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Polymer microspheres have received attention because of their excellent properties. In this work, a polymer matrix zwitterionic amino acid stationary phase was prepared. Polyglycidyl methacrylate divinylbenzene (PGMA-DVB) microspheres was used as the matrix and successful modification with L-phenylalanine by ring-opening reaction of epoxy groups on the surface of PGMA-DVB microsphere matrix. The stationary phase was characterized by scanning electron microscopy, Fourier-transform infrared spectra, and elemental analysis. The phenylalanine-modified stationary phase was used in RPLC/HILIC mixed-mode chromatography for the separation of alkylbenzenes, polycyclic aromatic hydrocarbons, phenols, nucleosides and nucleic acids and etc. as probes, respectively. The good spatial selectivity of the stationary phase was demonstrated by the separation of biphenyl isomers. The prepared stationary phase showed good stability in alkaline condition (pH = 10) and low swelling in organic solvent mobile phase. Meanwhile, the stationary phase also showed good performance in the separation of different vitamins (Rs > 5.3), and the separation and detection of PAHs in river water. [ABSTRACT FROM AUTHOR]

Vitamin A and its derivatives are effective in many medical dermatology treatments. Isotretinoin and Tretinoin, as medication and therapeutic agents, are widely applied in dermatology to treat a variety of skin cancers and disorders. In this regards, solvent as a complex environment can surround solute molecules and change their function. For this reason, the function of medication molecules as solute highly depends on their biochemical structure and the surrounding environment. The main purpose of this study is to investigate the effective interactions between the solvent molecules with Isotretinoin and Tretinoin medications. The evaluation of the spectral characteristics based on Linear Solvation Energy Relationship (LSER) models of Kamlet–Abboud–Taft and Catalán, as well as estimating the dipole moments based on the solvatochromic method were carried out. The findings revealed that specific interactions (solvent acidity and solvent basicity), exert a greater influence than non-specific interactions (polarity/polarizability). According to the dipole moments variations, the Intra-molecular Charge Transfer (ICT) process is possible. Solvent-accessible surfaces provided a better assessment of active group sites. Furthermore, density functional theory (DFT) calculations were used to gain a profound understanding of the experimental results. The insights from this research can be valuable for pharmacists and chemists working on the development of novel medications or practical applications.

Environmental partitioning influences fate, exposure and ecological risks of chemicals. Linear solvation energy relationship (LSER) models may serve as efficient tools for estimating environmental partitioning parameter values that are commonly deficient for many chemicals. Nonetheless, scarcities of empirical solute parameter values of LSER models restricted the application. This study developed and evaluated in silico methods and models to derive the values, in which excess molar refraction, molar volume and logarithm of hexadecane/air partition coefficient were computed from density functional theory; dipolarity/polarizability parameter, solute H-bond acidity and basicity parameters were predicted by quantitative structure–activity relationship models developed with theoretical molecular descriptors. New LSER models on four physicochemical properties relevant with environmental partitioning (n-octanol/water partition coefficients, n-octanol/air partition coefficients, water solubilities, sub-cooled liquid vapour pressures) were constructed using the in silico solute parameter values, which exhibited comparable performance with conventional LSER models using the empirical solute parameter values. The package models for deriving the LSER solute parameter values, with advantages that they are free of instrumental determinations, may lay the foundation for high-throughput estimating environmental partition parameter values of diverse organic chemicals. [ABSTRACT FROM AUTHOR]

Sorption to serum albumin is essential for characterizing the distribution of chemicals in organisms. It impacts the concentration of the freely dissolved chemical in vivo and in vitro, and needs to be considered when effect concentrations at the target side are derived from nominal concentrations. Sorption to serum albumin is often characterized by the serum albumin-water partition coefficient KSA/W, which is traditionally determined using dialysis experiments. However, dialysis approaches are time-consuming and require a large amount of pure protein. Thus, we investigated affinity chromatography as a fast alternative to characterize the sorption of chemicals to serum albumin. To this end, the application of two types of serum albumin columns (bovine vs. human), different temperature settings (30°C vs. 37°C), and the impact of 2-propanol as modifier in the mobile phase were evaluated. Moreover, a linear regression model was calibrated with 49 experimentally determined log KSA/W values from the literature to predict sorption to serum albumin directly from the retention factor log kHSA.In addition, we tested a prediction approach based on linear solvation energy relationships and compared the two procedures. Further, we compiled a dataset of log kHSA values for 378 chemicals, which we classified according to their ionization state and structure, and according to environmentally relevant classes like persistent, mobile, and toxic chemicals, pesticides, and plastic additives. There was no specific trend observed for particular classes of chemicals, which means that there is a demand for determining the sorption to serum albumin for these chemicals for the correction of the effect concentration in bioassays, e.g., and to assess bioaccumulation in higher tier organisms such as fish or rodents.

[Display omitted] • Precise volumetric data on 50 aqueous ionic liquids in the highly dilute region and 30 K range are reported. • Temperature dependent standard partial molar volumes for both the salts and ions are evaluated and their accuracy verified. • Concentration- and temperature-derivative properties are analyzed and their interrelation disclosed. • Important implications toward structure making/breaking ability of ions are recognized. • LSER correlation of ion standard partial molar volumes using QC descriptors established and interpreted on molecular level. The densities of highly dilute aqueous solutions (m < 0.2 mol·kg−1) of 50 common ionic liquids (ILs) or related salts were accurately measured at seven equidistant temperatures in the range of (288.15 to 318.15) K and ambient pressure. The examined set of ILs/salts composed of 31 ions was judiciously selected to cover wide ranges of ion sizes and chemical structures and allow reliable evaluation of ionic contributions. The data were duly analyzed to infer related thermodynamic properties and information on the behavior of these systems on a molecular level. Appropriate means of mathematical statistics were used to estimate data uncertainties, assign weights to data correlations, and judge the significance of the results obtained. The standard partial molar volumes V ¯ ∞ of the ILs/salts at infinite dilution were evaluated through fitting the concentration dependence of respective apparent molar volumes to Redlich-Meyer equation and their temperature dependence was correlated to quadratic polynomial. The data presented were compared whenever possible with those available in the literature; good agreement was often found, although some data from the literature were also considerably dispersed or in error. Standard partial molar volumes of ILs/salts obeying ionic additivity were split by least-squares optimization into temperature-dependent single-ion values based on the Conway-Millero extrathermodynamic assumption. The ionic additivity of B V parameter was also identified. Its magnitude for anions is typically greater than that for cations, supporting the fact that an anion dominates the volumetric behavior of aqueous ILs. As the B V ,anion and the second temperature derivative ∂ 2 V ¯ a n i o n ∞ / ∂ T 2 were found to correlate, the two solute's water structure making/breaking ability indicators appear to speak consistently. Enhanced values of standard partial molar expansion were observed for both strongly kosmotropic and chaotropic anions and a plausible explanation of this phenomenon was suggested. To correlate and analyze the effect of ionic structure on V ¯ i o n , 298 ∞ , Linear Solvation Energy Relationship (LSER) methodology with the recently proposed four quantum chemistry computed descriptors based on DFT/COSMO approach was employed providing excellent fit (SD = 2.48 cm3·mol−1, R 2 = 0.9996). [ABSTRACT FROM AUTHOR]

