Hydrogen Bond Lengths Research Articles

A new derivative of 1-allyl-3-methylimidazolium chloride as ionic liquid compound: Synthesis, physical properties and DFT studies

This study aimed to improve the physical properties of 1-allyl-3-methylimidazolium chloride (AMIMCl) by synthesizing a new derivative, 1-allyl-2-hydroxymethyl-3-methylimidazolium chloride (AHMMIMCl). The synthesized AHMMIMCl was characterized using FT-IR, 1HNMR, 13CNMR, TGA, and DSC techniques, and its physical and computational properties were compared with those of AMIMCl. Experimentally, AHMMIMCl exhibited a lower viscosity (Δη =267.57 cP), a significantly reduced melting point (ΔT =∼100 °C), and lower conductivity (Δσmax=30.72 mS.cm−1 at 25 °C). The stable geometries of the cations, ion-pairs, and dimer structures were estimated employing DFT methods. The nature of the cation–anion interaction was analyzed by the natural bond orbital (NBO) and electrostatic potential (ESP) analyses. The physical properties of the newly synthesized compound are found to be in agreement with DFT calculations. Additionally, the new derivative demonstrated enhanced viscosity and melting point compared to the parent compound (AMIMCl), with no significant alteration observed in the hydrogen bond length within the anion-cation interaction. These results indicate the potential applicability of the new product as a substitute for AMIMCl.

Molecular dynamics simulation on the variations in characteristics of aqueous solution with diverse additives: Inspirations for binary ice preparation

Ice slurry, as a novel energy storage medium, possesses the superiority of high energy storage density. The freezing point inhibitors are employed to regulate the supercooling phenomenon of water, while the macroscopic experiments are complicated to elucidate the action mechanism. Consequently, this paper adopts molecular dynamic simulation method to investigate the mean square displacement, radial distribution function, hydrogen bonds types, hydrogen bonds number and length of water at various concentrations of ethanol, NaCl, and SiO2 additives. The results indicate that the average number of hydrogen bonds of the system composed with 600 pure water molecules is 1127.24, and the average length of hydrogen bonds is 2.33 Å. Moreover, the addition of alcoholics and chlorides inhibits the hydrogen bonds between water and water molecules, and promotes the generation of hydrogen bonds, thus weakening the diffusion motion of water molecules. Whereas, it is observed that the addition of nanoparticles leads to agglomeration in pure water system, resulting an increase in the viscosity and a decrease in the diffusion rate of the system. The proposed microscopic model can effectively depict the potential interaction mechanisms of additives and water, which is contributing to develop effective freezing point inhibitors and improve the energy utilization efficiency.

Induced π–complexation properties of smectites impregnated by Ni, Cu and Ag transition metals: The highly efficient styrene uptake

Two natural smectite minerals (montmorillonite and beidellite) differing in structural charge location were impregnated with varying amounts of transition metals: Ni(II), Cu(I) or Ag(I). The modification aimed to increase the affinity of the minerals towards styrene vapors. The structure, texture, chemical composition and surface chemistry of the materials were studied by XRD, FTIR, Raman, N2 adsorption/desorption, XRF and XPS. The experiments examined the influence of the starting smectite and the type of introduced metal on styrene adsorption efficiency. The styrene uptake mechanisms were investigated through solid state analysis and supported by DFT calculations. The study demonstrated that the small content of introduced metals (<2% wt.) substantially increased styrene uptake (∼200–350% wt.) surpassing values reported for surfactant-intercalated smectites (∼40–80% wt.) and activated carbons (∼30% wt.). This enhancement was attributed to the π-complexation between dispersed d-block metals and π-electron-rich styrene molecules, subsequently leading to polystyrene formation. The DFT calculations were consistent with experimental findings, indicating a higher affinity of the raw beidellite towards styrene than the raw montmorillonite connected to the charge location. Moreover, the observed trends in calculated adsorption energies and lengths of weak hydrogen bonds allowed to explain a significant adsorption increase observed for the Ni- and Cu-impregnated montmorillonite-based materials.

