Compounds In Aqueous Solution Research Articles

Radiation-Initiated Dehalogenation of Organofluorine Compounds in Aqueous Solutions

Radiation-Initiated Dehalogenation of Organofluorine Compounds in Aqueous Solutions

Chemical-free fabrication of carbon fiber aerogels from egg boxes for the removal of pharmaceutically active compounds in aqueous solution

The presence of pharmaceuticals and personal care products (PPCPs) in aquatic environments extremely concerns to human health and the ecosystem; thus, their removal is essential. This work produced carbon fiber aerogels from egg box waste using a chemical-free fabrication process. The pyrolyzed egg box aerogel (PEBA) exhibited three-dimensional interconnected carbon nanofibers with high surface area and pore volume. The adsorption capacity and removal efficiency of four PPCPs, namely, diclofenac (DIC), caffeine (CF), tetracycline (TC), and ciprofloxacin (CIP), from water were high and comparable to other carbon-based adsorbents, and the adsorption time was much faster (within 20 min). The Redlich-Peterson and the pseudo-second-order models were the best-fitted isotherm and kinetic models, respectively, which imply multilayer adsorption at high concentrations and the chemisorption process. Furthermore, mechanisms responsible for the adsorption of all PPCPs were elucidated. PEBA was applied in the fixed-bed column experiment to mimic the continuous adsorption process. In addition, PEBA was recyclable after low-temperature heat treatment. The adsorption capacity (8.1 mg/g) and removal efficiency (94.03 %) for TC was still high after three cycles. Metabolomics analysis revealed that no secondary pollution is released into water after thermal treatment. Therefore, PEBA has the potential as an efficient adsorbent for removing PPCPs from water.

The Lantana camara L. stem biomass as an inexpensive and efficient biosorbent for the adsorptive removal of malachite green from aquatic environments: kinetics, equilibrium and thermodynamic studies

Plant biomass is one of the available and economic biomaterials used to remove environmental pollutants. The presence of colored compounds in aqueous solutions is one of the problems that can be solved by biological methods. Herein, the efficiency of available and inexpensive biomass obtained from Lantana camara L. stem for cationic dye uptake has been evaluated. The effect of operational factors, including dosage of L. camara L. stem biomass (LSB), pH of the solution, initial concentration of malachite green (MG), and residence time on the optimal conditions of analyte uptake was studied. The experimental data of adsorption studies fit with P-S-O kinetic () and L.I.M (), indicating MG dye adsorption onto LSB occurred in monolayers due to its chemical affinity. The maximum uptake capacity of LSB for the removal of MG dye was 100 mg g−1. Thermodynamic parameters, including (from −2.13 to −2.469 ), (+2.916 ), and (+16.934 ) suggested that the adsorption process was endothermic and spontaneous. The results revealed that LSB considerably has potential for adsorptive removal of cationic dyes such as, MG from aquatic environments.

Radiation-Initiated Dehalogenation of Organofluorine Compounds in Aqueous Solutions

The γ-radiolysis of 2-fluoroethanol-1, 2,2,2-trifluoroethanol-1, 3-fluoropropanol-1, and 4,4,4- trif luorobutanol-1 in aqueous solutions in an inert atmosphere or in the presence of oxygen has been studied. It has been found that the dehalogenation of hydroxyl-containing organic compounds is induced by •ОН and Н• radicals rather than hydrated electrons. The carbon-centered α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH are def luorinated much more efficiently than α-fluoroalkyl radicals, both vicinal (F–•CHCH2OH) and nonvicinal (F–•CHCH2CH2OH). In the absence of oxygen, α-fluoroalkyl radicalseliminate fluoride ions by the mechanism of nucleophilic substitution, and this process is enhanced in the presence of alkali. In an oxygenated medium, the dehalogenation of α-fluoroalkyl radicals occurs via the addition of oxygen molecules to them and the subsequent disproportionation of resulting peroxyl radicals. The dehalogenation of the α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH is inhibited by oxygen through their oxidation.

