Hydrogen Bond Acceptor Research Articles

Experimental and mechanism study on the separation of isobutyl alcohol and water azeotrope using hydrophobic deep eutectic solvents

Isobutyl alcohol with good miscibility, high octane number and energy density has been paid more and more attention in the field of new biofuels, as it is an ideal alternative fuel for gasoline. However, isobutyl alcohol and water azeotrope need a clean and efficient separation method to realize the separation in isobutyl alcohol production process and industrial wastewater. Three hydrophobic deep eutectic solvents (DESs) were used to separate isobutyl alcohol. Decanoic acid was used as hydrogen bond donor and menthol, thymol and lidocaine were used as hydrogen bond acceptors to synthesize DESs. The liquid-liquid equilibrium experiment was carried out for the system containing DESs and MSD −water at 101.3 kPa and 303.15 K, and the separation effect of different DESs was indicated using distribution coefficient (β) and selectivity (S). The σ-Profile can be a good reflection of the strength of a substance's ability to accept and provide hydrogen bonds. The interaction energy and self-diffusion coefficient of the separation system were described quantitatively by molecular dynamics simulation. The relationship between DESs and the separation system was analyzed quantitatively by radial distribution function and spatial distribution function. The separation results show that the three DESs have good separation effect on isobutyl alcohol-water system, among which the DESs synthesized by thymol and decanoic acid has the best separation effect, and the interaction of isobutyl alcohol-water separation process is controlled by van der Waals forces. DESs plays an important role in the separation and treatment of isobutyl alcohol-containing wastewater, and promotes the sustainable development of wastewater treatment projects to save costs and increase production benefits.

Achieving Highly Stable Zn Metal Anodes at Low Temperature via Regulating Electrolyte Solvation Structure.

Zinc metal is an attractive anode material for rechargeable aqueous Zn-ion batteries (ZIBs). However, the dendrite growth, water-induced parasitic reactions, and freezing problem of aqueous electrolyte at low temperatures are the major roadblocks that hinder the widely commercialization of ZIBs. Herein, tetrahydrofuran (THF) is proposed as the electrolyte additive to improve the reversibility and stability of Zn anode. Theoretical calculation and experimental results reveal that the introduction of THF into the aqueous electrolyte can optimize the solvation structure which can effectively alleviate the H2O-induced side reactions and protect the Zn anode from corrosion. Moreover, THF can act as a hydrogen bond acceptor to interact with H2O, which can greatly reduce the activity of free H2O in electrolytes and improve the low-temperature electrochemical performance of Zn anode. As a result, the Zn anodes demonstrate high cyclic stability for 2800h at 27°C and over 4000h at -10°C at 1.0mA cm-2 /1.0mAhcm-2. The full cell exhibits excellent cyclic stability and rate capability at 27 and -10°C. This work is expected to provide a new approach to regulate the aqueous electrolyte and Zn anode interface chemistry for highly stable and reversible Zn anodes.

Cresyl violet electropolymerization on functionalized multiwalled carbon nanotubes in carboxylic acid based ternary deep eutectic solvents for hydroquinone sensing

The phenazine dye cresyl violet (CVio) has been evaluated as precursor for the preparation of a new electrochemical sensor based on poly(cresyl violet) deposited on multiwalled carbon nanotube (CNT) modified glassy carbon electrodes (GCE) in neutralized acid-doped ternary deep eutectic solvents (DES). DES with choline chloride as hydrogen bond acceptor and with different hydrogen bond donors (HBD), namely acetic acid, ethylene glycol and oxalic acid were evaluated for CVio electropolymerization by potential cycling. The best polymer films were obtained in ternary DES with the two HBD acetic acid plus ethylene glycol doped with H2SO4 and followed by NaOH neutralization. Electrochemical characterization (voltammetric and electrochemical impedance) showed the formation of anthraquinone groups during electropolymerization, which is initiated on the CNT by the formation of a cation radical. Anthraquinones in the polymer film led to an increased response at the modified electrode for the determination of hydroquinone (H2Q) with low LOD (0.25 µmol L−1) in a broad linear range (1–80 µmol L−1), with good reproducibility, repeatability, and stability. The sensor was successfully applied to the quantification of H2Q in dermatological creams with no matrix effect towards hydroquinone response.

