Interaction Of Organic Solvents Research Articles

Empirical Model of Solvophobic Interactions in Organic Solvents

AbstractAn empirical model was developed to predict organic solvophobic effects using N‐phenylimide molecular balances functionalized with non‐polar alkyl groups. Solution studies and X‐ray crystallography confirmed intramolecular alkyl‐alkyl interactions in their folded conformers. The structural modularity of the balances allowed systematic variation of alkyl group lengths. Control balances were instrumental in isolating weak organic solvophobic effects by eliminating framework solvent‐solute effects. A 19F NMR label enabled analysis across 46 deuterated and non‐deuterated solvent systems. Linear correlations were observed between organic solvophobic effects and solvent cohesive energy density (ced) as well as changes in solvent‐accessible surface areas (SASA). Using these empirical relationships, a model was constructed to predict organic solvophobic interaction energy per unit area for any organic solvent with known ced values. The predicted interaction energies aligned with recent organic solvophobic measurements and literature values for the hydrophobic effect on non‐polar surfaces confirmed the model‘s accuracy and utility.

Empirical Model of Solvophobic Interactions in Organic Solvents.

An empirical model was developed to predict organic solvophobic effects using N-phenylimide molecular balances functionalized with non-polar alkyl groups. Solution studies and X-ray crystallography confirmed intramolecular alkyl-alkyl interactions in their folded conformers. The structural modularity of the balances allowed systematic variation of alkyl group lengths. Control balances were instrumental in isolating weak organic solvophobic effects by eliminating framework solvent-solute effects. A 19 F NMR label enabled analysis across 46 deuterated and non-deuterated solvent systems. Linear correlations were observed between organic solvophobic effects and solvent cohesive energy density (ced) as well as changes in solvent-accessible surface areas (SASA). Using these empirical relationships, a model was constructed to predict organic solvophobic interaction energy per unit area for any organic solvent with known ced values. The predicted interaction energies aligned with recent organic solvophobic measurements and literature values for the hydrophobic effect on non-polar surfaces confirmed the model's accuracy and utility.

Improvement of the crushing effect of waste printed circuit boards by co-heating swelling with organic solvent

The crushing is a crucial unit operation for recycling waste printed circuit boards. In this study, dimethylacetamide was used to improve the crushing efficiency of waste printed circuit boards. The sectional morphology of the printed circuit boards was observed by scanning electron microscopy after a swelling treatment, the result showed the metal-nonmetal interface appeared noticeable cracks. The mechanical properties of material was measured by dynamometer, the results indicated that the destructive load of treated printed circuit boards was reduced by 115.32 N. The yield and metal grade of the crushed products were determined for each fraction. For the −0.074 mm fraction, the swelling treatment reduced the yield by 8.19% versus the regular treatment. For the −0.5 + 0.25 mm fraction, the grade of copper was increased by 7.35% after the swelling treatment. In addition, the main trace elements of the electrical components can be enriched in the coarse fraction. An analysis of the infrared spectra of the organic solvent before and after the swelling treatment revealed that the compositions of the organic solvent and the resins remained unchanged with this treatment. The swelling process of printed circuit boards was illustrated by the non-uniform effects of thermal expansion of materials and the interaction of organic solvent with nonmetal. Further, the hydrogen bonds between the dimethylacetamide and the resin molecules were expressed by a molecular structure diagram. Overall, this method can achieve metal liberation and enrichment in the coarse fraction, reducing the generation of fine particles and organic solvent can also be recycled. Thus, this study provides an alternative approach to improve the crushing efficiency of waste printed circuit boards.