New Model to Predict Infinite Dilution Activity Coefficients Based on (∂p/∂x) T,x → 0.

Accurate prediction of infinite dilution activity coefficient (γ∞) is essential for the calculation of phase equilibria, solubility, and related properties in molecular thermodynamics. Here, we propose a new model to accurately predict the value of γ∞. It is applicable to calculate γ∞ for compounds in aqueous solution at different temperatures. The model is based on the relationship of (∂p/∂x) T,x→0 with γ∞ and temperature at low pressure. First, we introduce the new idea of using the group contribution method to estimate (∂p/∂x) T,x→0 and then obtain the activity coefficient of a solute at infinite dilution in water based on the relationship between (∂p/∂x) T,x→0 and γ∞. The accuracy of this model is verified using experimental data from 46 systems and more than 450 data points. The result shows that the total average relative deviation of the predicted values from the experimental values for training data is 4.73%. Besides, we test the applicability of the model using solutes that are not part of the training data set. The result shows that the model is satisfactory for the prediction of testing data. Compared with other models, the results prove that the developed model outperforms the UNIFAC model, the modified UNIFAC model, and previous predictive models for aqueous systems. The final equation with only simple arithmetic is more easily applied in engineering practices.

Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit

Unveiling the structural evolution of single-crystalline compounds based on certain building units may help greatly in guiding the design of complex structures. Herein, a series of praseodymium antimony oxohalide crystals have been isolated under solvothermal conditions via adjusting the solvents used, that is, [HN(CH2CH3)3][FeII(2,2'-bpy)3][Pr4Sb12O18Cl15]·EtOH (1) (2,2'-bpy = 2,2'-bipyridine), [HN(CH2CH3)3][FeII(2,2'-bpy)3]2[Pr4Sb12O18Cl14)2Cl]·N(CH2CH3)3·2H2O (2), and (H3O)[Pr4Sb12O18Cl12.5(TEOA)0.5]·2.5EtOH (3) (TEOA = mono-deprotonated triethanolamine anion). Single-crystal X-ray diffraction analysis revealed that all the three structures feature an anionic zig-zag chain of [Pr4Sb12O18Cl15-x]n as the tertiary building unit (TBU), which is formed by interconnections of praseodymium antimony oxochloride clusters (denoted as {Pr4Sb12}) as secondary building units. Interestingly, different arrangements or linkages of chain-like TBUs result in one-dimensional, two-dimensional layered, and three-dimensional structures of 1, 2, and 3, respectively, thus demonstrating clearly the structural evolution of metal oxohalide crystals. The title compounds have been characterized by elemental analysis, powder X-ray diffraction, thermogravimetric analysis, and UV-Vis spectroscopy, and the photodegradation for methyl blue in an aqueous solution of compound 1 has been preliminarily studied. This work offers a way to deeply understand the assembly process of intricate lanthanide-antimony(III) oxohalide structures at the atomic level.

A fast and efficient method for the analysis of α-dicarbonyl compounds in aqueous solutions: Development and application