L-pipecolic acid (L-PA) is a key chiral intermediate in the synthesis of many important drugs. However, there is a lack of research on the efficient extraction and purification process for L-PA. Here, eleven different organic solvents were evaluated for selective extraction of L-PA by physical extraction. Among these solvents, methyl ethyl ketone (MEK) showed the highest extraction yield of L-PA, and analysis of the linear solvation energy relationship between the solvents showed that MEK was the most suitable solvent for L-PA extraction. The highest extraction yield of L-PA was 37% under optimal conditions (pH 6, 20°C, 30 min and ratio of 1). Furthermore, the repetitive extraction of L-PA from bioconversion solution was also investigated. The MEK gave high purity of L-PA (93.1% and 22.8% yield) from the bioconversion mixture. Our study is the first approach to show easy recovery of L-PA by liquid-liquid extraction and the application of MEK extraction method to L-lysine bioconversion mixture. [ABSTRACT FROM AUTHOR]

Quartz crystal resonators coated with gas-sorptive films were characterized by analyzing their structures and their organic gas-sorption behaviors, which were then studied using statistics and computational molecular simulations. The films had carbonaceous structures that were prepared by radio-frequency (rf) sputtering of aromatic biomolecules, such as cytosine and lignin. These films had been compared with the rf-sputtered films of hydrophilic biopolymer of lignin and gelatin.The composition and morphology of each film governed the organic gas-sorption characteristics of the resonator sensors used for organic gas-sensing. The cytosine film, which was nitrogen-rich and layered, had a moderate affinity for the larger molecules of normal alcohols and acetate esters. The cytosine film is repulsive to positively-charged moieties of adsorbates. In contrast, the agarose film, which was nitrogen-poor and columnar, had a high affinity for small adsorbates with short hydrocarbon chains. Molecular flexibility of the adsorbate played an important role in the gas-sorption ability of the agarose film. Molecular dynamics simulation clarified that the weakly dipolar adsorbate-aggregate were immiscible in the cytosine adsorbent-aggregate because the collision mixture was prone to be instable. In practice, the cytosine-sputtered film had a higher gas-sorption ability for weakly dipolar species that have the longer hydrocarbon chains.

The solvent effects on C=O stretching vibrational frequency, ν(C=O), of ketoprofen (KETO) were studied experimentally using attenuated total reflection infrared spectroscopy (ATR-IR). The experimental ν(C=O) of KETO were correlated with empirical solvent parameters, including the Kirkwood–Bauer–Magat (KBM) equation, the acceptor numbers (ANs) of the solvents, the Swain equation, linear solvation energy relationships (LSERs), and the quadratic equation (QE). The solvent-induced ν(C=O) shifts of KETO displayed a better correlation with the LSER equation than with the KBM equation, ANs of the solvents, and the Swain equation. The linear effect of the solvent hydrogen-bond donor acidity (Aj) on ν(C=O) of KETO was found to be highly significant, whereas the hydrogen-bond acceptor basicity (Bj) and the interaction effect of Aj and Bj were not significant. It was also observed that the quadratic effects of Aj and Bj were slightly significant. Additionally, the linear effect of LSER parameters (π*, δ, α, and β) and the interaction effect of π*β on the ν(C=O) of KETO were highly significant. [ABSTRACT FROM AUTHOR]

Surface‐bonded zwitterionic stationary phases have shown highlighted performances in separation of polar and hydrophilic compounds under hydrophilic interaction chromatography mode. So, it would be helpful to evaluate the characteristics of zwitterionic stationary phases with different arranged charged groups. The present work involved the preparation and comparison of three zwitterionic stationary phases. An imidazolium ionic liquid was designed and synthesized, and the cationic and anionic moieties respectively possessed positively charged imidazolium ring and negatively charged sulfonic groups. Then, the prepared ionic liquid, phosphorylcholine and an imidazolium‐based zwitterionic selector were bonded on the surface of silica to obtain three zwitterionic stationary phases. The selectivity properties were characterized and compared through the relative retention of selected solute pairs, and different kinds of hydrophilic solutes mixtures were used to evaluate the chromatographic performances. Moreover, the zwitterionic stationary phases were further characterized by the modified linear solvation energy relationship model to probe the multiple interactions. All the results indicated that the types and arrangement of charged groups in zwitterionic stationary phases mainly affect the retention and separation of ionic or ionizable compounds, and for interaction characteristics the contribution from n and π electrons and electrostatic interactions displayed certain differences. [ABSTRACT FROM AUTHOR]