Extractants Based on Coordinating Liquid Polar Solvents for Removal of Sulfur Compounds from Diesel Fuels

To remove sulfur-containing compounds (SCC) from the diesel fraction 200–360 °C extraction systems have been created based on coordinating organic solvents—dimethylformamide and dimethylsulfoxide, metal chlorides (CoCl2, CuCl2, CdCl2, MnCl2 and CrCl3), and metal trifluoroacetates (Co(TFA)2, Cu(TFA)2 and Mn(TFA)2). Using PMR spectroscopy the coordination of metal chloride and metal trifluoroacetate on the oxygen atom in the carbonyl group of DMF was shown to redistribute electron density in the solvent molecule and to enhance properties of the acceptor center localized on the nitrogen atom. The removal of sulfur-containing compounds from the diesel fraction proceeded under mild conditions—at the temperature of 25 °C and atmospheric pressure. The degree of SCC removal from the diesel fraction in 30 minutes extraction was more than 90%. The interaction of organic solvents with metal salts and sulfur-containing compounds of the diesel fraction was considered within the framework of the concept of “hard and soft acids and bases” (HSAB). The most complete SCC extraction was carried out with DMF-Mn(TFA)2, MnCl2 and CrCl3 systems, that was probably connected with the implementation of the ‘hard base–hard acid’ system.

Interactions of Organic Solvents at Graphene/α-Al2O3 and Graphene Oxide/α-Al2O3 Interfaces Studied by Sum Frequency Generation

The adsorption of 1-hexanol from cyclohexane-d12 at single-layer graphene/α-Al2O3 interfaces was probed at mole percent values as low as 0.05 in the C–H stretching region using vibrational sum frequency generation (SFG). The SFG spectra are indiscernible from those obtained in the absence of graphene, and from those obtained in the presence of graphene oxide films prepared via oxygen plasma treatment of pristine single-layer graphene. A Langmuir adsorption model yields observed free adsorption energies of −19.9(5) to −20.9(3) kJ/mol for the three interfaces. The results indicate that the molecular structure of the hexanol alkyl chain is subject to the same orientation distribution when graphene, oxidized or not, is present or absent at the α-Al2O3/cyclohexane-d12 interface. Moreover, it appears that the adsorption of 1-hexanol in this binary mixture is driven by hexanol interactions with the underlying oxide support, and that a single layer of graphene does not influence the extent of this interaction, even when defects are introduced to it. Finally, our structural and quantitative thermodynamic data provide important benchmarks for theoretical calculations and atomistic simulations of liquid/graphene interfaces. We hypothesize that defects emerging in graphene during operation of any device application that relies on layered solvent/graphene/oxide interfaces have little impact on the interfacial structure or thermodynamics, at least for the binary mixture and over the range of defect densities probed in our studies.

Thermodynamic Characterization of Halide−π Interactions in Solution Using “Two-Wall” Aryl Extended Calix[4]pyrroles as Model System

Herein, we report our latest experimental investigations of halide-π interactions in solution. We base this research on the thermodynamic characterization of a series of 1:1 complexes formed between halides (Cl(-), Br(-), and I(-)) and several α,α-isomers of "two-wall" calix[4]pyrrole receptors bearing two six-membered aromatic rings in opposed meso positions. The installed aromatic systems feature a broad range of electron density as indicated by the calculated values for their electrostatic surface potentials at the center of the rings. We show that a correlation exists between the electronic nature of the aromatic walls and the thermodynamic stability of the X(-)⊂receptor complexes. We give evidence for the existence of both repulsive and attractive interactions between π systems and halide anions in solution (between 1 and -1 kcal/mol). We dissect the measured free energies of binding for chloride and bromide with the receptor series into their enthalpic and entropic thermodynamic quantities. In acetonitrile solution, the binding enthalpy values remain almost constant throughout the receptor series, and the differences in free energies are provoked exclusively by changes in the entropic term of the binding processes. Most likely, this unexpected behavior is owed to strong solvation effects that make up important components of the measured magnitudes for the enthalpies and entropies of binding. The use of chloroform, a much less polar solvent, limits the impact of solvation effects revealing the expected existence of a parallel trend between free energies and enthalpies of binding. This result indicates that halide-π interactions in organic solvents are mainly driven by enthalpy. However, the typical paradigm of enthalpy-entropy compensation is still not observed in this less polar solvent.