The Temperature Dependence of Hydrogen Bonds Is More Uniform in Stable Proteins: An Analysis of NMR h3JNC' Couplings in Four Different Protein Structures.

Long-range HNCO NMR spectra for proteins show crosspeaks due to 1JNC', 2JNC', 3JNCγ, and h3JNC' couplings. The h3JNC' couplings are transmitted through hydrogen bonds and their sizes are correlated to hydrogen bond lengths. We collected long-range HNCO data at a series of temperatures for four protein structures. P22i and CUS-3i are six-stranded beta-barrel I-domains from phages P22 and CUS-3 that share less than 40% sequence identity. The cis and trans states of the C-terminal domain from pore-forming toxin hemolysin ΙΙ (HlyIIC) arise from the isomerization of a single G404-P405 peptide bond. For P22i and CUS-3i, hydrogen bonds detected by NMR agree with those observed in the corresponding domains from cryoEM structures of the two phages. Hydrogen bond lengths derived from the h3JNC' couplings, however, are poorly conserved between the distantly related CUS-3i and P22i domains and show differences even between the closely related cis and trans state structures of HlyIIC. This is consistent with hydrogen bond lengths being determined by local differences in structure rather than the overall folding topology. With increasing temperature, hydrogen bonds typically show an apparent increase in length that has been attributed to protein thermal expansion. Some hydrogen bonds are invariant with temperature, however, while others show apparent decreases in length, suggesting they become stabilized with increasing temperature. Considering the data for the three proteins in this study and previously published data for ubiquitin and GB3, lowered protein folding stability and cooperativity corresponds with a larger range of temperature responses for hydrogen bonds. This suggests a partial uncoupling of hydrogen bond energetics from global unfolding cooperativity as protein stability decreases.

New hydrogen-bonded liquid crystal supramolecular systems: role of (+ I)-alkoxy substituents in promoting molecular ordering

Novel H-bonded liquid crystals (HBLCs) are synthesized and examined for their mesomorphic behavior. The HBLCs are prepared with Schiff base proton acceptors containing 8 and 18 carbons in the alkyl chain and the proton donor with 4-substituted benzoic acids. All the compounds exhibit smectic A mesophases, with one of the compounds exhibiting LC properties below 298 K. It is interesting to note that the ethoxy-substituted HBLCs exhibit a wide range of thermal stability. Density functional theory calculations revealed the formation of two hydrogen bonds between the substituted acids and the pyridine ring based on the orientation of the donor and the acceptor moieties. There are no significant changes observed in the hydrogen bond length with the increase in the chain length of the proton acceptor moiety, indicating the dilution of the cores by the longer alkyl chain lengths is compensated with the (+ I) effect of alkoxy substituents. Quantum chemical modeling studies on these molecules revealed the reduction in the HOMO–LUMO energy gap by approximately 0.3 eV for oxy-containing compounds, making them more chemically reactive by donating electrons (+ I) into the aromatic cores. These materials provide a significant breakthrough in designing innovative LC materials. This work is in support of the SDG-9 of the United Nations.Graphical abstract

Effect of methyl substitution on hydrogen bond structure of anthocyanin

AbstractIn nature, hydrogen bonding is a common physical occurrence that has a significant impact on the surroundings of anthocyanins. Water molecules will create hydrogen bonds with anthocyanin molecules in various configurations, but the characteristics of these hydrogen bonds will change. Varied hydrogen bonding characteristics have varied impacts on solvent solutions. This research analyzes the differences in hydrogen bonding qualities caused by different methyl structures, as well as the underlying explanations. In this study, the cyanidin and peonidin structures of anthocyanin molecules were calculated in various stable hydrogen bond configurations using the density functional theory B3LYP/6‐31G(d,p), combined with information from the infrared spectroscopy spectrum, atoms in molecules analysis, interaction energy E, and intermolecular hydrogen bond length. The hydrogen bond structure that is the most stable is determined by analyzing it, as well as the effects of replacing the hydroxyl group with a methyl group and any potential underlying causes. Future anthocyanins research can benefit from the precise theoretical reference that this study can offer.