Room-temperature ionic liquids (RTILs) have proven to be efficient polar or highly polar stationary phases for GC. Nevertheless, the thermal stability of monocationic RTILs limits their use in high-temperature GC. To improve the thermal stability, an RTIL based on a 1-methylimidazolium derivative was anchored in a three-dimensional network using the sol–gel process. Three different strategies were compared: using the derivative pure, in combination with a polymer or copolymerised with diethoxydimethylsilane. This last method allowed for the preparation of hybrid stationary phases with satisfactory efficiency (3500 plates per meter determined by the injection of n-tetradecane at 80 °C, k = 8.19) and very good thermal stability up to 340 °C using the NTf2 counter ion. The stationary phases demonstrated a good ability to separate positional isomers and polycyclic aromatic hydrocarbons. Polarity and molecular interactions with analytes were characterized by calculating the Rohrschneider–McReynolds constants and Abraham system constants. A classification of the polarity of the new stationary phases relative to 44 stationary phases, including commercial and non-commercial ones, was performed based on the RTILs using principal component analysis. Finally, the maximal operating temperature of these new stationary phases was compared with those of the most thermally stable conventional or RTIL-based stationary phases, demonstrating that the sol–gel process is an efficient way to enhance the thermal stability of GC stationary phases. [ABSTRACT FROM AUTHOR]

Computational methods increasingly provide access for Quantitative-Structure-Activity Relationship (QSAR) models to molecular descriptors that have minimal identifiable or experimentally accessible chemical/physical properties. However, molecular information inherent in chromatographic data suggests chromatography as a convenient experimental platform for legitimizing newly proposed molecular descriptors. In this study, liquid chromatographic retention data collected on a trimethylammonium (TAM) anion exchange stationary phase was used to evaluate two new molecular descriptors, P− and P+ developed to account for contributions from ion-π interactions. In the Linear Solvation Energy Relationship (LSER) model, the P− and P+ parameter replaced E. Incorporation of the new parameters was most impactful on S (sconv= −0.173 ± 0.070 vs. smod -0.115 ± 0.081). The remaining coefficients (v, b, c) were within experimental error of their respective coefficients in the conventional model. Nonparametric statistical analysis revealed comparable goodness of fits for the conventional and modified models. Finally, comparison of the contribution of individual interaction modes for substituted benzenes (log kbenzene-X) relative to benzene (log kbenzene) conducted with the new model was consistent with chemical intuition for the model-attributed ion − π and other individual interaction modes. Thus, adoption of P descriptors into the LSER model provides a convenient means for exploring models for weak ion − π interactions. [ABSTRACT FROM AUTHOR]

• Retention behaviour are considered in NA-HILIC and SFC conditions. • S-factors, log k - % methanol dependences and LSER approaches are used. • Adsorption and partition models show good applicability in describing the retention. • Strongest factors in LSER modeling are hydrogen bonding and dipolar interactions. • Acid addition provides the most orthogonality between NA-HILIC and SFC retention. This work presents an investigation of retention characteristics of imidazoline and serotonin receptor ligands in non-aqueous hydrophilic interaction liquid chromatography (NA-HILIC) and supercritical fluid chromatography (SFC). The separation has been carried out by using methanol as a mobile phase modifier with addition of two types of additives (NH 4 HCOO; NH 4 HCOO/HCOOH) and two different stationary phases (diol; mixed-mode diol). The selectivity characteristics were observed based on S-factors, log k -log k plots and radar plots. NA-HILIC vs. SFC retention of tested compounds was also described by considering the molecular properties of the analytes within the LSER analysis. The differences between SFC vs. NA-HILIC retention of imidazoline and serotonin receptor ligands grow with the acid addition to a mobile phase, noticeably on mixed-mode diol stationary phase (S ≥ 87). In addition, the good selectivity performances of the certain NA-HILIC and SFC conditions were confirmed by good separation of structurally related compounds (α ≥ 2). The molecular basis of NA-HILIC and SFC retention were explained by using Abraham's equation. The dominant analyte descriptors influencing retention were hydrogen bonding and dipolar interactions. The current study will present the theory, and discuss the applicability within the SFC vs. NA-HILIC regimes. In this way, it was provided the placing of two relatively new methods (SFC, NA-HILIC) in the map of modern analytical chromatography in terms of the pharmaceutical analysis. [ABSTRACT FROM AUTHOR]

• Study on SFC mechanism by LSER characterization of five C8 stationary phases. • Discussion about the influence of C8 bonding density on SFC selectivity. • Complementarity of five C8 stationary phases proved by the vector angle. • H-bonding interaction can be greatly affected by the modifier's type and proportion. Supercritical fluid chromatography (SFC) today represents an alternative technique in analytical chemistry due to its obvious benefits in kinetic performance and its complementarity to liquid chromatography. In this paper, a series of alkylsiloxane-bonded stationary phases were synthesized and evaluated to expand their SFC applications. Five kinds of non-endcapped C8 stationary phases (C8-1 to C8-5) with increasing bonding density were synthesized, and the carbon content was 3.91%, 6.07%, 7.97%, 8.65% and 9.10% respectively. Retention mechanism of the C8 phases in SFC in SFC was investigated by the use of a linear solvation energy relationship (LSER) model. Results underlined a close relationship between the bonding density of alkyl chain and the dispersion and polar interactions of the stationary phase. Complementary evaluation was studied based on the calculation of vector angle (θ), and the widest θ of 123° was found between silica and C8 with the highest bonding density. Selective diversity also existed between the two C8 phases with the highest and lowest bonding densities. In addition, the effect of modifier on the SFC mechanism was investigated. Modifiers (methanol, ethanol, isopropanol and acetonitrile) had insignificant influence on the dispersion interaction but they mainly affected the hydrogen bonding interaction by changing the LSER parameters a and b. Finally, C8 and silica columns were applied for separation of eight amide alkaloids of Piper kadsura. Silica provided better retention but limited selectivity while C8 can distinguish alkaloids different in alkyl chain, double bond and cis - trans structure. This research further contributed to demonstrate the potential of alkylsiloxane-bonded stationary phase in improving selectivity of SFC. [ABSTRACT FROM AUTHOR]