Interaction of Organic Solvents with the Epicuticular Wax Layer of Wheat Leaves

After foliar application, compounds that are not absorbed into leaves can be removed from the leaf surface by dipping or rinsing in dilutions of organic solvents in water. However, interactions between solvent mixtures and the epicuticular wax layer have received little attention, and information on potential physical and chemical intactness of the plant surface following application of solvents is limited. In this study, wheat leaves were dipped in organic solvents at different dilutions with water, and the major component of the leaf epicuticular wax layer, 1-octacosanol, was analyzed to assess damage to the wax layer. Dipping leaves in dilutions of organic solvent higher than 60% by volume resulted in only negligible or low levels of 1-octacosanol extraction, while no 1-octacosanol was detected in any mixtures containing less than 40% organic solvent. Furthermore, analysis of leaf surfaces by scanning electron microscopy showed structural intactness of the epicuticular wax layer when organic solvent mixtures were used. Therefore, our results demonstrate that the epicuticular wax layer of wheat leaves is not altered physically or chemically by organic solvent solutions up to 40% by volume. These findings validate the use of solvent washing procedures to assess unabsorbed compounds on wheat leaf surfaces.

Interaction of organic solvents with protein structures at protein-solvent interface

The effect of non-denaturing concentrations of three different organic solvents, formamide, acetone and isopropanol, on the structure of haloalkane dehalogenases DhaA, LinB, and DbjA at the protein-solvent interface was studied using molecular dynamics simulations. Analysis of B-factors revealed that the presence of a given organic solvent mainly affects the dynamical behavior of the specificity-determining cap domain, with the exception of DbjA in acetone. Orientation of organic solvent molecules on the protein surface during the simulations was clearly dependent on their interaction with hydrophobic or hydrophilic surface patches, and the simulations suggest that the behavior of studied organic solvents in the vicinity of hyrophobic patches on the surface is similar to the air/water interface. DbjA was the only dimeric enzyme among studied haloalkane dehalogenases and provided an opportunity to explore effects of organic solvents on the quaternary structure. Penetration and trapping of organic solvents in the network of interactions between both monomers depends on the physico-chemical properties of the organic solvents. Consequently, both monomers of this enzyme oscillate differently in different organic solvents. With the exception of LinB in acetone, the structures of studied enzymes were stabilized in water-miscible organic solvents.

Backscattering Interferometry: An Alternative Approach for the Study of Hydrogen Bonding Interactions in Organic Solvents

Intermolecular interactions involving hydrogen bonds are responsible for catalysis and recognition. Traditional methods used to study hydrogen-bonding interactions are generally limited to relatively large volumes and high substrate concentrations. Backscattering Interferometry (BSI) provides a microfluidic platform to study these interactions in nonaqueous media at micromolar to nanomolar concentrations in picoliter volumes by monitoring changes in the refractive index.

Spherical Self-aggregates Formed with an Alanine-functionalized Porphyrin Derivative in Organic Solvent

