Solutions In Organic Solvents Research Articles

Influence of structural and solvation factors on spectral properties and lipophilicity of iodo- and bromosubstituted zinc(II), cadmium(II) and boron(III) dipyrromethenates

The paper presents a comparative analysis of the effect of structural and solvation factors on the spectral characteristics and lipophilicity of a series of iodo- and bromosubstituted zinc(II), cadmium(II), and boron(III) dipyrromethethenes. The studied chelates [ZnL2], [CdL2], and [BF2L] fluoresce in organic solvents solutions with a quantum yield from 1% to 50%, depending on their molecular structure and the solvent nature. It was noted that the high sensitivity of [ZnL2] and [CdL2] fluorescence to the presence of electron- and proton-donor solvents are due to the additional coordination of M···Solv or acid-base interactions ≥ N⋯H–Solv. It was found that [BF2L] have up to 1.5 times higher lipophilicity compared to [ZnL2] with the same functional substitution. The hydrophobicity of 4,4′-dibromosubstituted luminophores is noticeably higher than that of 5,5′-dibromosubstituted analogs. The obtained results indicate the prospects for the development of new effective fluorescent markers and sensors of medium polarity based on halogen-substituted dipyrromethenates.

Towards Investigating Surface Quality of Single-Crystal Silicon Optics Polished with Different Processes

A series of cleaning and etching experiments utilizing organic solvent or weak alkali solutions were performed on single-crystal silicon optics polished with different processes. Polishing-introduced fractured defects in the subsurface layer were systematically characterized using laser-induced scattering imaging and photothermal weak absorption imaging techniques. A white-light interferometer also measured the surface morphology and roughness of the samples to evaluate the surface quality of the optics. The results show that the organic solvent cleaning process can eliminate the surface contamination resulting from the environment and the near-surface polishing-introduced impurities but can not remove the fractured defects in the subsurface layer of the optics. By contrast, weak alkali solution can effectively expose the subsurface defects and decrease the concentration of the embedded absorbing impurities to some extent. The results also imply that the polishing process has a crucial effect on the surface quality (e.g., surface roughness and error) and optical performance (e.g., surface absorption) after the subsequent treatments such as cleaning or etching. The corresponding methodology of cleaning and characterization can serve as a predictive tool for evaluating the polishing level and laser damage resistance of the single-crystal silicon optics.

Waste Pharmaceutical Blister Packages as a Source of Secondary Aluminum

Waste pharmaceutical blister packages (WPBs) are a source of solid waste, which are composed of plastics and aluminum, therefore acting as a potential source for secondary aluminum. The structure of WPBs makes the recycling of aluminum notably more complex than typical aluminum recycling. Currently, WBPs are disposed of as municipal solid waste; thus, aluminum is lost from the circulation during incineration. In this work, three types of WPBs were studied, each with two plastic layers and a metallic layer. Delamination of WPBs to separate aluminum and plastic(s) was investigated by using a solution of organic solvents. The effects of temperature (30–50°C), acetone to isopropanol ratio (0–100 vol.%) and different types of WPBs on delamination behavior were investigated. The results suggest that aluminum separation and recovery from WPBs is 100% at optimum conditions. Moreover, an overall indicative flowsheet for recycling and post-processing of segregated aluminum from the plastic is also suggested.

Inverse electron-demand diels-alder reactions of tetrazine and norbornene at the air-water interface

The surface chemistry of the inverse electron-demand Diels-Alder (IEDDA) reaction at the air-water interface is elucidated. Tetrazine (C18-Tz) and norbornene derivatives (C16-NCA) were used as the reactants. Langmuir monolayers of C18-Tz, C16-NCA, and their binary mixtures were prepared on aqueous substrates. The surface properties were analyzed using the surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms, as well as fluorescence microscopy to monitor the progress of the reaction. First, to provide comparison data to evaluate the reaction on the surface, the two components were mixed in stock solutions of organic solvents for the IEDDA reaction. The Langmuir monolayer spread from the reaction solution was characterized as a function of the reaction time. In the subsequent experiments, the Langmuir monolayers were deposited onto the surface of the substrate solutions by spreading from separate stock solutions of C18-Tz and C16-NCA. The variation of the surface behavior of the monolayers with the molecular area, surface composition of the two components, compression speed of the monolayers, and the temperature was studied. We discuss the effects of the air phase in the reaction field on the reaction efficiency by comparing the results obtained from the two methods.