Abstract Graphene quantum dots (GQDs) were chosen as functional material to improve the separation performance of C 18 column since GQDs could provide multiple interactions such as hydrophilic, π-π stacking and hydrogen bonding interactions. In this study, a novel octadecyl modified GQDs-bonded silica (C 18 /GQDs/SiO 2) stationary phase was prepared and applied in reversed-phase and hydrophilic interaction liquid chromatography. This column showed satisfactory separation performance for both hydrophobic, polar and hydrophilic compounds including polycyclic aromatic hydrocarbons, alkylbenzenes, anilines, phenols, aromatic acids, alkaloids, nucleosides and nucleobases. Through investigating the impact of organic solvent content on retention, it was found this new stationary phase had typical characteristics of hydrophobic/hydrophilic chromatography. Compared with commercial C 18 column, this column showed better separation performance for polar aromatic compounds because the introduction of GQDs provided more interactions such as π-π stacking, hydrophilic and hydrogen bonding interaction with analytes. To get an in-depth understanding of the retention mechanism, linear solvation energy relationship model was established for both C 18 /GQDs/SiO 2 and C 18 columns, theoretically calculated data indicated that C 18 /GQDs/SiO 2 column had higher π-π stacking and hydrogen-bonding acceptance ability. C 18 /GQDs composite stationary phase equipped with hydrophobic/hydrophilic properties has great prospect in separation science. Graphical abstract fx1 Highlights • A novel graphene quantum dots-functionalized C 18 stationary phase. • Typical characteristics of hydrophobic/hydrophilic chromatography. • Good separation performance for several kinds of compounds. • Better polar and hydrophilic selectivity over conventional C 18 stationary phase. • Higher π-π stacking and hydrogen-bonding acceptance ability. [ABSTRACT FROM AUTHOR]

• Synthesis and evaluation of four aromatic stationary phases with LSER model in SFC. • The phases provided π-π and hydrogen bonding interactions to ensure retention capacity. • Electrostatic interactions that were regulated by additives were the key to peak shape. • 9 flavonoids and 4 alkaloids were separated using the aromatic stationary phases in SFC. In the last decade, the separation application based on aromatic stationary phases has been demonstrated in supercritical fluid chromatography (SFC). In this paper, four aromatic stationary phases involving aniline (S-aniline), 1-aminonaphthalene (S-1-ami-naph), 1-aminoanthracene (S-1-ami-anth) and 1-aminopyrene (S-1-ami-py) were synthesized based on full porous particles (FPP) silica, which were not end-capped for providing extra electrostatic interaction. Retention mechanism of these phases in SFC was investigated using a linear solvation energy relationship (LSER) model. The aromatic stationary phases with five positive parameters (a, b, s, e and d+) can provide hydrogen bonding, π-π, dipole-dipole and cation exchange interactions, which belong to the moderate polar phases. The LSER results obtained using routine test solutes demonstrated that the aforementioned interactions of four aromatic stationary phases were influenced by the type and bonding density of the ligand, but to a certain extent. Furthermore, the LSER data verified that the S-1-ami-anth column based on full porous particles silica had higher cation exchange capacity (d+ value), compared to the commercialized 1-AA column (based on the ethylene-bridged hybrid particles). The relationship between the d+ value and SFC additive was quantitatively proved so as to regulate electrostatic interaction reasonably. This value was greatly increased by phosphoric acid, slightly increased by trifluoroacetic acid and formic acid, but significantly reduced by ammonium formate and diethylamine. Taking the S-1-ami-naph column as an example, better peek shape of the flavonoids was obtained after the addition of 0.1 % phosphoric acid in MeOH while isoquinoline alkaloids were eluted successfully within 11 min after adding 0.1 % diethylamine in MeOH. Combined with the unique π-π interaction and controllable electrostatic interaction, the aromatic stationary phases in this study have been proven to have expandable application potential in SFC separation. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have turned out to be one of the best choices to fabricate mixed-mode stationary phases, this work aimed to investigate the possibility and merit of copolymerizing cations and anions as modifications. We prepared two ILs stationary phases, one of which was constructed by copolymerizing cation and anion (p -vinylbenzene sulfonate). Two stationary phases were characterized and comprehensively evaluated. The stationary phases showed great repeatability (RSD <0.87%) and high efficiency (up to 83,810 plate/m). Both stationary phases can operate under a mixed mode of reversed phase/hydrophilic interaction/ion exchange chromatography (RPLC/HILIC/IEC). Chromatographic evaluation results revealed that copolymerized anions endow stationary phase superior selectivity under RPLC and HILIC modes, so hydrophobic terphenyls isomer (under ACN/H 2 O = 35/65) and hydrophilic nucleotides and bases (under ACN/100 mM NH 4 FA buffer = 90/10) are better separated. Organic and inorganic anions showed entirely different retention behaviors on two stationary phases, and the mechanism was investigated by linear solvation energy relationship (LSER) and thermodynamic analysis. This work proved that copolymerizing cations and anions of ILs could be a promising method to prepare stationary phases, the retention property and mechanism need further research. [Display omitted] • Anion and cation were graft copolymerization as stationary phases modification. • Two stationary phases can operate under mixed mode. • Copolymerized anion enhances the separation selectivity under RPLC and HILIC. • The retention mechanism was researched by LSER and thermodynamic analysis. [ABSTRACT FROM AUTHOR]

The effect of solvent atmosphere on the electronic absorption properties of 2-aminothiazole based monoazo disperse dyes are studied. The synthesized monoazo dyes with different substituents on the para position of phenyl ring led to changes in the absorption properties of these dyes. Further, the positive solvatochromism data was evaluated to get the excited and ground state dipole moment ratio of the dyes. The Kamlet-Taft and Catalan polarity scales were employed wherein the solvent basicity and dipolarity is responsible for the bathochromic shift with increase in solvent polarity. The free amino group in the dyes made it responsive towards protonation by trifluoroacetic acid. The acidochromic behavior of the dyes was studied and D1, D3, and D4 exhibited major color change to longer wavelength with emergence of a new red shifted absorption band at 556 nm, 580 nm, and 540 nm, respectively, in their absorption spectra. Thus with help of simple UV-Vis absorption studies, we have studied the intermolecular interactions of the 2-aminothiazole based mono azo acidochromic probe. [ABSTRACT FROM AUTHOR]