It is well known that porphyrins and phthalocyanines tend to align into one-dimensional aggregates and, therefore, are of much interest in relation to the creation of novel supramolecular architectures, such as nanowires, discotic liquid crystals, and helical ribbon structures, etc. The major driving forces operating in these architectures are considered to be π-π stacking, intermolecular hydrogen bonding interactions, and/or van der Waals interactions. For example, Shinkai and co-workers reported that self-assembled porphyrin derivatives having amide groups efficiently form fiber structures by π-π stacking as well as through intermolecular hydrogen bonding interactions in organic solvents. Particularly, the hydrogen bond forming groups in porphyrin derivatives play an important role in the formation of the final aggregation mode. Therefore, we designed an alanine-functionalized porphyrin derivative in order to form self-assembled superstructures through intermolecular hydrogen bonding interactions. The alanine-functionalized porphyrin is constructed by introducing four alkyl alanine residues onto the macrocyclic skeleton. We report here the preparation and the aggregate formation of 1 in organic solvent, as demonstrated by field-emission scanning electron microscopy (FE-SEM), energy-filtered transmission electron microscopy (EF-TEM), confocal laser scanning microscopy (CLSM), FT-IR, and fluorescence spectroscopy studies. Alanine-functionalized porphyrin 1 was synthesized in six steps as shown in Scheme 1. The alanine ethyl ester was added to a solution of the corresponding tetraphenyl carboxy acid 3. After de-ethylation of 5, treatment with 6 and diaminoacetylene 10 afforded the desired product 1 as a dark brown powder. Also, compound 2 without alanine moieties was prepared as reference. The aggregation behavior of 1 was investigated in organic solvents such as toluene or chloroform by using several microscopic, and spectroscopic methods. In order to obtain visual insights into the aggregation mode, we observed the superstructure of self-assembled 1 and 2 by FE-SEM and EF-TEM. Figure 1 shows FE-SEM and EF-TEM images of the self-assembled 1 formed in toluene. The FE-SEM and EF-TEM images of unstained samples in toluene show a spherical structure with uniform diameter of ≈600 nm, which have no hollow cavity. In contrast, compound 2 which lacked alanine moieties did not reveal any morphology due to high solubility in organic solvents. These results indicate that the alanine moiety plays a critical role in forming the self-assembled spherical structure. Also, the findings suggest that the self-assembled spherical structure of 1 might be induced mainly by strong intermolecular hydrogen bonding interactions between alanine and alanine moieties in organic solvents. Hydrogen bonding interactions of alanine moieties of 1 in toluene were evaluated by FT-IR measurements and compared with those of 2 without the alanine moiety. The absorption frequencies originating from the N-H deformation band and from the C=O stretching vibrations of 1 shifted to higher and lower wavenumbers (N-H: 1534 and C=O: 1623 cm−1), as compared to the comparable absorption frequencies for the reference compound 2 (N-H: 1556 and C=O: 1638 cm−1), indicating the formation of hydrogen bonds for almost all the amide residues of 1 (Figure S1). To have an insight on the role of hydrogen bonding between amide groups in the self-assembly of 1, we simplified the molecule 1 by replacing the alkyl chain after the amide group with methyl. It is clearly shown in Figure S2 that the hydrogen bonding between amide groups play an important role in growing by self-assembly. In particular, all the four chains seem to be involved in the intermolecular hydrogen bonding in the self-assembly. The thermodynamic stability of uuuu, uudd, and udud structures is virtually equivalent (within 0.12 kcal/mol) at the AM1 calculations (see calculation results and Scheme S1 in Supporting Information). In our experiment, the spherical self-assembled structure was

Controlled Self-Assembly of Triphenylene-Based Molecular Nanostructures

Molecular nanostructures of the disc-shaped molecule hexapentyloxytriphenylene have been fabricated on length scales ranging from 30 nm to 1.5 mum following self-assembly arising from pi-pi interactions in organic solvents. The size and density of the molecular nanostructures deposited onto glass and indium tin oxide-coated glass substrates were characterized by atomic force microscopy. Dynamic light scattering and spectroscopic evidence of predeposition aggregation in solution are presented, suggesting that the nanostructures are organized in solution and then deposited onto the substrate. Correlations between the relative solvent polarity and the size of molecular nanostructures as well as between the solute concentration in dilute solutions and their density on the substrate are discussed.

Comparative estimation of the efficiency of structure formation and dispersion interactions in organic solvents of varying nature and polarity

The solubilities of n-tetracosane and dotriacontane in more than 50 solvents (aliphatic and aromatic hydrocarbons, their halo derivatives, alcohols, ethers, ketones, amines, etc.) miscible with liquid aliphatic hydrocarbons were determined at 293±1 K. The increments of the methylene group in hypothetical extraction systems n-octane — solvent and the free energies of methylene group transfer from solvent to n-octane were calculated. The values were found to vary within wide limits. For the overwhelming majority of polar and low-polar solvents, the energies are negative due to self-association of solvents according to the type of spatial structure. Positive energies are due to the closer packing of some low-polar solvent molecules (carbon tetrachloride and cyclohexane) in the structure compared to octane and to the absence of molecular self-association. The closer packing of these molecules leads to higher efficiency of dispersion interactions between the solvents and paraffins compared to octane.