Among the highly oxygenated species formed in situ in the atmosphere, α-dicarbonyl compounds are the most reactive species, thus contributing to the formation of secondary organic aerosols that affect both air quality and climate. They are ubiquitous in the atmosphere and are easily transferred to the atmospheric aqueous phase due to their high solubility. In addition, α-dicarbonyl compounds are toxic compounds found in food in biochemistry studies as they can be produced endogenously through various pathways and exogenously through the Maillard reaction. In this work, we take advantage of the high reactivity of α-dicarbonyl compounds in alkaline solutions (intramolecular Cannizzaro reaction) to develop an analytical method based on high performance ion chromatography. This fast and efficient method is suitable for glyoxal, methylglyoxal and phenylglyoxal which are detected as glycolate, lactate and mandelate anions respectively, with 100% conversion at pH > 12 and room temperature for exposure times to hydroxide ranging from 5 min to 4 h. Diacetyl is detected as 2,4-dihydroxy-2,4-dimethyl-5-oxohexanoate due to a base-catalysed aldol reaction that occurs before the Cannizzaro reaction. The analytical method is successfully applied to monitor glyoxal consumption during aqueous phase HO∙-oxidation, an atmospherically relevant reaction using concentrations that can be observed in fog and cloud water. The method also reveals potential analytical artifacts that can occur in the use of ion chromatography for α-hydroxy carboxylates measurements in complex matrices due to α-dicarbonyl conversion during the analysis time. An estimation of the artifact is given for each of the studied α-hydroxy carboxylates. Other polyfunctional and pH-sensitive compounds that are potentially present in environmental samples (such as nitrooxycarbonyls) can also be converted into α-hydroxy carboxylates and/or nitrite ions within the HPIC run. This shows the need for complementary analytical measurements when complex matrices are studied.

Synthesis of Sb2S3 nanosphere layer by chemical bath deposition for the photocatalytic degradation of methylene blue dye.

An antimony tri-sulfide Sb2S3 nanosphere photocatalyst was effectively deposited utilizing sodium thiosulfate and antimony chloride as the starting precursors in a chemical bath deposition process. This approach is appropriate for the large-area depositions of Sb2S3 at low deposition temperatures without the sulfurization process since it is based on the hydrolytic decomposition of starting compounds in aqueous solution. X-ray diffraction patterns and Raman spectroscopy analysis revealed the formation of amorphous Sb2S3 layers. The scanning electron microscopy images revealed that the deposited Sb2S3 has integrated small nanospheres into sub-microspheres with a significant surface area, resulting in increased photocatalytic activity. The optical direct bandgap of the Sb2S3 layer was estimated to be about 2.53 eV, making amorphous Sb2S3 appropriate for the photodegradation of organic pollutants in the presence of solar light. The possibility of using the prepared Sb2S3 layer in the photodegradation of methylene blue aqueous solutions was investigated. The degradation of methylene blue dye was performed to evaluate the photocatalytic property of Sb2S3 under visible light. The amorphous Sb2S3 exhibited photocatalytic activity for the decolorization of methylene blue solution under visible light. The mechanism for the photocatalytic degradation of methylene blue has been proposed. Our results suggest that the amorphous Sb2S3 nanospheres are valuable material for addressing environmental remediation issues.

The high fluorescence sensitivity property and quenching mechanism of one-dimensional Cd-HCIA-1 sensor for nitrobenzene.

The sensing of nitroaromatic compounds in aqueous solution is closely related to environmental sustainability and human health. In this study, a novel Cd(II) coordination polymer (Cd-HCIA-1) was designed and prepared, and its crystal structure, luminescence performance, detection of nitro pollutants in water, and fluorescence quenching mechanisms were studied. Cd-HCIA-1 exhibited a one-dimensional ladder-like chain based on a T-shape ligand of 5-((4-carboxybenzyl) oxy) isophthalic acid (5-H3CIA). The H-bonds and π-π stacking interactions were then used to construct the supramolecular skeleton in common. Luminescence studies revealed that Cd-HCIA-1 can detect nitrobenzene (NB) in aqueous solution with high sensitivity and selectivity, and the limit of detection was 3.03 × 10-9 mol L-1. The fluorescence quenching mechanism of the photo-induced electron transfer for NB by Cd-HCIA-1 was obtained through an investigation of the pore structure, density of states, excitation energy, orbital interactions, hole-electron analysis, charge transfer, and electron transfer spectra by using density functional theory (DFT) and time-dependent DFT methods. NB was absorbed in the pore, π-π stacking increased the orbital overlap, and the LUMO was mainly composed of NB fragments. The charge transfer between ligands was blocked, resulting in fluorescence quenching. This study on fluorescence quenching mechanisms can be used to develop efficient explosive sensors.