Abstract During the last decade, the naturally occurring yellow Enone has drawn considerable attention due to its wide applications in biological, medical and pharmaceutical phenomena. The properties of molecular surrounding media can modify its various properties. In this work, spectral properties of three Enone derivatives were studied in various solvents by spectroscopic and theoretical techniques. As expected, the results show that photo-physical behavior of the Enone solutes depends strongly on the solvent–solute interactions and the nature of the solvent, along with different attached groups on the solute structures. In order to investigate the solvent–solute interactions and media effect on spectral variations, linear solvation energy relationships suggested by Kamlet–Abboud–Taft and Catalán parameters, were used. It was observed that the excited state dipole moments of Enone drugs are higher than those in the ground state, which increase the probability of charge transfer mechanism. The experimental results were also confirmed by density functional theory and its related time-dependent calculations including NBO analysis. The achieved results would help us to better understand the photo-physical properties and reveal essential information about the interaction of structural functional groups of Enone drugs in different media. Graphical abstract Unlabelled Image Highlights • Specific and non-specific interactions in solvents are major interactions of Enonic drug molecules. • The spectral properties of Enone drugs are evaluated by spectroscopic and theoretical techniques. • Photo-physical properties of Enone drugs depend on media induced interactions. • The variations of ground and excited state dipole moments show that ICT occurs. • The results about molecular interactions show the behavior of Enone drugs in body systems. [ABSTRACT FROM AUTHOR]

Solvent molecules as an important factor can modify the photo-physical behavior of organometallic complexes. For precise investigation, in this paper, the spectral behavior of some groups of copper complexes with different substituents were studied in various solvent media. In this case, the linear solvation energy relationships concept was used for determination of various contribution of media induced specific and non-specific interactions on the photo-physical behavior of various forms of organometallic complexes with azo-containing Schiff-base dyes. Moreover, the calculated dipole moments indicate that samples with different forms tend to have polar structure in the excited state as compared to those in the ground state. By exploiting of calculated dipole moments and obtained quantitative results in the ground and excited states, the dominant solvent induced resonance structures were also estimated. The obtained experimental results can give more information about how these samples can behave in various physical, chemical and biological phenomena. [ABSTRACT FROM AUTHOR]

Abstract Substantial variability in sorption capacity of black carbon (BC) has been a major challenge for accurate fate and risk assessment of organic pollutants in soils and sediments. 16 model organic sorbates (log K OW = 0.38–4.21) encompassing diverse chemical functionalities were used to probe the sorption capacity of two diesel soot samples representative of graphitic BC (BC1, specific surface area (SSA) = 87 m2/g) and amorphous, oxygenated BC (BC2; SSA = 3.6 m2/g). The BC-water sorption coefficients (log K BC) of the model sorbates were determined using reversed-phase liquid chromatography (RP-LC) on soot-filled columns. It was found that mass-based log K BC 's of BC1 (1.64–3.66 L/kg BC) exceeded those of BC2 (0.68–3.48 L/kg BC) consistently for all model sorbates. However, area-normalized log K BC 's of BC2 were larger than those of BC1, suggesting that the overall sorption was more favored on the oxygenated sorbent per area basis. Linear solvation energy relationships (LSERs) for sorption onto BC1 and BC2 were found to be log K BC = (2.49 ± 0.65) E + (−2.71 ± 0.88) S + (1.17 ± 0.46) A + (2.52 ± 0.34) V and log K BC = (1.12 ± 0.39) E + (−1.68 ± 0.32) S + (−3.70 ± 0.57) B + (4.37 ± 0.38) V + (−1.51 ± 0.22), respectively. The LSERs indicated that sorption onto soot was generally enhanced with increasing non-specific van der Waals and decreasing cavitation cost (i.e., eE , sS , and vV terms). The log K BC difference between BC1 and BC2, Δlog K BC , appeared to be correlated with the H-bonding capacity of the sorbates but not log K OW. Analysis of literature and experimental log K BC 's revealed that log K BC and log SSA across different types of BC (i.e., soot, char, charcoal, activated carbon) were linearly correlated for benzene and toluene (r 2 = 0.88–0.91). This work illustrates the utility of RP-LC in determining the sorption coefficients of high-capacity sorbents and suggests the possibility of a unified sorption model for the continuum of black carbon. Highlights • Soot (BC) samples with very different characteristics were examined for sorption. • log K BC 's of 16 sorbates were determined by chromatography on prepared soot columns. • Sorption on different soot samples occur via similar mechanisms. • log K BC and log SSA are linearly correlated for benzene and toluene. • Sorption capacity of different BCs may be predictable by a common correlation. [ABSTRACT FROM AUTHOR]

Solid solubility is a significant physical property for a drug development and design. In the present work, the domperidone solubility, which has less study in the near-term, was reported, which was determined by the shake-flask method in twelve green solvents e.g. methanol, ethanol, isopropanol, n -propanol, n -butanol, isobutanol, acetonitrile, N , N -dimethylformamide (DMF), water, dimethyl sulfoxide (DMSO), N , N -dimethylacetamide (DMA), ethylene glycol (EG) at the temperatures from 278.15 to 318.15 K under atmospheric pressure ( p = 101.2 kPa). The domperidone solubility in the twelve solvents increased with the increasing temperature. At a desired temperature, they obeyed the following order from high to low in these solvents: DMA > DMSO > DMF > butanol > n -propanol > (isobutanol, EG) > ethanol > isopropanol > methanol > acetonitrile > water. The experimental solubility was described mathematically with the Buchowski–Książczak λh equation, Apelblat equation Wilson model and NRTL model. The largest percentage of relative average deviation was 3.28 × 10 −2 , and the maximum value of root-mean-square deviation was 3.16 × 10 −5 . On the basis of the Wilson model, the mixing properties, e.g. mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were computed. Moreover, the solvent effect was studied by using the concept of Kamlet-Taft Linear Solvation Energy Relationship. The type and extent and direction of solvent-solvent and solute-solvent interactions were identified. [ABSTRACT FROM AUTHOR]

