Interplay of Polarity and Confinement in Asymmetric Catalysis with Chiral Rh Diene Complexes in Microemulsions

Microemulsions provide a unique opportunity to tailor the polarity and liquid confinement in asymmetric catalysis via nanoscale polar and nonpolar domains separated by a surfactant film. For chiral diene Rh complexes, the influence of counterion and surfactant film on the catalytic activity and enantioselectivity remained elusive. To explore this issue chiral norbornadiene Rh(X) complexes (X=OTf, OTs, OAc, PO₂F₂) were synthesized and characterized by X‐ray crystallography and theoretical calculations. These complexes were used in Rh‐catalyzed 1,2‐additions of phenylboroxine to N‐tosylimine in microemulsions stabilized either exclusively by n‐octyl‐β‐D‐glucopyranoside (C₈G₁) or a C₈G₁‐film doped with anionic or cationic surfactants (AOT, SDS and DTAB). The Rh(OAc) complex showed the largest dependence on the composition of the microemulsion, yielding up to 59 % (90 %ee) for the surfactant film doped with 5 wt% of AOT as compared to 52 % (58 %ee) for neat C₈G₁ at constant surfactant concentration. Larger domains, determined by SAXS analysis, enabled further increase in yield and selectivity while the reaction rate almost remained constant according to kinetic studies.

X-ray scattering study on the crystalline and semi-crystalline structure of water/PEG mixtures in their eutectic phase diagram

Mixtures of water and PEG exhibit a well known eutectic phase diagram. While the thermodynamic properties like eutectic and liquidus temperatures as well as the eutectic concentration are intensely investigated almost nothing is known about the structural properties of water and PEG in the different regions of the phase diagram. Therefore, we report on a combined DSC, SAXS and WAXS study over the full range of polymer water compositions in order to elucidate the crystalline and semi-crystalline structure. Throughout the whole phase diagram no signatures of a mixed-crystalline phase of PEG and water can be found. Below the eutectic temperature, both components demix microscopically into hexagonal ice and crystalline PEG with its well known crystalline structure. In the region between eutectic and liquidus temperature, the solid component is composed of a single phase of either pure semi-crystalline PEG (PEG rich side of the phase diagram) or pure ice (water rich side). The semi-crystalline structure of PEG, in contrast, is changed by the presence of water. Its long spacing d_ac increases due to the incorporation of water molecules in the amorphous regions, while the formation of crystalline regions seems to be enhanced, resulting in an almost unaffected crystallinity.

Solubility determination and solution thermodynamics of olmesartan medoxomil in (PEG-400 + water) cosolvent mixtures

The solubility and solution thermodynamic properties of a weakly water-soluble compound olmesartan medoxomil (OLM) in binary 'polyethylene glycol (PEG-400) + water' cosolvent compositions were determined. The 'mole fraction solubility (x _e)' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at 'T = 295.15-330.15 K' and 'p = 0.1 MPa'. The Hansen solubility parameter (HSP) of OLM, pure PEG-400, pure water, and binary 'PEG-400 + water' cosolvent compositions free of OLM were also predicted. The obtained x _e values of OLM were correlated using 'van't Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff' computational models with the error values of <4.0%. The maximum and minimum x _e value of OLM was predicted in neat PEG-400 (1.15 × 10^-2 at T = 330.15 K) and neat water (1.90 × 10^-7 at T = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The x _e value of OLM was found increased significantly with increase in temperature and PEG-400 mass fraction in all 'PEG-400 + water' cosolvent compositions including neat PEG-400 and neat water. An 'apparent thermodynamic analysis' studies presented an 'endothermic and entropy-driven dissolution' of OLM in all 'PEG-400 + water' cosolvent compositions including pure PEG-400 and pure water.

Solubilization, Hansen solubility parameters and apparent thermodynamic parameters of Osimertinib in (propylene glycol + water) cosolvent mixtures