A comparison of the isostructural [Co(NH3)5NO2]XNO3 and [Co(NH3)5ONO]XNO3, X = Cl- or Br- in relation to nitro-nitrito linkage isomerization and photomechanical effects.

A new photoactive cobalt coordination compound, [Co(NH3)5NO2]BrNO3 (I), was obtained. Its crystal structure was shown to be isostructural with previously known [Co(NH3)5NO2]ClNO3 (II) for which linkage isomerization accompanied with mechanical response of the crystal has been already reported. Single crystals of I are transformed into nitrito isomer [Co(NH3)5ONO]BrNO3 (III) on irradiation with blue light (λ = 465 nm) without being destroyed. The crystal structure of III was also solved using single-crystal X-ray diffraction and compared with previously known [Co(NH3)5ONO]ClNO3 (IV). A detailed comparison of the structures of I, II, III and IV, including unit-cell parameters, the distribution of free space (in particular, reaction cavities around the nitro ligand), the lengths of hydrogen bonds, coordination and Voronoi-Dirichlet polyhedra has been performed. Single-crystal X-ray diffraction data were complemented with IR spectra. The effect of the replacement of Cl- by Br- on the crystal structure and on the nitro-nitrito photoisomerization is discussed.

Fast and sustainable CO2 conversion to propylene carbonate using fluoroalcohol-based bifunctional ionic liquids: Insights from experiments and theoretical simulations

We report on the metal-free and rapid catalytic conversion of carbon dioxide into cyclic carbonates under solventless conditions utilizing novel bifunctional fluoroalcohol-based ionic liquids (FBILs) as catalsyts. In the presence of 2.5 mol% 4-(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl) phenyl trimethylammonium iodide (FBIL-1), under 0.1 MPa and 90 °C, excellent yield of propylene carbonate(>95%) was achieved in 1 h, which significantly shortens the reaction time, compared with the conventional catalysts. DFT calculations reveal that FBILs with fluorine-substituted hydroxyl groups exhibit stronger hydrogen bonding with epoxides compared to ILs lacking fluorine substitutions. The hydrogen bond length for ILF/PO is 1.658 Å, shorter than that for IL/PO (1.813 Å). This characteristic contributes to reducing the activation energy for the ring-opening reaction of epoxides. In the ILF/PO system, the reaction barrier is 88.72 kJ·mol−1, lower than the 101.46 kJ·mol−1 barrier for IL/PO, allowing the former to more rapidly facilitate the fixation of carbon dioxide into cyclic carbonates. Besides high catalytic efficiency, these FBILs have the characteristics of a facile synthesis route and easy post-reaction recovery.

Experimental and Theoretical Study of Madder-Associated Dyestuffs on Silk: Adsorption of Kinetics, Thermodynamics and Molecular Docking

ABSTRACT In this work, dyed samples were self-prepared from two methods including madder dyeing and mordant dyeing by madder combined with Al3+ at different temperatures, and their kinetics and isothermal adsorption were both discussed. Weber–Morris diffusion model and Freundlich model were found to be more suitable in dyeing for kinetics and thermodynamics. Through SEM, FTIR and fastness tests, the dyeing performances were displayed and the possible structure between madder dyes and the complex with Al3+ were illustrated. By molecular docking, madder dyes showed combination with glutamic acid predominantly. After introducing metal ion, the shortage of hydrogen bonds length was observed. It was initially employed to elucidate the potential binding modes between dyes and proteinaceous fibers. Overall, through experimental dyeing and curve fitting, this study provided insights into the dyeing mechanism of madder-associated dyestuffs on silk. Moreover, molecular docking elucidated the dyeing mechanism further, highlighting that the presence of metal ion enhances the firmness of the staining. The elucidation of dyeing mechanism not only provided valuable theoretical support for color restoration but also shed light on the practically modify of methods in obtaining ideal color. These results could serve as inspiration for conservators to maintain the vibrancy and longevity of dyed silks.