Effect of organic solvents on penicillin acylase-catalyzed reactions: interaction of organic solvents with enzymes

The effects of various organic solvents on penicillin acylase-catalyzed synthesis of β-lactam antibiotics (pivampicillin and ampicillin) have been investigated in water-solvent mixtures. The rates of penicillin acylase-catalyzed reactions were found to be significantly reduced by the presence of a small amount of organic solvent. In particular, the rate of enzyme catalysis was extremely low in the presence of ring-structured solvents and acids while enzyme activities were fully restored after removing the solvents. This indicates that interactions between the solvents and the enzyme are specific and reversible. To correlate the inhibitory effects of organic solvents with solvent properties the influence of solvent hydrophobicities and solvent activity on the rate of pivampicillin synthesis was examined. The reaction rate was found to decrease with increasing solvent hydrophobicities, and a better correlation was observed between the reaction rate and solvent activity. The effects of ionic strength on the synthesis of pivampicillin and ampicillin were also examined. The ionic strength dependence indicates that electrostatic interactions are involved in the binding of ionic compounds to the enzyme. On the basis of the active site structure of penicillin acylase, a possible mechanism for molecular interactions between the enzyme and organic solvents is suggested.

Solute/solvent interactions and their empirical determination by means of solvatochromic dyes

Abstract

Base binding to zinc picket fence porphyrins. Attractive intramolecular interactions in organic solvents

Base binding to zinc picket fence porphyrins. Attractive intramolecular interactions in organic solvents

Interaction of organic solvents with the green alga Chlorella pyrenoidosa.

Solvents are often a component of bioassay systems when water-insoluble toxicants are being tested. These solvents must also be considered as xenobiotics and therefore, as potential toxicants in the bioassay. However, the effects of solvents on the organisms being tested and their possible interaction with the test compound are often overlooked by researchers. The purpose of the present study was to compare the inhibitory effects of six solvents commonly used in pesticide bioassays towards growth of the common green alga Chlorella pyrenoidosa, and to examine the occurrence of solvent-pesticide interactions with this organism.

Positronium interactions in organic solvents

In the present work, the chemistry of the positronium (Ps) species has been investigated in pure benzene, pyridine and their mixtures with pyridine concentrations at 4.12, 6.18 and 8.24 M, respectively, using the Doppler-broadened line-shape analysis technique. It is seen that the intensities of the para-( p-Ps) and ortho-Ps ( o-Ps) in benzene and that of p-Ps in pyridine follow the Ore-model predictions while the intensity of o-Ps in pyridine is much lower than expected from this model. On the basis of these observations and of decrease in the o-Ps lifetime with increasing pyridine concentration in various organic solvents as reported in literature, it is concluded that pick-off is not the only quenching mechanism for Ps in organic solvents and pyridine is a quencher of Ps-species rather than an inhibitor. Calculations carried out considering a diffusion-controlled mechanism of Ps-quenching in pyridine via unstable (dissociative) complex/adduct formation and the bubble model show that the quenching rate is diffusion controlled and the pick-off rate is in accordance with the free-volume model. These conclusions were confirmed in the mixtures of benzene and pyridine.

Pigment-binder interactions in organic solvents

On etudie l'adsorption des liants polymeres a la surface de pigments en presence de solvants organiques

Interactions of organic solvents with aromatic heterocyclic polymers. I. m-phenylene polybenzimidazole

A new method of interpreting gas-chromatographic (GC) data for determining solvents for thermally stable polymers has been developed. An equation is derived for molar Gibbs energy of sorption in terms of chromatographically measured parameters. The polymer used in this study is poly(5,5′-bibenzimidazole-2,2′-diyl-1,3-phenylene), or PBI. A battery of 40 compounds, including solvents and nonsolvents for PBI, was studied. This method involves determining molar heats of sorption and molar Gibbs energies of sorption at infinitely dilute surface coverage. Mathematical correlations between the measured thermodynamic quantities and the solvent polarizabilities and dipole moments were developed. From these correlations it was possible to explain the behavior of known solvents of PBI and predict new solvents for this polymer. The results of the interpretation of GC data were supported by quantitative solubility experiments.

Macromolecular interactions in organic solvents

Macromolecular interactions in organic solvents