Stabilizing graphene oxide with complementary nanosheets for robust membranes with high flux

Laminar assembles of graphene oxide (GO) are receiving tremendous attention for their interesting nanofluidic behaviors, but suffer from structural instability and frustrated mass transfer. Herein, we stabilize GO assembles by “complementary nanosheets”, and thus obtain highly robust and permeable membranes. Self-exfoliated nanosheets of ionic covalent organic frameworks (iCONs) are intercalated into GO nanosheets. GO and iCONs are physicochemically complementary as they carry opposite charges and hydrogen bonds acceptors and donors, respectively. Upon mixing, they form laminar assembles locked by electrostatic attraction and hydrogen bonds, suppressing swelling in water. Moreover, simulation and experimental results reveal that iCONs expands the interlayer distance and provides additional mass-transport paths. Consequently, the GO/iCONs membranes exhibit ultra-high water permeance up to 11-fold larger than that of pure GO membranes. This work provides a controllable route to stabilize GO assembles, and develops new membranes using complementary two-dimensional structures as building blocks.

Architecture of integrated solid-state zinc-ion battery based on sodium alginate gelation

How to construct a new electrode/electrolyte interface structure in solid-state batteries (SSBs), enhance interface stability, and improve the cycling performance of SSBs is a great challenge for the development of SSBs. Here, an all-in-one “interface-free” structure was developed. This interfacial structure constructs a full-interface hydrogen bonding network through the abundant hydrogen bond donors and acceptors in the cathode and electrolyte to enhance the interfacial stability and avoid interfacial failure during charging and discharging, and generates cathode–electrolyte interface (CEI) in-situ to effectively regulate zinc ion transport. Square cells assembled in this structure are stabilized for 100 cycles at a current density of 0.1 mA cm−2. This integrated electrode provides a new idea for the long stable cycle of SSBs.

Discovery of Small‐Molecules as Potential GSK‐3β Inhibitors for the Treatment of Alzheimer's Disease Using Pharmacophore‐Based Virtual Screening

AbstractGlycogen synthase kinase‐3β (GSK‐3β) plays pivotal role in regulating diverse range of cellular functions. It plays negative role in cellular signaling pathways and believed to involved in the pathologies of various diseases like neurological disorders, type II diabetes, inflammation, cardiac hypertrophy, cancer and bipolar disorders. GSK‐3β is proposed as a promising target for drug discovery in treating these disease conditions. A number of structurally different chemical scaffolds including pyrimidinone derivatives have been identified as potential GSK‐3β inhibitors. In the current study, PHASE module of Schrödinger 3D QSAR was used on about 157 pyrimidinone derivatives for the development of statistically significant PLS model. Consecutively, the best pharmacophore hypothesis with features like three hydrogen bond acceptors (A1‐3), two hydrophobic regions (H1 and H2), and one aromatic ring (R1), was selected to screen ZINC and PUBCHEM databases. Molecules with matching pharmacophoric features and ROF were subjected to structure‐based virtual screening (HTVS→SP→XP) and MMGBSA. Two hits from each library were selected for MD simulation studies that showed good pharmacokinetic properties, binding score (−6.8–−8.8 kcal/mol) and ▵GMMGBSA (−55.80–−58.1 kcal/mol) as compared to the reference molecule, NP‐12. Similarly, MD simulation, and MMPBSA identified three compounds i. e. ZINC67743231, ZINC01582756, and PUBCHEM11553018 displaying stability in the binding pocket and demonstrated better binding affinity of −22.07, −27.33, and −30.61 kcal/mol, respectively, within the active site of GSK‐3β. DFT studies also demonstrated the stability of these three lead compounds with a high energy gap between HOMO and LUMO ranging between 0.14546 and 0.1718 eV.

Physical absorption and thermodynamic modeling of CO2 in new deep eutectic solvents