Molecular structure elucidation -Quantum computational approach, Solvent impact analysis, topological investigation and Molecular docking of N -[2-(7-methoxynaphthalen- 1 -yl) ethyl] acetamide

N-[2-(7-methoxynaphthalen-1-yl) ethyl] acetamide (AGL), a potentially antidepressant chemical molecule, was examined through quantum computational investigations and assessed using theoretical DFT analysis. The different functional groups are identified using FT-IR analysis and these results are contrasted against the simulated spectra. The modes of oscillations were analysed theoretically. The HOMO-LUMO band gap energy was determined for both gaseous and solvent phases (water, methanol, ethanol, and DMSO). Molecular Electrostatic Potential predictions are done to analyse the electrophilic and nucleophilic centres. UV–Vis spectra is performed for the title compound in various solvent. Fukui function, Mulliken charges, ELF, LOL, and RDG were also analysed theoretically. Additionally, molecular docking studies also explored, hydrogen bond length and binding energy were determined. The bioactivity of the compound is recognised by these present studies.

Computational insights into KRAS G12C inhibition: exploring possible repurposing of Azacitidine and Ribavirin

Kirsten rat sarcoma (KRAS) stands out as the most prevalent mutated oncogene, playing a crucial role in the initiation and progression of various cancer types, including colorectal, lung and pancreatic cancer. The oncogenic modifications of KRAS are intricately linked to tumor development and are identified in 22% of cancer patients. This has spurred the necessity to explore inhibition mechanisms, with the aim of investigating and repurposing existing drugs for diagnosing cancers dependent on KRAS G12C In this investigation, 26 nucleoside-based drugs were collected from literature to assess their effectiveness against KRAS G12C. The study incorporates in-silico molecular simulations and molecular docking examinations of these nucleoside-derived drugs with the KRAS G12C protein using Protein Data Bank (PDB) ID: 5V71. The docking outcomes indicated that two drugs, Azacitidine and Ribavirin, exhibited substantial binding affinities of −8.7 and −8.3 kcal/mol, respectively. These drugs demonstrated stability in binding to the active site of the protein during simulation studies. Root mean square deviation (RMSD) analyses indicated that the complexes closely adhered to an equilibrium RMSD value ranging from 0.17 to 0.2 nm. Additionally, % occupancies, bond angles and the length of hydrogen bonds were calculated. These findings suggest that Azacitidine and Ribavirin may potentially serve as candidates for repurposing in individuals with KRAS-dependent cancers. Communicated by Ramaswamy H. Sarma

Quantification of hydrogen bond energy based on equations using spectroscopic, structural, QTAIM-based, and NBO-based descriptors which calibrated by the molecular tailoring approach

