Solutions In Organic Solvents Research Articles

Synthesis of functionalized magnetite nanoparticles using only oleic acid and iron (III) acetylacetonate

The solvothermal method is a way to obtain magnetite nanoparticles with uniformity in shape and size, good dispersibility and functionalized surface. These properties are desirable in many applications in materials science and medical area. Although methods for obtaining nanoparticles with these properties are reported, the most their use several reagents to act as solvent, surfactant and reducing agent, which makes the synthesis process more difficult and expensive. In this paper, we introduced a simple method for the preparation of magnetite nanoparticles using only iron (III) acetylacetonate as metal precursor and oleic acid for all the other functions. This is possible due the constant liberation of the acetylacetone formed in the reaction, which favors the formation of the oleate, the responsible for the conditions required to obtain magnetite nanoparticles smaller than 20 nm. By this method, nanoparticles were obtained with an average size of 17 nm in a narrow size distribution, uniformity of morphology, high crystallinity and functionalized surface. The organic capping layer allows the preparation of stable colloidal solutions in organic solvents and facilitates the posterior use of nanoparticles in films, ferrofluids and nanocomposite preparation.

A Simple Theoretical Approach of Aqueous Solutions of Salts and Organic Solvents in Paper Chromatography

The purpose of this study is to determine the properties of the solvents responsible of the chromatographic phenomenon. A simple and homogeneous system of ascending chromatography on paper is described, allowing varying only one of the factors constituting it. This method made it possible to determine constants by means of a simple equation. The validity of the method is deduced from the good agreement between its mathematical expression and the experimental values obtained.

Poly(2-oxazoline)s terminated with 2,2'-imino diacetic acid form noncovalent polymer-enzyme conjugates that are highly active in organic solvents.

A great limitation for the usability of free enzymes in organic solvents is their insolubility in these media. Some surfactants are capable of solubilizing enzymes in such media, but they are hard to remove. Covalent modification of enzymes with polymers has led to polymer-enzyme conjugates (PECs) that are soluble in organic solvents, but the process is quite elaborate. Poly(2-oxazoline)s (POx) with the end group 2,2'-imino diacetic acid were shown to form reversible, nano-sized noncovalent aggregates with enzymes. These PECs give clear solutions in organic solvents. The enzymes lysozyme, horseradish peroxidase (HRP), laccase, α-chymotrypsin (CT), catalase, and alcohol dehydrogenase could be solubilized in chloroform and toluene at concentrations of up to 2 mg protein/ml. Laccase, HRP, and CT were shown to survive the transfer into the organic medium and back to water in their active form. The distribution coefficient of the proteins between water and the organic solvent was shown to be dependent on the nature of the POx backbone. All three biocatalysts exhibit greatly enhanced activity in the respective organic solvent.

Understanding the effect of molecular solvents on the microscopic network of DBU imidazole ionic liquid

In order to uncover the microscopic structure of ionic liquids (ILs) in solutions of organic solvents, a protic ionic liquid, prepared from superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with imidazole, which is so-called [HDBU]IM, has been synthesized. And the 1H NMR chemical shifts of binary mixtures, namely [HDBU]IM/ dimethyl sulfoxide (DMSO), [HDBU]IM/dimethylformamide (DMF) and [HDBU]IM/ethanol were measured at 298.15 K within whole concentrations range, which were correlated using the local composition (LC) model to obtain the local mole fractions. In addition the excess molar volumes VE and excess Gibbs energy of activation for viscous flow ΔG⁎E were calculated from experimental data of densities ρ and viscosities η of mixtures. Moreover electrical conductivities κ of all solutions were measured and correlated using empirical Casteel-Amis equation. LC analysis deduced from 1H NMR chemical shifts shows that the ability of organic solvents to destroy the network of [HDBU] IM could follow this order: ethanol>DMF > DMSO, which is consistent with the variation of VE, κ and ΔG⁎E values.