The solubilization, Hansen solubility parameters (HSPs) and apparent thermodynamic parameters of a novel anticancer medicine osimertinib (OMT) in binary propylene glycol (P) + water (W) cosolvent mixtures were evaluated. The mole fraction solubility (x e) of OMT in various (P + W) cosolvent mixtures including neat P and neat W was determined at T = 298.2–318.2 K and p = 0.1 MPa by applying a saturation shake flask method. HSPs of OMT, neat P, neat W and (P + W) cosolvent compositions free of OMT were also estimated. The x e values of OMT were regressed with Van’t Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models with an average errors of <3.0 %. The highest and lowest x e value of OMT was estimated in neat P (2.70 × 10−3 at T = 318.2 K) and neat W (1.81 × 10−5 at T = 298.2 K), respectively. Moreover, HSP of OMT was found to be closed with that of neat P. The solubility of OMT was found to be increased significantly with an increase in temperature and P mass fraction in all (P + W) cosolvent compositions including neat P and neat W. The results of activity coefficients suggested higher molecular interactions in OMT-P combination compared with OMT-W combination. The results of thermodynamic studies indicated an endothermic and entropy-driven dissolution of OMT in all (P + W) cosolvent compositions including neat P and neat W.

Solubility determination, computational modeling, Hansen solubility parameters and apparent thermodynamic analysis of brigatinib in (ethanol + water) mixtures

The solubility and various thermodynamic parameters of an antitumor drug brigatinib (BRN) in various ethanol (EtOH) + water (H2O) mixtures were determined in this study. The mole fraction solubility (x e) of BRN in various (EtOH + H2O) mixtures including pure EtOH and pure H2O was obtained at T = 298.2–323.2 K and p = 0.1 MPa by adopting a saturation shake flask method. Hansen solubility parameters (HSPs) of BRN, pure EtOH, pure H2O and (EtOH + H2O) mixtures free of BRN were also computed. The x e values of BRN were correlated using Van’t Hoff, Apelblat, Yalkowsky–Roseman, Jouyban–Acree and Jouyban–Acree–Van’t Hoff models with mean errors of <2.0%. The maximum and minimum x e value of BRN was obtained in pure EtOH (1.43 × 10−2 at T = 323.2 K) and pure H2O (3.08 × 10−6 at T = 298.2 K), respectively. The HSP of BRN was also found more closed with that of pure EtOH. The x e value of BRN was obtained as increasing significantly with the rise in temperature and increase in EtOH mass fraction in all (EtOH + H2O) mixtures including pure EtOH and pure H2O. The data of apparent thermodynamic analysis showed an endothermic and entropy-driven dissolution of BRN in all (EtOH + H2O) mixtures including pure EtOH and pure H2O.

Solubility Data and Computational Modeling of Baricitinib in Various (DMSO + Water) Mixtures

The solubility and thermodynamic analysis of baricitinib (BNB) in various dimethyl sulfoxide (DMSO) + water mixtures were performed. The “mole fraction solubilities (x_e)” of BNB in DMSO and water mixtures were determined at “T = 298.2–323.2 K” and “p = 0.1 MPa” using an isothermal saturation technique. “Hansen solubility parameters (HSPs)” of BNB, pure DMSO, pure water and “DMSO + water” mixtures free of BNB were also estimated. The x_e data of BNB was regressed well by five different thermodynamics-based co-solvency models, which included “Apelblat, Van’t Hoff, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models” with overall deviations of <5.0%. The highest and lowest x_e value of BNB was computed in pure DMSO (1.69 × 10⁻¹ at T = 323.2 K) and pure water (2.23 × 10⁻⁵ at T = 298.2 K), respectively. The HSP of BNB was found to be closer to that of pure DMSO. Based on activity coefficient data, maximum solute–solvent molecular interactions were observed in BNB-DMSO compared to BNB-water. The results of “apparent thermodynamic analysis” indicated endothermic and entropy-drive dissolution of BNB in all “DMSO + water” combinations including mono-solvents (water and DMSO). “Enthalpy-entropy compensation analysis” showed enthalpy-driven to be the main mechanism of solvation of BNB.

Synthesis and characterization of butyl acrylate-co-poly (ethylene glycol) dimethacrylate obtained by microemulsion polymerization

The synthesis and characterization of copolymers of n-Butyl Acrylate (BA) and Poly(ethylene glycol) dimethacrylate (PEGDMA) were realized by microemulsion. In this synthesis, the relation of PEGDMA 10, 20, 30, 40 and 50% wt with respect to BA was changed. The copolymers obtained were characterized by the determination of conversions (gravimetry), infrared spectroscopy: Fourier transform (FTIR), dynamic light scattering (DLS), thermogravimetry (TGA) and differential scanning calorimetry (DSC). The results confirmed the synthesis of BA-co – PEGDMA copolymers by the identification of characteristic FTIR bands and which determined the glass transition temperature of the copolymers. The conversions were found in the range of 85% to 90%. Within the stability of the produced latex, it was observed that at 10% and 30% wt. of PEGDMA the systems were stable, but when more PEGDMA was added up 40% to 50% wt., the system became unstable. The stability of produced latexes depends on the PEGDMA contents and this must be less than 30% wt.; meanwhile the PEGDMA content greater than 30% wt. leads to unstable latexes, forming clots. Copolymers showed single glass transition temperatures between −53.37°C and −16.58°C, depending on the composition of PEGDMA in the copolymers. Resulting in the different arrangements of units of PEGDMA along in the chain affected the thermal properties of the final copolymers.