The fundamental relationships between the structure and chemistry of latex nanoparticles synthesized by reversible addition fragmentation chain transfer (RAFT) controlled living polymerization and their subsequent performance as pseudostationary phases (PSP) are reported in this paper. RAFT enables the rational optimization of latex nanoparticle pseudostationary phases and control of the behavior of the PSP. Nanoparticles comprised of amphiphilic diblock copolymers of 2-acrylamido-2-methylpropane sulfonic acid-derived ionic/hydrophilic blocks and butyl- ethyl- or methyl-acrylate-derived hydrophobic blocks were synthesized in two sizes. The mobility, methylene selectivity, and efficiency of each of the six pseudostationary phases are reported, as well as the relationship between monomer quantity and NP size. Linear solvation energy relationships are reported and compared to SDS micelles and previous nanoparticle pseudostationary phases. The solvation characteristics and selectivity of nanoparticle pseudostationary phases is shown to be affected primarily by the structure of the hydrophobic copolymer block. Butyl acrylate nanoparticles 17 nm in diameter are found to provide the best overall separation performance with over 500 thousand theoretical plates generated in 6 min separations. [ABSTRACT FROM AUTHOR]

In this paper, absorption and fluorescence spectra of vitamin B 12 (cyanocobalamin) and vitamin B 6 (pyridoxine) were recorded in solvents with different polarity, at room temperature. These vitamins’ photo–physical behavior depends strongly on the solvent’s nature along with different attached groups in their structures. In order to investigate the solvent-solute interactions and environmental effect on spectral variations, linear solvation energy relationships concept, suggested by Kamlet and Taft was used. Solvatochromic method was also used for measuring the ground and excited state dipole moments of these vitamins. According to our experimental results, dipole moment of these groups of vitamins in excited state is larger than ground state. Furthermore, obtained photo-physical and interactional properties of used vitamins can give important information on how this group of vitamins behaves in biological systems. [ABSTRACT FROM AUTHOR]

In this work, spectral properties of four 4 H –Pyran derivative compounds, (Pyran (I), Pyran (II), Pyran (III) and Pyran (IV)) which are used as drugs in the treatment of some diseases have been studied in various solvents with different polarities. As expected, the results indicate that photo–physical behavior of solute depends strongly on the nature of the solvent and solute, the solvent–solute interactions, and also different attached groups on their structures. Beside these aspects, delocalization of π electrons within various resonance forms of these molecules also found to be an important factor. The solvatochromic behavior of these drug materials and their solvent–solute interactions, both specific and non–specific types were analyzed by means of linear solvation energy relationships, suggested by Kamlet and Taft. Also, vertical excitations of studied molecules were studied by time dependent density functional theory. The ground and excited state dipole moments of these drug materials and their molecular resonance structures were also evaluated via solvatochromic shift method. Both of the experimental data and quantum chemical calculations confirm higher polarities of excited states of these molecules compared to their ground states. Moreover, calculations of the density functional theory propose a charge transfer from the ends of mentioned molecules toward their –CN terminals throughout the excitation process. [ABSTRACT FROM AUTHOR]

A precursor solution to the metal–organic framework (MOF), Cd(1,4,7,10-tetrakis(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane), was aged in a surface-functionalised 250 μm-diameter capillary, to generate a film containing the constituents of the bulk phase crystalline material. EDX analysis revealed a higher ratio of ligand elements (C, N and O) to Cd in the capillary coated phase compared to that achieved from bulk synthesis in a vial. Separation performance of the coated capillary for gas chromatography (GC) was compared to the performance of the original MOF crystals packed in tips for liquid elution chromatography (LEC) towards the separation of polycyclic aromatic hydrocarbons (PAHs) and small probe analytes with different properties. This study showed that different retention mechanisms were observed for the same set of analytes in gas and liquid phases. Independently of the trend of vapour pressure difference, the GC result showed less specific size selective retention, but with stronger retention towards larger PAHs. A linear solvation energy relationship correlation further revealed enhanced retention contributions (positive stationary phase descriptor values) by cavity formation/dispersion interactions and H-bonding with acid functionality of the probe analytes in both GC and LEC (though stronger in LEC), whilst H-bonding with basic functional groups slightly increased retention in GC; retention was strengthened by dipole–dipole/dipole–induced dipole interactions only in LEC. [ABSTRACT FROM AUTHOR]

The environmental partition properties of perfluoroalkyl and polyfluoroalkyl substances (PFAS) must be understood for their transport and fate analysis. In this study, isothermal gas chromatographic (GC) retention times of 60 neutral PFAS were measured using four columns with different stationary phase polarities, which indicated varying polar interactions exerted by these substances. The GC data were combined with new octanol/water partition coefficient data from this study and existing partition coefficient data from the literature and used to determine the polyparameter linear free energy relationship (PP-LFER) solute descriptors. A complete set of the solute descriptors was obtained for 47 PFAS, demonstrating the characteristic intermolecular interaction properties, such as hydrogen bonding capabilities influenced by the electron-withdrawing perfluoroalkyl group. The partition coefficients between octanol and water, air and water, and octanol and air predicted by the PP-LFER models agreed with those predicted by the quantum chemically based model COSMO therm , suggesting that both models are highly accurate for neutral PFAS and can fill the current large data gaps in partition property data. A chemical partitioning space plot was generated by using the PP-LFER-predicted partition coefficients, showing the primary importance of the air phase for the environmental distribution of nonpolar and weakly polar PFAS and the increasing significance of organic phases with increasing PFAS polarity.

Solvent effects on the reactivity of cycloalkenecarboxylic, cycloalkeneacetic, 2-substituted cyclohex-1-enecarboxylic, 2-substituted benzoic, 2-substituted cyclohex-1-eneacetic, 2-substituted phenylacetic, 2-phenylcyclohex-1-enecarboxylic, 2-phenylbenzoic and 2-phenylacrylic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet–Taft solvatochromic equation. The correlations of the kinetic data were realized by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the proposed mechanism. Solvation models for all the investigated acids are suggested. The quantitative relationship between the molecular structure and the chemical reactivity is also discussed.