Due to the advantages of deep eutectic solvents (DESs), such as good CO2 absorption performance, excellent biodegradability, low cost, and simple synthesis, attention has been drawn to selecting DESs with high efficiency for capturing CO2 in a green and environmentally compatible context. In the present study, acetamide as the hydrogen bond acceptor (HBA) and diethylene glycol, 1,2-propanediol, and 1,3-propanediol as the hydrogen bond donors (HBD) for the synthesis of DESs. First, the density and viscosity of these prepared DESs were measured under standard ambient pressure and at temperatures ranging between 293 K and 343 K. Subsequently, the CO2 solubility in DESs was ascertained by the isovolumetric saturation experimental method. The results indicated that all synthesized DESs exhibited physical absorption of CO2 and the diethylene glycol-based DESs had the highest dissolvability for CO2. For the DES with diethylene glycol and 1,2-propanediol as HBD, the CO2 solubility increased as the molar ratio of HBD decreased. On the contrary, the amount of CO2 adsorbed by 1,3-propanediol-based DES increased with increasing 1,3-propanediol content. The semi-empirical Jou and Mather model allows for an efficient correlation to be made among experimentally determined CO2 solubilities, temperatures, and the CO2 partial pressures. Comparing the deviations between the experimental and fitted values, the average relative deviation is small. By estimating the Henry constants and Manuscript File Click here to view linked References comparing them with the literature, it was demonstrated that the synthesized DESs are competitive in absorbing CO2.

Experimental and simulation study on the solubility of 1-naphthylamine in twelve neat solvents

To meet the demand of separating and purifying 1-naphthylamine from the reaction production and filling the solubility data gap, the solubility of 1-naphthylamine in twelve pure solvents (acetone, acetonitrile, ethyl acetate, n-butyl acetate, cyclohexane, n-heptane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, and iso-butanol) was experimentally investigated in the range from 273.15 K to 308.15 K. It was found that the solubility of 1-naphthylamine increases markedly with increasing temperature in all solvent systems. The maximum solubility was 0.8978 (in the solvent of acetone,T = 308.15 K) and the minimum solubility was 0.005485 (in the solvent of n-heptane, T = 273.15 K). Then the experimental solubility data was correlated by the modified Apelblat model, Van't Hoff model, NRTL model, Wilson model, and Margules model. ARD% was calculated to assess the accuracy of the five equations and the results indicated that the modified Apelblat model fits optimally with an average ARD% value of 1.62 %. The effects of various physicochemical properties such as solvent polarity, hydrogen bond donor, hydrogen bond acceptor, and cohesive energy density on solute dissolution behavior were explored. In addition, the apparent thermodynamic properties of 1-naphthylamine in different solvents were analyzed based on modified Van’t Hoff model, which indicated the dissolution process of 1-naphthylamine in selected solvents is endothermic and entropy-driving. Finally, the effect of intermolecular interactions on the dissolution behavior was investigated at the molecular scale through molecular dynamics simulation studies, including molecular electrostatic potential surface, solvation free energy and radial distribution function analysis. This work will provide a fundamental guidance for the crystallization, separation, and purification of 1-naphthylamine.

Green extraction of phenolic compounds from strawberry waste based on natural deep eutectic solvents

SummaryThe increase in ecological sensitivity and the interest in ‘green chemistry’ are leading to a decrease in the use of environmentally harmful substances in chemical processes. Replacing traditional solvents with NaDES (Natural Deep Eutectic Solvents) is an excellent green alternative to extract bioactive compounds from agri‐food industry wastes, as these solvents bring numerous advantages and are environmentally friendly. In this work, the performance of traditional organic solvents and NaDES were compared for the extraction of phenolic compounds (PCs), with different physicochemical characteristics, from strawberry residues. For this reason, numerous combinations of NaDES have been evaluated, optimising the experimental conditions of the process. The samples were analysed using HPLC–MS/MS, which allowed the identification and quantification of numerous PCs in the samples. The best extraction efficiencies were obtained using choline chloride (ChCl) as hydrogen bond acceptor and lactic acid (LA) as hydrogen bond donor, in a ratio of 1:5 and containing 30% of water. Isoquercetin, hesperidin and catechin were the phenolic compounds most remarkable in samples, with a content of ca. 43%, 26% and 11% of total polyphenols, respectively. Finally, the evaluation of the method through the Analytical GREEness calculator showed how NaDES can satisfactorily replace traditional extractions with a great performance and reduced impact on the environment.

Machine Learning Exploration of the Relationship Between Drugs and the Blood-Brain Barrier: Guiding Molecular Modification.