A Natural Monoterpene Enol for Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplets for Determination of Benzophenone Compounds in Water Samples

In the current study, an effective and simple procedure of extraction for the four benzophenone compounds from water samples was achieved by dispersive liquid–liquid microextraction (DLLME) based on the solidification of floating organic droplets (SFO) with a natural monoterpene enol as the extractant. As a natural, high solidification point, inexpensive, and environmentally friendly hydrophobic solvent, α−terpineol was selected firstly as an extractant for DLLME and could be collected and transferred easily after extraction by solidification at a lower temperature. Several main parameters closely related to extraction efficiencies, such as volume of extractant, extraction time, pH and salt concentration of the sample solution, temperature, and time of the solidification process, were investigated in detail. The results showed that the established method had good extraction performance for benzophenone compounds with enrichment factors in the range of 29–47. Furthermore, the linearities were over the range of 2–2000 µg/L, and the limits of detection were 0.12–0.53 µg/L for four benzophenone compounds. The recoveries ranged from 80.2% to 108.4%, with RSDs (intra- and inter-assay) less than 8.5%. At last, the method applicability was investigated by the determination of the benzophenone compounds in aqueous solutions, and satisfactory recoveries (83.0–107.0%) were acquired. Taken together, α−terpineol, a natural monoterpene enol, was first used as an extractant of DLLME-SFO, which provided an alternative method with simplicity and rapidity for the determination of benzophenone compounds in aqueous samples.

Impact of [formula omitted] on the thermophysical and FTIR properties of protein model compounds in aqueous solutions

Ionic liquids (ILs) have gained popularity in recent years due to their wide range of applications in chemical synthesis. They can be used in advancing technologies such as protein solubilization, increased protein activity, biocatalysis replication, and enzyme stability. Because of this, ILs can shed light on the ability of proteins to maintain stability. The present paper outlines the impact of IL on the thermophysical and FTIR properties of specific protein model compounds in aqueous solutions. Thus, densities ρand viscosities ηof some protein model compounds in aqueous solutions of ionic liquid, 1-butyl-3-methylimidazolium chloride, BMImCl, at various temperatures have been carried out at atmospheric pressure. These studies are aimed at gaining new insights into the ability of biomolecules to interact with IL, which is critical for understanding protein behaviour in solutions.Various parameters such as apparent molar volumes (V∅), partial molar volumes (V2O), viscosity B-coefficients, temperature coefficients (dB/dT), transfer parameters, i.e.,ΔtrV2o and ΔtrB, interaction parameters,YAB and YABB, hydration number i.e.nH and Nh, partial molar expansibilities ∂V2O/∂TP, their second-order derivatives ∂2V2O/∂T2P, and isobaric thermal expansion coefficients (αIL) have been calculated from density and viscosity data. In aqueous BMImCl, partial molar expansibilities and temperature coefficients are used to predict the structure maker/breaker behaviour of amino acids. Volume transfer values indicate the dominance of ionic-hydrophilic interactions. Thermodynamic parameters suggest that the formation of the transition state is less favoured in the presence of BMImCl solutions. Also, the effects of the hydrophilic ionic liquid, 1-butyl-3-methylimidazolium chloride,BMImCl on the ion-hydrophilic, hydrophobic-hydrophilic, and hydrophobic-hydrophobic interactions present in ternary systems, as well as the effects of temperature and alkyl chain length, have been discussed. FTIR spectra were measured to analyze the structural changes that occurred in the system. The current work provides some important fundamental experimental data and theoretical support for further exploring the interactions of various amino acids with ILs.