Solvent effects on the reactivity of cycloalkenecarboxylic, cycloalkeneacetic, 2-substituted cyclohex-1-enecarboxylic, 2-substituted benzoic, 2-substituted cyclohex-1-eneacetic, 2-substituted phenylacetic, 2-phenylcyclohex-1-enecarboxylic, 2-phenylbenzoic and 2-phenylacrylic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were realized by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the proposed mechanism. Solvation models for all the investigated acids are suggested. The quantitative relationship between the molecular structure and the chemical reactivity is also discussed.

• Fluorosolvatochromism reflects the nature of bridge on the intramolecular charge transfer. • Structural effect has shown a great effect on intramolecular charge transfer properties. • Planar vs nonplanar optimized geometry in the ground and excited states. • Non-Specific interactions are dominating the photophysical properties. • The fluorescence lifetime decreases as the emission energy increases. Effect of the bridge structure on the photophysical properties of D-π-A of structurally similar 2,5-diphenylthiophene (cpd. I) and 2-(5-phenylfuran-2-yl)pyridine (cpd. 2) derivatives having the same electron donating and electron withdrawing groups were studied in different solvents. Solvent effect on the absorption and fluorescence emission spectra as well as their excited state decay were studied in detail. Introduction of 2,5-diphenylthiophene and 2-(5-phenylfuran-2-yl)pyridine between methoxy and carbonitrile groups lead to a shift of about 20 nm in both the absorption and fluorescence emission maxima of the former. Stokes shift of about 90 nm was observed for both compounds in protic solvents and polar aprotic solvents and decreases as the solvent polarity decreases. The solvatochromism in the fluorescence emission spectra was higher than the observed in absorption spectra, indicating higher dipole moment in the excited state than in the ground state for both compounds. DFT and TD-DFT optimized geometry calculations show that (I) is planar in the excited state while (II) is planar in both the ground and excited states reflecting the importance of the bridge structure on the geometry in the ground and excited states. Theoretical calculations of the dipole moment change from the ground to the excited states were consistent with the values obtained from Lippert-Mataga relationship and higher than values obtained from Reichardt-Ravi relationship. It has been found that the fluorescence lifetime of both compounds was found to decrease as the emission energy increases and being higher for (II) than for (I), and also was found to increase as the solvent's dielectric constant increases. All photophysical properties were found to correlate well with Reichardt's solvent polarity parameter, E T N. We have employed Kamlet-Taft, Catalán and Laurence et al. multi-parametric relationships to assign the contribution of the specific and non-specific solute–solvent interactions. Non-specific interactions were found to be mostly dominating in all cases. [ABSTRACT FROM AUTHOR]

Dependence of the Stokes shift, Δν, versus E T N. [Display omitted] Photophysical properties of two thiophene salts of the form D-π-A+ are studied in several solvents and at various pH values of the aqueous solution. The studied compounds embrace methoxy group as electron donating moiety at one end and cationic amidine group with and without fluorine atom at the ortho position of the amidine group as the electron withdrawing group at the other end of the molecules and separated by thiophene ring. The two thiophene derivatives are 4-(5-(4-methoxyphenyl)thiophen-2-yl)benzamidine hydrochloride salt (MOTB) and 2-fluoro-4-(5-(4-methoxyphenyl) thiophen-2-yl)benzamidine hydrochloride salt (FMOTB). The observed changes in the fluorescence emission spectra with the nature of the solvent were found to be much more pronounced than the corresponding absorption spectra which signify an emission from the intramolecular charge transfer state. The higher bathochromic shift in the fluorescence emission spectra than the absorption spectra indicates that the excited state dipole moment is larger than that of the ground state. It has also been observed that the presence of the fluorine atom in the electron withdrawing part does not show any changes in the absorption spectra while a clear bathochromic shift is observed in the fluorescence emission spectra indicating an enhanced strength of the electron withdrawing ability in case of FMOTB. Effect of pH was also studied and pK a values were evaluated. The observed photophysical properties were correlated to the normalized solvent polarity parameter (E T N) when solvents are classified to protic and aprotic solvents. This designates the importance of hydrogen bonding interactions. We have also applied a couple of linear solvation energy relationships for better understanding of the exact contribution of each solvent parameter on each photophysical property. We have found that both Catalán's and Laurence's treatments show that the photophysical properties are mainly controlled by the solvent's non-specific interactions. However, these models were not sufficient to interpret the observed data without the inclusion of the participation of the specific interactions. [ABSTRACT FROM AUTHOR]

The rate constants for the reaction of 2-substituted cyclohex-1-enylcarboxylic acids and the corresponding 2-substituted benzoic acids with diazodiphenyl methane were determined in various aprotic solvents at 30 ºC. In order to explain the kinetic results through solvent effects, the second order rate constants of the reaction of the examined acids were correlated using the Kamlet–Taft solvatechromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and transition state. The signs of the equation coefficients support the proposed reaction mechanism. The quantitative relationship between the molecular structure and the chemical reactivity is discussed, as well as the effect of geometry on the reactivity of the examined molecules.

The rate constants for the reaction of 2-substituted cyclohex-1-enecarboxylic acids and the corresponding 2-substituted benzoic acids with diazodiphenylmethane were determined in various aprotic solvents at 30 ºC. In order to explain the kinetic results through solvent effects, the second order rate constants of the reaction of the examined acids were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and transition state. The signs of the equation coefficients support the proposed reaction mechanism. The quantitative relationship between the molecular structure and the chemical reactivity is discussed, as well as the effect of geometry on the reactivity of the examined molecules.