This study aimed to improve the efficiency of pharmacotherapy for CNS diseases by optimizing the ability of drug molecules to penetrate the Blood-Brain Barrier (BBB). We established qualitative and quantitative databases of the ADME properties of drugs and derived characteristic features of compounds with efficient BBB penetration. Using these insights, we developed four machine learning models to predict a drug's BBB permeability by assessing ADME properties and molecular topology. We then validated the models using the B3DB database. For acyclovir and ceftriaxone, we modified the Hydrogen Bond Donors and Acceptors, and evaluated the BBB permeability using the predictive model. The machine learning models performed well in predicting BBB permeability on both internal and external validation sets. Reducing the number of Hydrogen Bond Donors and Acceptors generally improves BBB permeability. Modification only enhanced BBB penetration in the case of acyclovir and not ceftriaxone. The machine learning models developed can accurately predict BBB permeability, and many drug molecules are likely to have increased BBB penetration if the number of Hydrogen Bond Donors and Acceptors are reduced. These findings suggest that molecular modifications can enhance the efficacy of CNS drugs and provide practical strategies for drug design and development. This is particularly relevant for improving drug penetration of the BBB.

Cooperativity between Intermolecular Hydrogen and Carbon Bonds in ZY···CH3CN/CH3NC···HX Trimers (ZY = H2O, H2S, HF, HCl, HBr, NH3, and H2CO; HX = HF, HCl, and HBr).

Hydrogen-bonding and carbon-bonding interactions are widespread in nature. We studied the cooperativity between these interactions in 42 trimeric complexes ZY···CH3CN/CH3NC···HX, where ZY molecules are H2O, H2S, HF, HCl, HBr, NH3, and H2CO, and HX molecules are HF, HCl, and HBr. Acetonitrile (CH3CN) and isoacetonitrile (CH3NC) act as hydrogen bond acceptors as well as carbon bond donors in these trimers. Various theoretical methods, such as electronic structure calculations, quantum theory of atoms in molecule (QTAIM), natural bond orbital (NBO), and reduced density gradient analysis, are employed to study these trimers, and the results are compared with the corresponding ZY···CH3CN/CH3NC and CH3CN/CH3NC···HX dimers. Electronic structure calculations are performed at the second-order Mo̷ller-Plesset perturbation theory using the 6-311++G(2d,2p) basis set. We show that both the interactions act synergistically in these trimers leading to an increase in their bond strength as compared to the strength in the individual dimers. The cooperative energies for these trimers are in the range of 0.69 to 3.22 kJ/mol. It is seen that the carbon bonds benefit more from the cooperativity than the hydrogen bonds. The trends of cooperativity and correlations of interaction energies and cooperative energies with relevant QTAIM and NBO parameters are reported.

Influence of water on the properties of hydrophobic deep eutectic solvent

Deep eutectic solvent (DES) shows excellent absorption performance in the field of CO2 capture. It is considered as a new green absorption solvent to replace monoethanolamine. In the industry, the presence of water not only affects the structural stability of the solvent, but also affects its thermophysical properties. In this work, three kinds of hydrophobic DES were prepared. Based on the study of their structural characteristics and thermal stability, the density and viscosity of DES with water mixture were measured in the temperature range of 298.15 ∼ 338.15 K at atmospheric pressure. It was demonstrated that the trace water did not destroy the structure of DES, but it formed hydrogen bonds with DES. The increase water destroyed the structure of DES and formed hydrogen bonds with hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA), respectively. Moreover, the hard sphere model was applied to study the viscosity, and after introducing the binary interaction parameter, the average absolute relative deviation of the mixture reduced to 4.4 ∼ 7.7 %.

Solvent Replacement Strategies for Processing Pharmaceuticals and Bio-Related Compounds—A Review