Solubility and Solution Thermodynamics of Baricitinib in Six Different Pharmaceutically Used Solvents at Different Temperatures

The preset study was undertaken to determine solubility and solution thermodynamics of a novel anticancer drug baricitinib in some pharmaceutically used mono/pure solvents including “water, ethanol, polyethylene glycol-400 (PEG-400), ethyl acetate (EA), dichloromethane (DCM) and dimethyl sulfoxide (DMSO)” at “T = 298.2 K to 323.2 K” and “p = 0.1 MPa”. The solubility of baricitinib after equilibrium (saturation state) was analyzed spectrophotometrically by applying an isothermal technique. Characterization of solid phases of initial and equilibrated baricitinib was confirmed with the help of differential scanning calorimetry (DSC). Measured solubilities of baricitinib were regressed using “van’t Hoff and Apelblat models”. DSC spectra of baricitinib showed no change in physical state of baricitinib after equilibrium. Solubilities of baricitinib (as mole fraction) were estimated highest in DMSO (1.65 × 10−1) followed by PEG-400 (1.42 × 10−1), DCM (1.29 × 10−3), ethanol (7.41 × 10−4), EA (4.74 × 10−4) and water (1.76 × 10−4) at “T = 323.2 K” and same tendencies were also noted at other temperatures studied. With the help of theoretical solubilities of baricitinib, activity coefficients were estimated. The estimated data of activity coefficients indicated higher molecular interactions in baricitinib-DMSO and baricitinib-PEG-400 as compared with baricitinib-water, baricitinib-EA, baricitinib-DCM and baricitinib-ethanol. Thermodynamic treatment of solubility values of baricitinib showed “endothermic and entropy-driven dissolution” of baricitinib in all pharmaceutically used solvents evaluated.

Solubility and Thermodynamics of 6-Phenyl-4,5-dihydropyridazin-3(2H)-one in Various (PEG 400+Water) Mixtures

The aim of this study was to determine the solubility of pyridazinone derivative 6-phenyl-4,5-dihydropyridazin-3(2H)-one (PDP-6) in different “polyethylene glycol 400 (PEG 400)+water” mixtures at temperatures “T=293.2 K to 313.2 K” and pressure “p=0.1 MPa”. The solubilities of PDP-6 were determined using an isothermal method and correlated with Apelblat, van’t Hoff and Yalkowsky–Roseman models. The maximum solubilities of PDP-6 in mole fraction were obtained in neat PEG 400 (8.46×10−2 at T=313.2 K). However, the minimum one was recorded in neat water (7.50×10−7 at T=293.2 K). Apparent thermodynamic analysis showed an endothermic dissolution of PDP-6 in all (PEG 400 water) mixtures. Based on the solubility data of the current study, PDP-6 has been considered as practically insoluble in water and soluble in PEG 400.

Properties of Hydrogen-Bonded Liquids at Interfaces

Effects of interfaces on hydrogen-bonded liquids play major roles in nature and technology. Despite their importance, a fundamental understanding of these effects is still lacking. In large parts, this shortcoming is due to the high complexity of these systems, leading to an interference of various interactions and effects. Therefore, it is advisable to take gradual approaches, which start from well designed and defined model systems and systematically increase the level of intricacy towards more complex mimetics. Moreover, it is necessary to combine insights from a multitude of methods, in particular, to link novel preparation strategies and comprehensive experimental characterization with inventive computational and theoretical modeling. Such concerted approach was taken by a group of preparative, experimentally, and theoretically working scientists in the framework of Research Unit FOR 1583 funded by the Deutsche Forschungsgemeinschaft (German Research Foundation). This special issue summarizes the outcome of this collaborative research. In this introductory article, we give an overview of the covered topics and the main results of the whole consortium. The following contributions are review articles or original works of individual research projects.