mechanism. For the combined dataset of BODIPY structures, a total of more than 5000 quantum‐chemical descriptors was calculated including quantum‐chemical descriptors using density functional theory (DFT), namely M06‐2X functional. QSPR models predicting ΦΔ values were developed using multiple linear regression (MLR), which perform significantly better than other machine learning methods and show sufficient statistical parameters (R=0.88–0.91 and q2=0.62–0.69) for all three solvents. A small root mean squared error of 8.2 % was obtained for ΦΔ values predicted using MLR model in toluene. As a result, we proved that QSPR and machine learning techniques can be useful for predicting ΦΔ values in different media and virtual screening of new heavy‐atom‐free BODIPYs with improved photosensitizing ability.

Bis(1-methyl-imidazole)[meso-α,α,α,α-tetra-kis(o-nicotinamido-phen-yl)porphinato]iron(II)-1-methyl-imidazole-tetra-hydro-furan (1/1/1.5).

In the title compound, [FeII(C68H44N12O4)(C4H6N2)2]·C4H6N2·1.5C4H8O, the central FeII ion is coordinated by four pyrrole N atoms of the porphyrin core and two N atoms of the 1-methyl-imidazole ligands in the axial sites. One 1-methyl-imidazole and one and a half tetra-hydro-furan solvent mol-ecules are also present in the asymmetric unit. The complex exhibits a near planar porphyrin core conformation, in which the iron centre is slightly displaced towards the hindered porphyrin side (0.01 Å). The average Fe-Np (Np refers to the pyrrole nitro-gen atoms in the porphyrin) bond length is 1.990 (9) Å, and the axial Fe-NIm (NIm refers to the imidazole nitro-gen atoms) bond lengths are 1.993 (3) and 2.004 (3) Å. The dihedral angle between the two coordinated 1-methyl-imidazole planes is 56.6 (2)°. The dihedral angles between the 1-methyl-imidazole planes and the planes of the closest Fe-Np vector are 16.8 (2) and 39.8 (2)°. N-H⋯N and N-H⋯O inter-actions are observed in the crystal structure.

Mild, Efficient and Metal‐Free Strategies for Direct Diamination of α, β‐Unsaturated Ketones Using Different Iodine Sources

AbstractReaction of α, β‐unsaturated ketone (chalcone) and secondary amine leads to direct diamination of chalcone by dehydrogenation and forming two C−N bonds. This diamination reaction of chalcones with morpholine has been carried out through two effective protocols. The use of N‐iodosuccinimide (NIS) in tetrahydrofuran solvent in one strategy, while the combination of NH2OH ⋅ HCl and NaIO4 in dichloromethane solvent in another are very effective and work at room temperature. No other additives are required for this conversion. Mild and metal free conditions, simple operation technique, good to excellent yields are the notable advantages of both these protocols.

Determination of 13 sunscreen agents in cosmetics by gas chromatography-mass spectrometry

防晒剂广泛应用于化妆品中,是目前化妆品监管的重点。建立了同时测定化妆品中13种防晒剂的气相色谱-质谱(GC-MS)方法。化妆品样品经二氯甲烷提取后,涡旋超声后稀释。采用程序升温模式,经HP-5ms毛细管色谱柱(30 m×250 μm×0.25 μm)在30 min内对13种防晒剂实现分离,经电子轰击(EI)源电离后采用选择离子监测模式(SIM)扫描测定,外标法定量。比较了6种常用有机溶剂的基质效应和平均回收率,二氯甲烷的基质效应弱,平均回收率较高。13种防晒剂在相应的线性范围内线性关系良好,相关系数均大于0.998,检出限(LOD, S/N=3)为0.04~0.63 mg/g,定量限(LOQ, S/N=10)为0.12~2.10 mg/g。实验选取了两种基质,在3个水平下验证方法的回收率和精密度,13种防晒剂在霜类基质中的加标回收率为88.7%~103.6%,相对标准偏差(RSD, n=6)为1.7%~4.9%,在乳类基质中的加标回收率为88.4%~102.3%, RSD(n=6)为1.2%~3.9%。美白类化妆品常添加防晒剂成分,为监管盲区,采用该方法检测了5批含有防晒剂的美白类化妆品,其所含5种防晒剂的含量为0.8%~5.2%,符合相关要求。该方法操作简单,灵敏度高,回收率好,测定的13种防晒剂均为我国《化妆品安全技术规范》2015版规定的常用的限用组分,可以用于各类化妆品中13种防晒剂的定性定量测定,为市场监管和实验室检测提供新的技术支持。