An overview of solvent replacement strategies shows that there is great progress in green chemistry for replacing hazardous di-polar aprotic solvents, such as N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP), and 1,4-dioxane (DI), used in processing active industrial ingredients (APIs). In synthetic chemistry, alcohols, carbonates, ethers, eucalyptol, glycols, furans, ketones, cycloalkanones, lactones, pyrrolidinone or solvent mixtures, 2-methyl tetrahydrofuran in methanol, HCl in cyclopentyl methyl ether, or trifluoroacetic acid in propylene carbonate or surfactant water (no organic solvents) are suggested replacement solvents. For the replacement of dichloromethane (DCM) used in chromatography, ethyl acetate ethanol or 2-propanol in heptanes, with or without acetic acid or ammonium hydroxide additives, are suggested, along with methanol acetic acid in ethyl acetate or methyl tert-butyl ether, ethyl acetate in ethanol in cyclohexane, CO2-ethyl acetate, CO2-methanol, CO2-acetone, and CO2-isopropanol. Supercritical CO2 (scCO2) can be used to replace many organic solvents used in processing materials from natural sources. Vegetable, drupe, legume, and seed oils used as co-extractants (mixed with substrate before extraction) can be used to replace the typical organic co-solvents (ethanol, acetone) used in scCO2 extraction. Mixed solvents consisting of a hydrogen bond donor (HBD) solvent and a hydrogen bond acceptor (HBA) are not addressed in GSK or CHEM21 solvent replacement guides. Published data for 100 water-soluble and water-insoluble APIs in mono-solvents show polarity ranges appropriate for the processing of APIs with mixed solvents. When water is used, possible HBA candidate solvents are acetone, acetic acid, acetonitrile, ethanol, methanol, 2-methyl tetrahydrofuran, 2,2,5,5-tetramethyloxolane, dimethylisosorbide, Cyrene, Cygnet 0.0, or diformylxylose. When alcohol is used, possible HBA candidates are cyclopentanone, esters, lactone, eucalytol, MeSesamol, or diformylxylose. HBA—HBA mixed solvents, such as Cyrene—Cygnet 0.0, could provide interesting new combinations. Solubility parameters, Reichardt polarity, Kamlet—Taft parameters, and linear solvation energy relationships provide practical ways for identifying mixed solvents applicable to API systems.

Regioselective amination of 4-methylene-5,7-dinitroquinazoline: a mechanistic consideration on non-conventional N-H—π interactions between amine and ethylene moiety

ABSTRACT Pi (π) interactions originating from the N-H bond of amine and ethylene moiety have been explored on the mechanism of aromatic nucleophilic substitution (ArSN) of the nitro group of 4-methylene-5,7-dinitroquinazoline with methylamine in the gas phase and solvent media within DFT framework. The free energy profiles confirmed that the amination should take place at peri-position and calculations support the one-step mechanism through a transition state with no intermediate in the reaction route. Stabilisation of peri-transition state by intramolecular weak interaction akin to hydrogen bonding N-H—CH2 = C leads to the regioselective amination at peri-position of 4-methylene-5,7-dinitroquinazoline. The intramolecular hydrogen bond interactions at N-H—CH2 = C in the peri-transition state are strongly supported by a red shift in N-H stretching vibrations in simulated IR spectra and are confirmed by studying energetics of amination of structural/electronic analogues of 4-methylene-5,7-dinitroquinazoline. The present study established that ethylene plays an important role as an efficient H-bond acceptor in fixing the regioselectivity at peri-position in the amination of 4-methylene-5,7-dinitroquinazoline. This is the first-ever report for the exploration of the role of ethylene moiety as a hydrogen bond acceptor in mediating the regioselectivity of organic reactions.

Response surface optimization for deep eutectic solvents extraction of bamboo shoots proteins

To enhance the protein extraction rate of bamboo shoots, the Response Surface Methodology was utilized to optimize the protein extraction process of Chimonobambusa purpurea Hsueh f. & T.P.Yi (syn. Chimonobambusa neopurpurea T.P.Yi) bamboo shoots. Choline chloride and proline were utilized as hydrogen bond acceptors in a total of eight deep eutectic solvents, whereas glucose, sucrose, glycerol, ethylene glycol, acetylpropionic acid, malic acid, and lactic acid were used as hydrogen bond donors. This work examined the protein extraction from bamboo shoots using deep eutectic solvents. Single-factor experiments were conducted to determine the optimal composition of the deep eutectic solvents, along with the ideal gradients of material-liquid ratio gradients, water content, extraction time, and water bath temperature. The impact and interplay of various variables on the protein extraction rate of bamboo shoots were examined using the Box-Behnken Design and Response Surface Methodology. Both the water bath temperature and the extraction time significantly influenced the protein extraction rate of bamboo shoots. Notably, the interaction between extraction time and water bath temperature had the most substantial effect on the protein extraction rate of bamboo shoots. The quadratic response surface regression equation for the protein extraction rate of bamboo shoots relative to the actual values of each factor was obtained as follows: Protein extraction rate = −193.3275 + 3.8395 A - 18.7075 B + 6.3285 C + 0.2125 AB - 0.0089 AC + 0.024 BC - 0.02885 A2 + 0.685 B2 - 0.06455 C2. Finally, this work predicted optimum extraction parameters for bamboo shoots with choline chloride-sucrose (molar ratio 1:2), a material-liquid ratio of 1:50, a water content of 74 %, an extraction time of 4 h, and a water bath temperature of 44 ℃. Under the optimal conditions, the protein extraction yield was 59.39±0.45 %, which aligned with the predicted value from the response surface fitting equation. This indicated that the optimised regression equation may have practical significance. Compared with conventional extraction using a sodium hydroxide (NaOH) solution, deep eutectic solvents extraction of bamboo shoots is more environmentally friendly, non-toxic and harmless. It provides a theoretical and experimental reference for industrial extraction and offers a reference for deep eutectic solvent development in bamboo shoot resource utilization.Key message:To enhance the protein extraction rate of bamboo shoots, the Response Surface Methodology was utilized to optimize the protein extraction process of bamboo shoots.