ContextHydrogen bonds critically influence the structure and properties of both organic molecules and biomolecules, as well as supramolecular assemblies. For this reason, the development and elaboration of methods for quantitative assessment of hydrogen bond energy is an urgent challenge. In this study, using a large series of hydroxycarbonyl aliphatic compounds with the O‒H···O = C intramolecular hydrogen bond, a bank of hydrogen bond descriptors was created, including spectroscopic, structural, QTAIM-based, and NBO-based parameters. It was shown that the O‒H vibration frequency, OH chemical shift as the spectroscopic descriptors, the O···H hydrogen bond length, O···O distance, and O‒H covalent bond length as the structural descriptors, the electron density and its Laplacian, electron potential energy density in the hydrogen bond critical point, the electron density at the ring critical point as the QTAIM-based descriptors change in a correlated manner. The same correlation is found in change of the charge transfer energy through a hydrogen bond, the occupancy of the O‒H bond antibonding orbital, the Wiberg indices of the O···H hydrogen bond, and the O‒H covalent bond, as well as the polarization of the O‒H bond, which are the NBO-based descriptors. It was also recognized that the specified descriptors from the spectroscopic, structural, QTAIM-based, and NBO-based categories are functionally related to the values of intramolecular hydrogen bond energy, quantified via the molecular tailoring approach. This allowed one to obtain a system of equations for quantitative estimation of intramolecular hydrogen bond energy based on the spectroscopic, structural, QTAIM, and NBO descriptors, which makes such quantification more dependable and reliable.MethodsTo obtain the spectroscopic descriptors, the vibrational spectra and shielding constants were calculated using the GIAO method. Structural descriptors were obtained for the equilibrium geometry of molecules, calculated at the MP2(FC)/6–311 + + (2d,2p) level using the Gaussian 09 program. The QTAIM-based descriptors were calculated using the AIMAll program within the framework of the quantum theory “Atoms in Molecules.” The NBO-based descriptors were calculated using the NBO 3.1 program implemented into Gaussian 09. To quantify the energy of intramolecular hydrogen bonds, molecular fragmentation was used within the molecular tailoring approach.

Spectroscopic probing of ultraviolet-induced degradation in elastomeric polyurea

Aromatic polyurea has garnered assiduous research due to its excellent impact, shock, abrasion, moisture, and chemical resistance properties. Polyurea can be used in protective coating and impact mitigation applications but is inevitably exposed to harsh deployment conditions such as extended ultraviolet (UV) radiation. Fourier Transform Infrared (FTIR) spectroscopy, Terahertz-time domain spectroscopy (THz-TDS), and Excitation-Emission Matrix spectroscopy (EEMS) deciphered the effects of UV radiation on radiated polyurea samples under ambient and nitrogen-rich conditions. Samples were radiated continuously for up to 15 weeks in increments of 3 weeks. Comprehensive FTIR analyses revealed a monotonic increase in disordered hydrogen bonding as a function of exposure duration in an ambient environment. Otherwise, marginal changes were observed in UV-radiated samples under nitrogen. The hydrogen bond length exhibited significant variations in the former compared to their nitrogen atmosphere counterparts. The results infer the nitrogen shielding effect, protecting polyurea from the photodegradation and photo-oxidation observed in samples radiated under the ambient atmosphere. THz-TDS spectra affirmed the FTIR results by probing changes in the complex refractive index. Terahertz spectral peaks associated with torsional vibrations of intermolecular hydrogen bonds in polyurea were notably correlated with increased exposure duration in the ambient atmosphere. Changes in the complex index as a function of exposure duration under nitrogen are minimal. The excitation-emission spectra of polyurea samples reveal a strong fluorescent behavior in 9-week and 12-week ambient-exposed polyurea due to cluster-triggered emission mechanisms. The results synthesized based on three different spectroscopy techniques paint a holistic portrait of the adverse effects of extended ultraviolet radiation of macromolecules deployed in harsh environmental conditions.

Nonequilibrium Ab Initio Molecular Dynamics Simulation of Water Splitting at Fe2O3-Hematite/Water Interfaces in an External Electric Field.