Amiloride is a suitable fluorescent substrate for the study of the drug transporter human multidrug and toxin extrusion 1 (MATE1)

Human multidrug and toxin extrusion 1 (MATE1; SLC47A1) is highly expressed in the kidneys and the liver. It plays a significant role in drug and endogenous compound disposition, and therefore, a rapid evaluation of its inhibition is important for drug development and for the understanding of renal and hepatic physiology. Amiloride is a potassium-sparing diuretic used for treating hypertension; it also demonstrates strong fluorescence in organic solvent or detergent solutions. In this study, we investigated the transport characteristics of amiloride by human MATE1. Cellular accumulation of amiloride was evaluated in control vector- or MATE1-transfected HEK293 cells. Cells were lysed with 1% sodium dodecyl sulfate, and fluorescence was measured using a microplate reader at wavelengths of 364ex and 409em. With ammonium prepulse-induced intracellular acidification, MATE1 transported amiloride at an extracellular pH of 7.4. The uptake demonstrated an overshoot phenomenon and saturated, with the Km and Vmax being 23.5 μM and 1.01 nmol/mg/min, respectively. MATE1-mediated amiloride transport also presented with a bell-shaped pH profile that reached a maximum pH value of 7.4. The inhibitor sensitivity of MATE1-facilitated amiloride transport was similar to those of known substrates, such as tetraethylammonium and metformin. Among the tested inhibitors, pyrimethamine demonstrated the most potent inhibition with an IC50 value of 0.266 μM. Furthermore, MATE1 was found to be inhibited by fampridine, which was previously considered to be a non-inhibitor of MATE1. This study demonstrates that amiloride is a suitable fluorescent substrate for the in vitro study of the transport activity of MATE1.

Recent Advances in Processing and Applications of Heterobimetallic Oxide Thin Films by Aerosol-Assisted Chemical Vapor Deposition.

The fabrication of smart, efficient, and innovative devices critically needs highly refined thin-film nanomaterials; therefore, facile, scalable, and economical methods of thin films production are highly sought-after for the sustainable growth of the hi-tech industry. The chemical vapor deposition (CVD) technique is widely implemented at the industrial level due to its versatile features. However, common issues with a precursor, such as reduced volatility and thermal stability, restrict the use of CVD to produce novel and unique materials. A modified CVD approach, named aerosol-assisted CVD (AACVD), has been the center of attention due to its remarkable tendency to fabricate uniform, homogenous, and distinct nano-architecture thin films in an uncomplicated and straightforward manner. Above all, AACVD can utilize any custom-made or commercially available precursors, which can be transformed into a transparent solution in a common organic solvent; thus, a vast array of compounds can be used for the formation of nanomaterial thin films. This review article highlights the importance of AACVD in fabricating heterobimetallic oxide thin films and their potential in making energy production (e. g., photoelectrochemical water splitting), energy storage (e. g., supercapacitors), and environmental protection (e. g., electrochemical sensors) devices. A heterobimetallic oxide system involves two metallic species either in a composite, solid solution, or metal-doped metal oxides. Moreover, the AACVD tunable parameters, such as temperature, deposition time, and precursor, which drastically affect thin films microstructure and their performance in device applications, are also discussed. Lastly, the key challenges and issues of scaling up AACVD to the industrial level and processing for emerging functional materials are also highlighted.

Conductive, Acid-Doped Polyaniline Electrospun Nanofiber Gas Sensing Substrates Made Using a Facile Dissolution Method.

A novel dissolution method that allows for the total solvation of high-concentration, high-molecular-weight polyaniline (PANi) doped with (+)-camphor-10-sulfonic acid (CSA) is reported. Preparation of 12-16 wt % 65,000 Da PANi solutions in N,N-dimethylformamide is achievable using a simple one-pot method. Doped polyaniline solutions in common organic solvents were processed into nanofibers using a convenient single-nozzle electrospinning technique. The electrospinning of PANi-CSA into nanofibrous membranes generated substrates that were subsequently employed in colorimetric gas sensing. These substrates demonstrated linearity of response upon exposure to 50-5500 ppm ammonia at ambient (50 ± 10% RH) and high (80% RH) humidity.