Selective Photocatalytic Transformation of Lignin to Aromatic Chemicals by Crystalline Carbon Nitride in Water–Acetonitrile Solutions

The photocatalytic conversion of lignin to aromatic compounds in aqueous solutions is a promising approach. We herein report a crystalline carbon nitride prepared by high-temperature thermal polymerization and alkali-metal molten salt treatment, which was then applied in the selective conversion of lignin to aromatic compounds. The results showed that the tri-s-tri-C3N4 presented a relatively high activity and selectivity for the conversion of lignin in aqueous solutions. In a 95% water-acetonitrile solution, it achieved a relatively high conversation rate of lignin, reaching 62.00%, and the selectivity of the C-C bond cleavage was high, at 86.8%. The characterization results obtained by TEM, UV-vis/DRS, PL, and transient photocurrent response showed that the ultra-high activity of tri-s-tri-C3N4 was mainly due to the improvements in crystallinity and light absorption. Mechanism studies showed that the dispersion of the catalyst and the combination of lignin and catalyst in aqueous solvents with different acetonitrile ratios were the main factors affecting lignin conversion. As the water content in the solutions increased, the primary active sites were converted from h+ to ·O2-. This study revealed the interactions between lignin, photocatalysts, and reaction solutions, providing a theoretical basis for the photocatalytic conversion of lignin in aqueous solutions.

Preliminary Free Energy Map of Prebiotic Compounds Formed from CO2, H2 and H2S.

What kinds of CHOS compounds might be formed in a prebiotic milieu by reducing CO2 in the presence of H2 and H2S? How might the presence of sulfur influence the chemical composition of the mixture? We explore these questions by using first-principles quantum chemistry to calculate the free energies of CHOS compounds in aqueous solution, by first generating a thermodynamic map of one- and two-carbon species. We find that while thiols are thermodynamically favored, thioesters, thioacids, and thiones are less favorable than their non-sulfur counterparts. We then focus on the key role played by mercaptoacetaldehyde in sulfur analogs of the autocatalytic formose reaction, whereby the thiol group introduces asymmetry and potential thermodynamic selectivity of some compounds over others.

Hydrophobic microporous extraction on polyurethane sponges for convenient and sensitive analysis of organic molecules in water.

Various solvent supports have been developed to overcome solvent instability during liquid-phase microextraction. The hydrophobic polyurethane sponge (PS) possesses numerous cross-linked internal microchannels and terminal micropores that can facilitate steady solvent storage capacity, high extraction efficiency, extractant loading, and recycling convenience. In this study, an easy, convenient, and efficient PS-supported liquid-phase microextraction (PS-LPME) coupled with gas chromatography-mass spectrometry (GC-MS) method was developed for the trace analysis of different organic compounds in aqueous solutions. Different extraction solvents, PS dosages, stirring speeds, and extraction times were first investigated by extracting eight polycyclic aromatic hydrocarbons (PAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene), and then applied for the analysis of triazines, amides, chloroacetamides, and organophosphorus compounds. High enrichment factors (approximately 208-439) were observed for the monitored PAHs. Good linearities, with determination coefficients (r2 ) greater than 0.9992, were achieved in the concentration range of 0.01-50 μg L-1 . Low limits of detection and quantification were found in the ranges of 0.3-3ng L-1 and 1-10ng L-1 , respectively. At three spiked concentrations (0.1, 1, and 10μg L-1 ), good recoveries were obtained in the range of 91.6-118.5% with intra- and inter-day relative standard deviations of less than 6.4% and 11.7%, respectively. The developed PS-LPME method coupled with GC-MS was successfully applied in the analysis of different organic compounds in aqueous solutions and has shown great convenience and satisfactory enrichment performance in microextraction analysis.

Mechanism for selective binding of aromatic compounds on oxygen-rich graphene nanosheets based on molecule size/polarity matching

Selective binding of organic compounds is the cornerstone of many important industrial and pharmaceutical applications. Here, we achieved highly selective binding of aromatic compounds in aqueous solution and gas phase by oxygen-enriched graphene oxide (GO) nanosheets via a previously unknown mechanism based on size matching and polarity matching. Oxygen-containing functional groups (predominately epoxies and hydroxyls) on the nongraphitized aliphatic carbons of the basal plane of GO formed highly polar regions that encompass graphitic regions slightly larger than the benzene ring. This facilitated size match–based interactions between small apolar compounds and the isolated aromatic region of GO, resulting in high binding selectivity relative to larger apolar compounds. The interactions between the functional group(s) of polar aromatics and the epoxy/hydroxyl groups around the isolated aromatic region of GO enhanced binding selectivity relative to similar-sized apolar aromatics. These findings provide opportunities for precision separations and molecular recognition enabled by size/polarity match–based selectivity.