Synthesis and characterization of bacteriochlorin loaded magnetic nanoparticles (MNP) for personalized MRI guided photosensitizers delivery to tumor

HypothesisHydrophobic bacteriochlorin based photosensitizer (PS) can be effectively immobilized on MNP covered by human serum albumin (HSA). PS loading into MNP protein shell allows solubilizing PS in water solution without altering its photodynamic activity. MNP@PS can serve as diagnostic tool for tracking PS delivery to tumor tissues by MRI. ExperimentsImmobilization on MNP-HSA-PEG was performed by adding PS solution in organic solvents with further purification. MNP@PS were characterized by DLS, HAADF STEM and AFM. Absorbance and fluorescence measurements were used to assess PS photophysical properties before and after immobilization. MNP@PS internalization into CT26 cells was investigated by confocal microscopy in vitro and MRI/IVIS were used for tracking MNP@PS delivery to tumors in vivo. FindingsMNP@PS complexes were stable in water solution and retained PS photophysical activity. The length of side chain affected MNP@PS size, loading capacity and cell internalization. In vitro testing demonstrated MNP@PS delivery to cancer cells followed by photoinduced toxicity. In vivo studies confirmed that as-synthetized complexes can be used for MRI tracking over drug accumulation in tumors.

Microfluidic Inverted Flow of Ternary Water/Hydrophilic/Hydrophobic Organic Solvent Solution in a Y-Type Microchannel and a Proposal of the Response Microfluidic Analysis through the Experiment.

Two solutions that are individually fed at the same flow rate into two separate microchannels of a microchip, combine to form a single channel (a Y-type microchannel). This flow is either parallel for immiscible solutions or initially parallel, but then becomes homogeneous through diffusion, for miscible solutions. However, a new type of microfluidic behavior in a Y-type microchannel that was neither parallel nor homogeneous flow has been observed using, for example, water/acetonitrile (3:4.5, v/v) and acetonitrile/ethyl acetate (3.5:4, v/v) mixed solutions. Each mixed solution was marked with distinctive dyes and delivered at the same flow rate into a Y-type microchannel under laminar flow conditions. In the single channel, the two phases were initially observed to flow in parallel, but then apparently swapped to flow on the opposite wall while retaining parallel flow with a slight change in the components of the two phases. We have named this type of laminar flow "microfluidic inverted flow" for ternary water/hydrophilic/hydrophobic organic solvent mixed solutions. The inverted flow of a ternary water/acetonitrile/ethyl acetate system was examined in detail under various flow conditions. We also proposed a concept of response microfluidic analysis based on such microfluidic inverted flow.

Solvent-Tuned Supramolecular Assembly of Fluorescent Catechol/Pyrene Amphiphilic Molecules.

The synthesis and structuration of a novel low-molecular-weight amphiphilic catechol compound is reported. The combination of a hydrophilic tail containing a catechol unit and a pyrene-based hydrophobic head favors solvent-tuned supramolecular assembly. Formation of hollow nanocapsules/vesicles occurs in concentrated solutions of polar protic and nonprotic organic solvents, whereas a fibril-like aggregation process is favored in water, even at low concentrations. The emission properties of the pyrene moiety allow monitoring of the self-assembly process, which could be confirmed by optical and electronic microscopy. In organic solvents and at low concentrations, this compound remains in its nonassembled monomeric form. As the concentration increases, the aggregation containing preassociated pyrene moieties becomes more evident up to a critical micellar concentration, at which vesicle-like structures are formed. In contrast, nanosized twist beltlike fibers are observed in water, even at low concentrations, whereas microplate structures appear at high concentrations. The interactions between molecules in different solvents were studied by using molecular dynamics simulations, which have confirmed different solvent-driven supramolecular interactions.