Benchmarking Free Energy Calculations in Liquid Aliphatic Ketone Solvents Using the 3D-RISM-KH Molecular Solvation Theory

The three-dimensional reference interaction site model of the molecular solvation theory with the Kovalenko–Hirata closure is used to calculate the free energy of solvation of organic solutes in liquid aliphatic ketones. The ketone solvent sites were modeled using a modified united-atom force field. The successful application of these solvation models in calculating ketone–water partition coefficients of a large number of solutes supports the validation and benchmarking reported here.

On the behavior of quercetin + organic solvent solutions and their role for C60 fullerene solubilization

The nature of flavonoids in polar organic solvents solutions is studied using classical molecular dynamics simulations considering quercetin as an archetypical flavonoid and acetone, dimethylformamide and dimethyl sulfoxide as representatives of solvents with different polarity. The solvation, intermolecular forces (hydrogen bonding) and interactions of the flavonoid with the solvents are analyzed. Likewise, the role of quercetin on changing the solvent properties and the possibility of acting as a solubility enhancer for fullerenes (C60) are studied by considering the properties of C60 fullerene in quercetin plus polar solvents solutions. The reported results provide information on the nature of the considered complex liquid mixtures and analyze the possibility of using flavonoids as natural, non-toxic, modifiers of traditional polar organic solvents and to improve the solubility of complex solutes such as fullerene nanoparticles.

Self-Voluntary Polymerization with Formation of Quaternary Ammonium Groups

The reaction of spontaneous polymerization in the N, N-dialkylaminoethyl methacrylate - alkyl halide system in organic solvent solutions is considered. It is shown that polymerization in the system under study begins only after the formation of quaternary ammonium salt in the reaction medium (at a concentration of about 0.2 mol/L) by the Menshutkin reaction, as a result of quaternization of the unsaturated amine with an alkyl halide. For the explanation of the aggregate of the obtained experimental data, fundamental considerations were formulated, kinetic schemes were developed, and the corresponding mechanism of polymerization processes was proposed.

Comprehensive modelling of pharmaceutical solvation energy in different solvents

Crystallization is an important processing step in production of active pharmaceutical ingredients (API). This process is used to recover/separate the synthesized APIs for further processing to final solid dosage oral formulations. Control and understanding of crystallization are of great importance for development of high-efficient processing step in pharmaceutical manufacturing. Different types of models have been developed so far for prediction of crystallization, however development of a comprehensive hybrid model is lacking. In this work, a comprehensive hybrid model is developed based on quantum chemical calculations and artificial intelligence model. The quantum chemical calculation was used to compute the solvation energy of several solutes in various organic solvents. 42 data set was collected from literature, and the solvation energy was computed using Material Studios software. The calculated solvation energy was used to build a predictive model based on artificial intelligence (AI). Artificial neural network (ANN) was employed for prediction of API solvation energy in various solvents. KFold technique was used for validation of the model in which 1/3 of the data was used for validation of the trained neural network. It was indicated that the developed ANN is capable of predicting solvation energy versus solute and solvent, with high accuracy. R2 more than 0.999 was obtained for both training and validation stages, revealing the robustness of the developed ANN in predicting solvation energy of APIs. The results can be used as predictive tool for understanding and optimization of crystallization process.

Synthesis and structural characterization of bis-cyclometalated compounds [Ir(dFppy)2(Me4phen)]PF6 and [Ir(dF(CF3)ppy)2(Me4phen)]PF6

The synthesis and structural characterization of bis-cyclometalated compounds [Ir(dFppy)2(Me4phen)]PF6 (4) and [Ir(dF(CF3)ppy)2(Me4phen)]PF6 (5) (dFppy = 2-(2́,4́-difluorophenyl)pyridinato, dF(CF3)ppy = 2-(2́,4́-difluorophenyl)-5-(trifluoromethyl)pyridinato, Me4phen = 3,4,7,8-tetramethyl-1,10-phenanthroline) were described, and their molecular structures were confirmed by single-crystal X-ray diffraction. Both compounds 4 and 5 show intense bluish-green luminescence in a diluted solution of organic solvents. The ligand change from dFppy in 4 to dF(CF3)ppy in 5 causes a significant change in the emission-decay kinetics, increasing the observed radiative rate by 4.5 times, despite the emission wavelength experiences, only a very moderate shift. The photophysical effects are rationalized by the interplay of different emitting excited states associated with different ligand-character contributions.