A Cruciform Petal-like (ZIF-8) with Bactericidal Activity against Foodborne Gram-Positive Bacteria for Antibacterial Food Packaging.

Most antibacterial nanomaterials used in food packaging act by releasing reactive oxygen species (ROS), which cannot efficiently have an inhibitory effect by penetrating the cell wall of Gram-positive Staphylococcus aureus. In this work, we used the cruciform petal-like zeolite imidazole framework-8 (ZIF-8) synthesized in the water phase which can release active Zn compounds in aqueous solution and exert a stronger inhibitory effect on S. aureus. The experimental results demonstrated that the aqueous cruciform petal-like ZIF-8 has the same photocatalytic activity as traditional ZIF-8 and can be applied in photocatalytic bacterial inactivation. The cruciform petal-like ZIF-8 was also shown to release active Zn compounds in aqueous solution with a better antibacterial effect against S. aureus, reaching 95% inactivation efficiency. The antibacterial effect was therefore 70% higher than that of traditional ZIF-8. Based on its excellent antibacterial properties, we loaded petal-like ZIF-8, PDA and PVA onto ordinary fibers to prepare ZIF-8-Film. The results further showed that ZIF-8-Film has a high filtration capacity, which can be used in antibacterial packaging material with the required air permeability. Moreover, ZIF-8-Flim can clean the surface on its own and can maintain a sterile environment. It is different from other disposable materials on the market in that it can be reused and has a self-disinfection function.

Synthesis of a novel ZnO/TiO2-nanorod MXene heterostructured nanophotocatalyst for the removal pharmaceutical ceftriaxone sodium from aqueous solution under simulated sunlight

ZnO nanospherical particles supported TiO2-nanorod MXene heterostructured nanophotocatalyst were synthesized to photodegrade harmful ceftriaxone sodium compound in aqueous solution under simulated solar light irradiation. Under optimum conditions, the prepared nanoheterostructured photocatalyst demonstrated excellent performance in the elimination of ceftriaxone sodium compound with an evaluated efficiency of 99.4%. Initial concentrations, pH solution, catalyst loading, kinetic investigations, optical bandgap, regeneration, and reusability were investigated in consideration of this study. At pH 7.0, the produced ZnO/TiO2-nanorod MXene was successfully activated. It was found that ZnO nanoparticles improved ceftriaxone sodium degradation efficiency on TiO2-MXene by acting as photogenerated transport of the e-/h+, lowering the recombination rate. Under ideal conditions, the maximal absorption capacity was 4.99882 mg/g. Furthermore, the produced ZnO/TiO2-nanorod MXene has a remarkable optical bandgap. The prepared nano-heterostructured photocatalyst conforms well to the pseudo-first order model, with a Chi-square of 0.08899. The ZnO/TiO2-nanorod MXene heterostructured nanophotocatalyst retained its great performance with remarkable durability despite numerous cycles of usage. According to the results, the suggested nanoheterojunction photocatalyst might be used in a water treatment plant to eliminate the danger of pharmaceutical waste in the aqueous medium.

Elucidation of Structure-Activity Relationships in Indolobenzazepine-Derived Ligands and Their Copper(II) Complexes: the Role of Key Structural Components and Insight into the Mechanism of Action.