A perspective on cellulose dissolution with deep eutectic solvents

Currently, membrane manufacturing relies heavily on fossil-based solvents and polymers, resulting in significant negative impacts on human health and the environment. Thus, there is an urgent need for eco-friendly, low-toxicity, and sustainable solvents and polymers to comply with the United Nations’ sustainable development goals. Cellulose, as a green, natural, and abundant polymer, offers a sustainable source for membrane manufacturing. However, a significant challenge exists in dissolving cellulose due to strong intermolecular and intramolecular hydrogen bonds within cellulose molecules. Deep eutectic solvents (DESs), which contain both hydrogen bond donor and acceptor groups, have received significant attention as alternative solvents for cellulose dissolution owing to their low cost, low toxicity, environmentally friendly nature, ease of synthesis, and versatility. This review examines experimental studies, and theoretical approaches, highlighting key findings and factors influencing cellulose dissolution in deep eutectic solvents.

Oxidative desulfurization of fuels using alcohol-based DESs.

The presence of sulfur-containing compounds in fuel oil has become a major global issue due to their release of toxic sulfur dioxide. Hydrodesulfurization is a commonly used method for removing sulfur from fuel. However, new desulfurization techniques have been developed recently as hydrodesulfurization (HDS) is ineffective in removing refractory sulfur, e.g., BT, DBT, 4-MDBT. In this study, a series of deep eutectic solvent (DES) using ChCl, salicylic acid, oxalic acid, citric acid, and adipic acid as hydrogen bond acceptors and MeOH, EtOH, BuOH, EG, DEG, and TEG as hydrogen bond donors on different mole ratios were synthesized and then investigated the efficiency of these DESs in extracting sulfur from model and diesel fuel. Densities, viscosity, refractive index, and FTIR spectra of synthesized DESs were recorded. It also included oxidative desulfurization, which is a promising approach offering high selectivity, mild reaction conditions, low cost, and high efficiency. Hydrogen peroxide was selected as the oxidant in this study due to its excellent performance, commercial availability, and high proportion of active oxygen. [Citric acid: TEG] [1:7] and [adipic acid: TEG] [1:8] were found to be the most effective, removing up to 44.07% and 42.53% sulfur from model oil during single-stage extraction at 30°C using a solvent-to-feed ratio of 1.0 and was increased to 86.87% and 85.06% using successive extraction up to the fourth stage. On oxidation, extraction efficiencies were reported to be 98.98%, 87.79%, and 56.25% and 96.96%, 81.22%, and 44.51% for model oil containing DBT and diesel 1 and diesel 2 with DES [citric acid: TEG] [1:7] and [adipic acid: TEG] [1:8] respectively at 30°C using a solvent-to-feed ratio of 1.0. The study found that [citric acid: TEG] [1:7] exhibits better extraction performance in the deep desulfurization of fuels at an extraction temperature of 30°C.

Do Electrostatics Control the Diffusive Dynamics of Solitary Water? NMR and MD Studies of Water Translation and Rotation in Dipolar and Ionic Solvents.