A polyaniline coating was used to modify the surface of bare silica gel and octadecyl silica stationary phases to characterize the properties of altered materials. It was assumed that the mixed-mode retention was established on the basis of the polyaniline chemical structure and its combination with the original sorbents. Polyaniline was deposited onto the original surfaces during the chemical polymerization of aniline hydrochloride. The prepared materials were slurry packed into capillary columns and systematic chromatographic characterization was performed using the linear solvation energy relationship, also employing descriptors that allow inclusion of ionic interactions in the proposed retention mechanism. The retention times of 80 solutes with various chemical structures were measured in the hydrophilic interaction liquid chromatography mode. The obtained results demonstrated the significant contribution of the polyaniline coating to the retention mechanism under the given conditions; the assumed mixed-mode retention was confirmed. The dominant retention interaction for both modified stationary phases was based on the protonation of nitrogen atoms in the polyaniline structure, leading to suitable retention and selectivity for the hydrophilic analytes, especially anionic and zwitterionic species. Thus, especially, the polyaniline-coated bare silica gel sorbent seems to be promising for potential applications related to the separation of polar compounds. [ABSTRACT FROM AUTHOR]

Frequent use of triarylmethane and its derivatives in many drugs makes the investigation of specific and non-specific interactions and spatial configuration of these materials in their pharmaceutical behavior, very important. Therefore, in this paper absorption and fluorescence spectra of two triarylmethane drugs ( E 133 and E 143) were studied in different solvents. The solute's photo-physical behavior depends strongly on the solvent–solute interactions and solvent's nature, along with attached groups on triphenylmethane skeleton in solvent media. In order to understand the effect of intermolecular and intramolecular interactions on spectral behaviors of these dyes, and to conceive the nature and extend of solvent-solute interactions, the spectral variations were analyzed via the linear solvation energy relationships concept, suggested by Kamlet and Taft. In addition, by means of solvatochromic method, ground and excited states dipole moments as well as dipole moment variations, from ground to excited states, were calculated, in different media. [ABSTRACT FROM AUTHOR]

Diverse biological applications of triazole molecules, makes study of these compounds intriguing. Since, the solvent effect causes different behavior in these compounds, a quantitative study of solvent effects on photo-physical properties of two triazole compounds, with similar molecular skeleton and various substituent groups on triazole ring were studied, at room temperature. The solute's photo-physical behavior strongly depends on the solute and solvent's nature, along with the solvent-solute interactions. In order to understand the effect of intermolecular interactions on spectral behaviors of these materials, and to conceive the nature and extend of solvent-solute interactions, the spectral variations were analyzed via the linear solvation energy relationships concept, suggested by Kamlet and Taft. In addition, by means of solvatochromic method, ground and excited states dipole moments as well as dipole moment variations, from ground to excited states, were calculated, in different media. [ABSTRACT FROM AUTHOR]

The triazole and its derivatives applications' in many drugs make the investigation of specific and non-specific interactions of these compounds with their environments important. Hence, absorption and emission spectra of two triazole compounds, with same molecular skeleton and different substituted groups on triazole ring, were studied in various solvents at room temperature. The solute's photo-physical behavior strongly depends on the nature of solvent and solute, along with the solvent--solute interactions. Using solvatochromic method, the samples' dipole moments variations, from ground to excited states, were investigated in solvent media. For understanding the effect of intermolecular interactions on spectral behaviors of these materials in different solvent and extend of solvent-solute interactions, the spectral variations were analyzed by means of linear solvation energy relationships concept, proposed by Kamlet and Taft. [ABSTRACT FROM AUTHOR]

The adsorption of sixteen volatile organic compounds (VOCs) in the gas phase by activated carbon (AC) generated from waste rice husk was investigated under two different levels of relative humidity (RH) by inverse gas chromatography (IGC). R850 AC had the largest surface area and was characterized. Linear solvation energy relationship (LSER) was employed to understand the interactions between R850 AC and VOCs. The major functional groups on the surface of R850 AC were C C, Si O Si, O H, and C O(H). IGC indicated that the gas/solid adsorption coefficients (log K d ) for the 16 VOCs lied in the range 4.0–6.1 (g g −1 )/(g mL −1 ) under medium RH (around 55%), but decreased under high RH (90%). Moreover, the log K d value predicted from our LSER equations was highly correlated to the experimental log K d of the R850 AC. This study demonstrates that R850 AC is a promising material for VOC removal and the established LSER equations are useful to estimate VOC adsorption. [ABSTRACT FROM AUTHOR]

Multiwall carbon nanotubes (MWCNTs) have been used as an adsorbent for evaluating the gas/solid partitioning of selected volatile organic compounds (VOCs). In this study, 15 VOCs were probed to determine their gas/solid partitioning coefficient (Log K d ) using inverse gas chromatography at different relative humidity (RH) levels. Interactions between MWCNTs and VOCs were analyzed by regressing the observed Log K d with the linear solvation energy relationship (LSER). The results demonstrate that the MWCNT carbonyl and carboxyl groups provide high adsorption capacity for the VOCs (Log K d 3.72–5.24 g/kg/g/L) because of the π -/ n -electron pair interactions and hydrogen-bond acidity. The increasing RH gradually decreased the Log K d and shifted the interactions to dipolarity/polarizability, hydrogen-bond basicity, and cavity formation. The derived LSER equations provided adequate fits of Log K d , which is useful for VOC-removal processes and fate prediction of VOC contaminants by MWCNT adsorption in the environment. [ABSTRACT FROM AUTHOR]

The differential pressure drop of carrier gas by tuning the junction point pressure of a coupled column gas chromatographic system leads to a unique selectivity of the overall separation, which can be tested using a mixture of compounds with a wide range of polarity. This study demonstrates a pressure tuning (PT) GC system employing a microfluidic Deans switch located at the mid-point of the two capillary columns. This PT system allowed variations of inlet-outlet pressure differences of the two columns in a range of 52–17 psi for the upstream column and 31–11 psi for the downstream column. Peak shifting (differential migration) of compounds due to PT difference are related to a first order regression equation in a Plackett–Burman factorial study. Increased first (upstream) column pressure drop makes the second column characteristics more significant in the coupled column retention behavior, and conversely increased second (downstream) column pressure drop makes the first column characteristics more apparent; such variation can result in component swapping between polar and non-polar compounds. The coupled column system selectivity was evaluated in terms of linear solvation energy relationship (LSER) parameters, and their relation with different pressure drop effects has been constructed by applying multivariate principle component analysis (PCA). It has been found that the coupled column PT system descriptors provide a result that shows a clear clustering of different pressure settings, somewhat intermediate between those of the two commercial columns. This is equivalent to that obtained from a conventional single-column GC analysis where the interaction energy contributed from the stationary phases can be significantly adjusted by choice of midpoint PT. This result provides a foundation for pressure differentiation for selectivity enhancement. [ABSTRACT FROM AUTHOR]