Indolo[3,2-d][1]benzazepines (paullones), indolo[3,2-d][2]benzazepines, and indolo[2,3-d][2]benzazepines (latonduines) are isomeric scaffolds of current medicinal interest. Herein, we prepared a small library of novel indolo[3,2-d][2]benzazepine-derived ligands HL1–HL4 and copper(II) complexes 1–4. All compounds were characterized by spectroscopic methods (1H and 13C NMR, UV–vis, IR) and electrospray ionization (ESI) mass spectrometry, while complexes 2 and 3, in addition, by X-ray crystallography. Their purity was confirmed by HPLC coupled with high-resolution ESI mass spectrometry and/or elemental analysis. The stability of compounds in aqueous solutions in the presence of DMSO was confirmed by 1H NMR and UV–vis spectroscopy measurements. The compounds revealed high antiproliferative activity in vitro in the breast cancer cell line MDA-MB-231 and hepatocellular carcinoma cell line LM3 in the low micromolar to nanomolar concentration range. Important structure–activity relationships were deduced from the comparison of anticancer activities of HL1–HL4 and 1–4 with those of structurally similar paullone-derived (HL5–HL7 and 5–7) and latonduine-derived scaffolds (HL8–HL11 and 8–11). The high anticancer activity of the lead drug candidate 4 was linked to reactive oxygen species and endoplasmic reticulum stress induction, which were confirmed by fluorescent microscopy and Western blot analysis.

Interaction of trans-tetrachlorodi-m-carboxylates of dirhenium(III) with dipeptides of the glycyl series

The paper reports the methods for the synthesis of new cluster compounds of trans-tetrachlorodi--carboxylates of dirhenium(III) with dipeptides of the glycyl series. The compositions and the structures were determined by electron absorption and IR spectroscopies as well as by elemental analysis for the following newly synthesized compounds: trans-[Re2(H3N+–CH2–СO–NH–CH(COO)–CH2–CH(CH3)–CH3)2Cl42СН3CN]Cl2 (І) and trans-[Re2(H3N+–CH2–СO–NH–CH(COO)–CH2–C6H5)2Cl42СН3CN]Cl2 (ІІ). Analysis of the electronic absorption spectra of the solutions of the synthesized substances showed the presence of a doublet pattern (12500 and 16129 сm–1), which corresponds to the *-electronic transition of the Re–Re quadruple bond characteristic of solutions of trans-tetrachlorodi--carboxylates of dirhenium(III). The appearance of oscillations at 1485 сm–1 for І and 1486 сm–1 for ІІ, characteristic of the s(CO) of the coordinated carboxylate group, was detected on the IR spectra, which indicates the bridging coordination of this group to the Re26+ binuclear fragment. The protonation of the amino group is indicated by the appearance of a wide band of valence oscillations (NH3+) in the range of 3400–3350 сm–1 and deformation oscillations (NH3+) at 1557 сm–1 and 1614 сm–1 for I and II, respectively. The stability of the obtained complex compounds in aqueous solutions was determined. It was shown that the hydrolysis of the synthesized substances takes place in 4–5 days, which is accompanied by a decrease in the pH of the reaction solution.

Diclofenac Ion Hydration: Experimental and Theoretical Search for Anion Pairs.

Self-assembly of organic ions in aqueous solutions is a hot topic at the present time, and substances that are well-soluble in water are usually studied. In this work, aqueous solutions of sodium diclofenac are investigated, which, like most medicinal compounds, is poorly soluble in water. Classical MD modeling of an aqueous solution of diclofenac sodium showed equilibrium between the hydrated anion and the hydrated dimer of the diclofenac anion. The assignment and interpretation of the bands in the UV, NIR, and IR spectra are based on DFT calculations in the discrete-continuum approximation. It has been shown that the combined use of spectroscopic methods in various frequency ranges with classical MD simulations and DFT calculations provides valuable information on the association processes of medical compounds in aqueous solutions. Additionally, such a combined application of experimental and calculation methods allowed us to put forward a hypothesis about the mechanism of the effect of diclofenac sodium in high dilutions on a solution of diclofenac sodium.