An Integration Strategy to Develop Dual-State Luminophores with Tunable Spectra, Large Stokes Shift, and Activatable Fluorescence for High-Contrast Imaging

An Integration Strategy to Develop Dual-State Luminophores with Tunable Spectra, Large Stokes Shift, and Activatable Fluorescence for High-Contrast Imaging

Effect of solution nonideality on cholesterol supersaturation for liquid antisolvent crystallization

The present work aims to analyze the effect of solution non-ideality on the magnitude of supersaturation of cholesterol (3) for crystallization from its solution in organic solvent (2) using water (1) as antisolvent. Real supersaturation (S) has been computed as the ratio of activities (a 3/a 3*) at the supersaturated (x 3) and saturated (x 3*) mole fractions respectively, by multiplying the ideal solution supersaturation (Sx = x 3/x 3*) with the activity coefficient ratio [γ3/γ3*]. The values of [γ3/γ3*] are estimated using the Pharma Modified UNIFAC model. The x 3* data have been measured experimentally in aqueous organic-solvent mixtures at different values of x 1 in ethanol at three temperatures (T) in the range of 290.5 to 299.5 K, and in acetone and acetonitrile at 299.5 K. These data have been correlated in terms of x 1 and T separately for computation of Sx , [γ3/γ3*], and S. The quantitative impact of solution non-ideality on the sensitivity of S to the variations of x 1, x 3, [x 3/x 3*], T and nature of solvent are investigated computationally. It is observed that [γ3/γ3*] is less than 1.0 and is relatively more significant at lower x 1 and higher Sx , though it is almost invariant with T and solvent. The value of Sx at 299.5 K is found higher than S by 15% at Sx = 2 and by 162% at Sx = 10. The results clearly establish that it is necessary to include the solution non-ideality in the estimation of solute supersaturation, as otherwise significant errors may result in computing nucleation and growth rates.

Kinetically Controlling the Length of Self-Assembled Polymer Nanofibers Formed by Intermolecular Hydrogen Bonds.

Strong directional hydrogen bonds represent a suitable supramolecular force to drive the one-dimensional (1D) aqueous self-assembly of polymeric amphiphiles resulting in cylindrical polymer brushes. However, our understanding of the kinetics in these assembly processes is still limited. We here demonstrate that the obtained morphologies for our recently reported benzene tris-urea and tris-peptide conjugates are strongly pathway-dependent. A controlled transfer from solutions in organic solvents to aqueous environments enabled a rate-dependent formation of kinetically trapped but stable nanostructures ranging from small cylindrical or spherical objects (<50 nm) to remarkably large fibers (>2 μm). A detailed analysis of the underlying assembly mechanism revealed a cooperative nature despite the steric demands of the polymers. Nucleation is induced by hydrophobic interactions crossing a critical water content, followed by an elongation process due to the strong hydrogen bonds. These findings open an interesting new pathway to control the length of 1D polymer nanostructures.

Solvent-controlled intramolecular excimer emission from organosilicon derivatives of naphthalene

New mono-, bis- and tetra-fluorophoric organosilicon naphthalene derivatives, that are able to form intramolecular excimers have been synthesized and characterized. The synthesized compounds show only monomeric fluorescence in dilute solutions of common organic solvents, but exhibit relatively strong excimer-like emission in DMSO-water and THF-water mixtures. In all cases, the intensity of excimer fluorescence increases with increasing water content and decreases with increasing temperature. Fully and partially overlapping excimer conformations have been modeled by DFT-based calculations. Properties of different intramolecular excimers in an ensemble of four naphthalene molecules linked to a cyclotetrasiloxane ring in an all-cis arrangement are considered.

The application of logarithmic charts when evaluating the equilibrium concentrations of all particles in acid-base systems

Until recently, due to the absence of other suitable approaches, equilibrium concentrations in acid-base systems have been studied exclusively by measuring the pH of a solution. However, this method can not be used for organic (non-aqueous) solvent solutions. It is known that the ionic strength of a solution, which is a fundamental component in assessing the activity coefficient and the thermodynamic dissociation constant of an electrolyte, is influenced by the ions present in the system. The concentration of these ions is variable during interactions in aqueous and more complex non-aqueous solutions, which differ significantly in their physicochemical properties (boiling temperature, structure, permittivity, autoprotolysis constant, solvating ability, dipole moment, viscosity, etc.). Meanwhile, in order to obtain more objective and valid estimates of acid-base interactions, in addition to the activity of hydrogen ions, appropriate account should be taken of the equilibrium concentrations of all particles in the solution, which affect its ionic strength. In this article, on the basis of the law of mass action and equations describing equilibrium processes, the ionic product of a solvent, electrical neutrality and material balance in a solution, the corresponding equations were derived and a method was proposed for considering the effect of the concentrations of all particles in the system (not only hydrogen ions – pH), significantly affecting the properties of acid-base equilibrium systems. The proposed method can also be used to obtain the dependence of the equilibrium concentrations of all process substances on the state of the medium (test solution), determined by various chemical and instrumental methods in logarithmic coordinates, which makes it pos-sible to directly assess the equilibrium concentra- tions of all particles present in the system.