In the exploration of the optimal material for achieving the photoelectrochemical dissociation of water into hydrogen, hematite (α-Fe2O3) emerges as a highly promising candidate for proof-of-concept demonstrations. Recent studies suggest that the concurrent application of external electric fields could enhance the photoelectrochemical (PEC) process. To delve into this, we conducted nonequilibrium ab initio molecular dynamics (NE-AIMD) simulations in this study, focusing on hematite-water interfaces at room temperature under progressively stronger electric fields. Our findings reveal intriguing evidence of water molecule adsorption and dissociation, as evidenced by an analysis of the structural properties of the hydrated layered surface of the hematite-water interface. Additionally, we scrutinized intermolecular structures using radial distribution functions (RDFs) to explore the interaction between the hematite slab and water. Notably, the presence of a Grotthuss hopping mechanism became apparent as the electric field strength increased. A comprehensive discussion based on intramolecular geometry highlighted aspects such as hydrogen-bond lengths, H-bond angles, average H-bond numbers, and the observed correlation existing among the hydrogen-bond strength, bond-dissociation energy, and H-bond lifetime. Furthermore, we assessed the impact of electric fields on the librational, bending, and stretching modes of hydrogen atoms in water by calculating the vibrational density of states (VDOS). This analysis revealed distinct field effects for the three characteristic band modes, both in the bulk region and at the hematite-water interface. We also evaluated the charge density of active elements at the aqueous hematite surface, delving into field-induced electronic charge-density variations through the Hirshfeld charge density analysis of atomic elements. Throughout this work, we drew clear distinctions between parallel and antiparallel field alignments at the hematite-water interface, aiming to elucidate crucial differences in local behavior for each surface direction of the hematite-water interface.

New theoretical perspective for easy evaluation of the antioxidant properties of typical flavonoids

To intensively investigate the antioxidant property of flavonoids and their different phenolic hydroxyl groups, we selected six types of typical flavonoids and carried out experimental analysis and quantum chemical calculations. By calculating the Mulliken charges, frontier molecular orbitals, molecular dipole moments, and interaction model hydrogen bond lengths of the compounds, the theoretical analysis results were compared with the free radical scavenging assays. Results show that the three flavonoids with different numbers of hydroxyl groups on the B ring are ranked in antioxidant activity as myricetin > quercetin > kaempferol. The glycoside linked in the C ring has a great effect on bioavailability, and the antioxidant activity is ranked as quercetin > isoquercetin > rutin. Besides, the results of the novel interaction model calculations show that quercetin with an meta-hydroxy group on the B ring structure has stronger antioxidant capacity than morin with an ortho-hydroxy group. The theoretical evaluation method established in this work is expected to provide new ideas and references for the evaluation of antioxidant properties of natural active substances from the electronic structure perspective.

Excited state proton transfer mechanism of a thiazolo [5,4-d] thiazole derivative in different solvents

In this paper, the excited state proton transfer mechanism of a thiazolo [5,4-d] thiazole derivative, 4-tert-butyl-2-(5-(5-tert-butyl-2-methoxyphenyl) thiazolo [5,4-d] thiazol-2-yl) phenol (MTTH), has been investigated in different polar solvents by using DFT and TDDFT methods. The hydrogen bond lengths, bond angles, and corresponding infrared vibrational frequencies of MTTH in three different polar solvents were compared, and the analytical results showed that the intramolecular hydrogen bonding of MTTH was enhanced in all S1 states. In addition, the simulated absorption and emission spectra values of MTTH are in good agreement with the experimental data, which further proves the rationality of the calculation method. Meanwhile, the electron density rearrangement between the proton acceptor and donor was found by analyzing the frontline molecular orbitals of the MTTH, which is favorable for the excited state proton transfer process. Finally, the potential energy curves of MTTH in three different solvents were calculated, and the results indicated that the weakly polar solvents were more favorable for the excited state intramolecular proton transfer of MTTH.