NMR-based measurements of the diffusion coefficients and rotation times of solitary water and benzene at 300 K are reported in a diverse collection of 13 conventional organic solvents and 10 imidazolium ionic liquids. Proton chemical shifts of water are found to be correlated to water OH-stretching frequencies, confirming the importance of electrostatic interactions in these shifts. However, the influence of magnetic interactions in aromatic solvents renders chemical shifts a less reliable indicator of electrostatics. Diffusion coefficients (DB) and rotational correlation times (τB) of benzene in the solvents examined are accurately described as functions of viscosity (η) by DB ∝ η-0.81 and τB ∝ η0.64. Literature values of DB and τB in alkane and normal alcohols, which were not included among the solvents studied here, are systematically faster than predicted by these correlations, indicating that factors beyond solvent viscosity play a role in determining the friction on benzene. In contrast to benzene, water diffusion and rotation are poorly described in terms of viscosity alone, even in the dipolar and ionic solvents measured here. The present data and the substantial literature data already available on dilute water diffusion show a systematic dependence of DW on solvent polarity among isoviscous solvents. The aspect of solvent polarity most relevant to water dynamics is the ability of a solvent to accept hydrogen bonds from water, as conveniently quantified by the frequency of water's OH stretching band, ΔνOH. The friction on translation, ζtr = kBT/DW, and rotation, ζrot = kBTτW, are both well correlated by functions of the form ζ(η, ΔνOH) = a1ηa2 exp (a3ΔνOH), where the ai are adjustable parameters. Molecular dynamics simulations reveal a strong coupling between electrostatic and nonelectrostatic water-solvent interactions, which makes it impossible to dissect the friction on water into additive dielectric and hydrodynamic components. Simulations also provide a tentative explanation for the unusual form of the correlating function ζ(η, ΔνOH), at least in the case of ζrot.

Rapid and safe determination of vitamin B1 in dairy products, fruits, nuts and vitamin tablets: Combination of natural deep eutectic solvents, experimental design and artificial intelligence

A natural deep eutectic solvent-based sonication assisted liquid-phase microextraction (NDES-SA-LPME) combined with UV-Vis spectrophotometry was optimized for the analysis of thiamine (Vit-B1) in dairy products, fruits, nuts and vitamin tablets. Five NADES was prepared by blending different molar ratios of hydrogen bond acceptors (citric acid, malic acid, tartaric acid, choline chloride and betaine) and hydrogen bond donors (glucose, proline, and glycerol). Based on preliminary experiments, the central composite design was created for optimization of selected key extraction factors. The effects of factors on the extraction of Vit-B1 were investigated using artificial intelligence approaches. Validation of the NDES-SA-LPME method was performed by analysis of reference materials. Working ranges for model solutions and matrix matched solution were 8–500 µg L−1 and 15–400 µg L−1, respectively. Further, limits of detection for model solutions and matrix matched solution were 2.4 µg L−1 and 4.6 µg L−1, respectively. Finally, a matrix matching calibration approach was used to increase recovery results, and acceptable recovery data were obtained in range of 95.9%-118.4%. This study is the first report to apply artificial intelligence, experimental modelling and NDES together to the analysis of Vit-B1 in real samples.

Enhancing extraction of betalains from beetroot (Beta vulgaris L.) using deep eutectic solvents: optimization, bioaccessibility and stability

Deep eutectic solvents (DESs) are the next generation of green solvents that are considered for their stability and biocompatibility. This study used 10 different DESs synthesized from choline chloride, alcohols, organic acids and sugars. Red beet betalains were extracted using three conventional solvents and DESs. Characterization experiments of DESs suggested that the electrical conductivity, pH, viscosity, water activity, density and chemical structure were greatly affected by the composition of the hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD). Betacyanin, betaxanthin and total betalain contents ranges were 23.68–702.17, 21.49–467.77, and 45.17–1169.94 mg kg−1, respectively, with choline chloride (ChCl): glucose (Glu) (1:2) giving the highest values. ChCl:Glu was chosen for the optimization process considering the molar ratio (ChC = 1:Glu = 0.75–1.75), water content (15–35%) and temperature (30–60 °C) factors for the central composite design. The optimum conditions were recorded as 1:0.75 molar, 30.83% water content, and 30 °C, respectively. Under optimum conditions, the yields of betalain, betacyanin and betaxanthin were found to be 1192.17 ± 23.63, 738.83 ± 17.87, and 453.34 ± 5.93 mg kg−1, respectively. Bioaccessibility analysis and stability tests were performed on the extracts obtained under optimum conditions. Stability tests revealed that the betalains of red beetroot are less stable in the light than in the dark. Bioaccessibility values for betacyanin, betaxanthin, and betalain were found to be 44.67 ± 1.40, 75.02 ± 1.20, and 56.21 ± 1.33%, respectively. Green extraction of betalains from red beetroot using DES, such as ChCl:Glu, is promising for a strong stabilization and high bioaccessibility of betalains.Graphical