Organic solvent resistant Kevlar nanofiber-based cation exchange membranes for electrodialysis applications

The development of organic solvent resistant ion exchange membranes (IEMs) with high ion conductivity is of significance for broader electrodialysis (ED) applications. In this work, a series of organic solvent resistant cation exchange membranes (CEMs) has been fabricated by splitting Kevlar fabrics into small and short nanofibers, followed by modifying with 4-amino-benzenesulfonic acid monosodium salt (ABS) and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) eater via amide condensation. By tuning the content of ABS, the as-prepared poly-p-phenylene terephthalamide sulfonated polymer (PAP) CEMs (PAP-CEMs) show high ion exchange capacities (up to 2.23 mmol⋅g−1), good electrochemical performance and desired capacity of cation/anion separation in ED. To evaluate the organic solvent resistance of as-prepared CEMs, PAP-CEMs were immersed in ethanol and acetone aqueous solutions for 48 h at room temperature, respectively. The investigation demonstrates that ED with the treated CEM (the optimized PAP-0.50 CEM) still exhibits high desalination efficiencies (81.2%, in 60% (Vethanol/Vwater) ethanol solution; 82.3%, in 60% (Vacetone/Vwater) acetone solution) and concentration efficiencies (57.4%, in 60% ethanol solution; 50.9%, in 60% acetone solution). As a result, it is believed that the study here highlights a design of simple route for the preparation of CEMs, which can be potentially applied in ED for organic solvent solution systems.

Co-delivery of glial cell-derived neurotrophic factor (GDNF) and tauroursodeoxycholic acid (TUDCA) from PLGA microspheres: potential combination therapy for retinal diseases.

Retinitis pigmentosa (RP) is a group of genetically diverse inherited disorders characterised by the progressive photoreceptors and pigment epithelial cell dysfunction leading to central vision impairment. Although important advances in the understanding of the pathophysiologic pathways involved in RP have been made, drug delivery for the treatment of ocular disorders affecting the posterior segment of the eye is still an unmet clinical need. In the present study, we describe the development of multi-loaded PLGA-microspheres (MSs) incorporating two neuroprotectants agents (glial cell-line-derived neurotrophic factor-GDNF and Tauroursodeoxycholic acid-TUDCA) as a potential therapeutic tool for the treatment of RP. A solid-in-oil-in-water (S/O/W) emulsion solvent extraction-evaporation technique was employed for MS preparation. A combination of PLGA and vitamin E was used to create the microcarriers. The morphology, particle size, encapsulation efficiency and in vitro release profile of the MSs were studied. Encapsulation efficiencies of GDNF and TUDCA for the initial multiloaded MSs, prepared with methylene chloride (MC) as organic solvent and polyvinyl alcohol (PVA) solution in the external phase, were 28.53±0.36% and 45.65±8.01% respectively. Different technological parameters to optimise the formulation such as the incorporation of a water-soluble co-solvent ethanol (EtOH) in the internal organic phase, as well as NaCl concentration, and viscosity using a viscosizing agent (hydroxypropyl methylcellulose-HPMC) in the external aqueous phase were considered. EtOH incorporation and external phase viscosity of the emulsion were critical attributes for improving drug loading of both compounds. In such a way, when using a methylene chloride/EtOH ratio 75:25 into the inner organic phase and the viscosity agent HPMC (1% w/v) in the external aqueous phase, GDNF and TUDCA payloads resulted 48.86±1.49% and 78.58±10.40% respectively, and a decrease in the initial release of GDNF was observed (22.03±1.41% compared with 40.86±6.66% of the initial multi-loaded formulation). These optimised microparticles exhibited sustained in vitro releases over 91 days. These results suggest that the microencapsulation procedure optimised in this work presents a promising technological strategy for the development of multi-loaded intraocular drug delivery systems (IODDS).

Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers.

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.