Design, synthesis, and antiviral activities of myricetin derivatives containing phenoxypyridine

A series of myricetin derivatives containing phenoxypyridine structure were designed and synthesized on the basis of the natural product myricitrin, which were structurally characterized on NMR and HRMS. The results of antiviral activity tests showed that some of the target compounds exhibited better inhibitory effects. Among them, B19 and B21 showed better curative activity with EC50 values of 195.67 and 173.64 μg/mL, respectively, which were superior to that of the control agent ningnanmycin(NNM) (238.30 μg/mL). B21 showed better protective activity with EC50 value of 236.37 μg/mL, which was better than that of the control agent NNM (269.89 μg/mL). The results of microcalorimetry showed that B1, B19 and B21 had good binding affinity with tobacco mosaic virus capsid protein (TMV-CP), and the Kd values were 0.059, 0.093 and 0.069 μM, which was higher than that of NNM (Kd = 2.78 μM). The molecular docking results showed that the hydrogen bond lengths between B1, B21 and the key amino acid residues of TMV-CP were shorter and with more tightly bound than those of NNM. In B21-treated tobacco leaves, chlorophyll content and superoxide dismutase (SOD) activity were significantly elevated, indicating that B21 can participate in regulating plant photosynthesis as well as defense enzymes and inducing plants to improve disease resistance.

Implementation of Phase Transitions in Rb3H(SO4)2 under K Substitution

A series of solid acid compounds, representing the large family MmHn(AO4)(m + n)/2·yH2O (where M = K, Rb, Cs, NH4; AO4 = SO4, SeO4, HPO4, HAsO4), is characterized by high values of own proton conductivity, which arises as a result of a phase transition through the formation of a dynamically disordered hydrogen bond network. Such superprotonic phase transitions are observed, however, not for all compounds of the family and Rb3H(SO4)2 is one of them. The occurrence of superprotonic phase transitions has been experimentally demonstrated in the (KxRb1−x)3H(SO4)2 solid solutions through cation substitution. The high-temperature phases are unstable towards decomposition reaction, and their temperature range of existence is about 1–7 °C. The implementation of superprotonic transitions is discussed in terms of hydrogen bond lengths.

Intermolecular charge fluxes and terahertz spectral features of liquid methanol

The behavior of electrons that is relevant to the THz spectral features of liquid methanol is examined theoretically through analyses of the dipole derivatives and the electron density derivatives with respect to the molecular translations and rotations of hydrogen-bonded methanol. It is shown that the hydrogen-bond-induced components of these derivatives are reasonably well interpreted or modeled by intermolecular charge fluxes through hydrogen bonds, which represent the modulations of the extent of hydrogen-bond-induced intermolecular charge transfer occurring upon fluctuations of hydrogen-bond lengths. Combining this model with classical molecular dynamics, spectral simulations in the 0–1000 cm−1 region are carried out, resulting in reasonably good agreement with the observed overall spectral features. The spectral simulations are based on two different formulas that are suitable for different ways of spectral decomposition. The factors with regard to intensity generation and molecular motion that are important for each element of the spectral features are discussed.

Assessment of the performance of mesityl oxide extraction from water with n-alkanols: A study on liquid–liquid equilibrium, thermodynamic modeling, and simulation analysis

Mesityl oxide (MO) is a crucial organic synthesis intermediate and a popular high boiling point solvent. However, during its production process, wastewater containing MO is easily generated. To recover MO from wastewater, four alkanols with different carbon chain lengths (C6-C9) were chosen as extractants for the separation of MO from water. Liquid-liquid equilibrium (LLE) data for the ternary mixture of extractants + MO + water was experimentally measured at 303.2 K and 101.3 kPa. The separation factor (S) and distribution coefficient (D) were used to evaluate the extraction performance of the four extractants in separating MO from water. The results showed that 1-nonanol exhibited higher S and D values compared to other extractants, indicating its suitability as an effective extractant. The NRTL and UNIQUAC models were used to correlate the experimental data and determine the regression parameters. According to the mixing surface analysis based on the Gibbs energy topology, the binary interaction parameters are found to be consistent with the measured data. The UNIFAC model was used for predicting LLE data and comparing the results with the experimental data. The root mean square deviation (RMSD) was lower than 0.0077, 0.0075, and 0.0211 in these three models, respectively. In addition, differences in extractant extraction effects were analyzed by intermolecular interactions (σ-Profile, interaction energy, and hydrogen bond length).