An Alternative Method for Correlation and Evaluation of Mutual Diffusion Coefficients of Solutes in Organic Solvents at Infinite Dilution

Based on the linear free energy relationships theory and empirical equations, correlations of mutual diffusion coefficients of solutes in organic solvents at infinite dilution at various temperatures are proposed. Four homologues in 743 binary systems have been regressed and correlation equations for the diffusion coefficients are obtained. The mean relative deviations of the four equations are 8.63%, 8.57%, 2.96%, and 4.85%, and all of the squared correlation coefficients (R2) are larger than 0.96, indicating that the fittings are good. The results reveal that a simple form of the equation exhibits high estimation accuracy, definite theory meaning, wide applicability and wide temperature range. This study successfully combines macroscopic physical properties of substances with their molecular microstructure, providing an alternative approach for calculating of mutual diffusion coefficient.

Polycaprolactone foams prepared by supercritical CO2 batch foaming of polymer/organic solvent solutions

In this work, the batch foaming of polymeric solutions by means of supercritical CO2 (scCO2) is described. The developed process combines the advantages of processing materials from solution in organic solvents and scCO2 batch foaming to prepare foams with uniform and controllable porosity. Polycaprolactone (PCL) was selected as semi-crystalline polymer as a case study and foams from solutions in different scCO2-miscible organic solvents, namely ethyl acetate, chloroform, dioxane and dimethyl sulfoxide, were prepared.Obtained results demonstrate that processing PCL solutions by means of scCO2 batch foaming enables preparing solid polymeric foams with solvent residue close to 1 wt. %, density values in the 0.2–0.5 g/cm3 range, hundreds of microns pore size and pore walls with spherulitic morphology. The advantage of this process is herein demonstrated by the fabrication of composite PCL foams containing 30 w% of either inorganic TiO2 nanoparticles and 5-fluorouracil chemotherapeutic by processing polymeric solutions in a single step.

Structure-fluorescence relationships in 2-aryl-5-(2′-aminophenyl)-4-hydroxy-1,3-thiazoles

Five substituted 2-aryl-4-hydroxy-5-(2′-aminophenyl)-1,3-thiazoles have been studied for their fluorescence properties under neutral and alkaline conditions in solutions of various organic solvents. From comparison with the analogous 2-aryl-4-hydroxy-5-(2′-hydroxyphenyl)-1,3-thiazoles it is clear that both in neutral as well as in the deprotonated state the presence of the 2′-amino group lowers the fluorescence quantum yields (Φ). Introduction of an electron withdrawing groups into the 2-aryl group further decreases Φ. Upon deprotonation of the 4-hydroxy group a large bathochromic shift of the absorption (ΔλA = 100–125 nm) as well as emission (ΔλF = 100–120 nm) bands occurs. An intramolecular hydrogen bond between the amino and hydroxyl groups is obvious. The first absorption band of all studied compounds corresponds to a π-π* HOMO-LUMO transition with a CT character. Thiazoles 3b-f and their deprotonated forms 3b–-f– display fluorescence properties with large Stokes shift (ca 9000 cm−1 and 6000 cm−1, respectively) and moderate quantum yields (0.11–0.41), both are connected with the presence of inter and intramolecular hydrogen bonds.

Stability of the Monoelectronic Reduction Product from 1,2,5‐Thiadiazole S,S‐Dioxides. Electrochemical, Chemical, and Photoinduced Doping

AbstractThe accumulation of radical anions from 3,4‐disubstituted 1,2,5‐thiadiazole S,S‐dioxides (1) in solution of organic solvents is achieved by electrochemical, chemical and photoinduced pathways. Electrolytic and chemical reduction of 1 produces the radical anions (1•–) in high molar yields (> ca. 80%). The survival of 1•– is measured for ca. three months. The stability of the reduced state depends on its structure and the composition (solvent, reducing agent, and supporting electrolyte) of the medium in which it is generated by the chemical and electrochemical routes. In solution of polar aprotic solvents, 1•– persists even in the presence of water or oxygen. Irradiation with 254 nm light generates 1•– but only in DMF solution; the proposed reaction mechanism involves the participation of the solvent. Radical anions are characterized by cyclic voltammetry, UV‐Vis spectrophotometry and electron spin resonance spectroscopy. The chemical stability and the properties of 1/1•– make them suitable for the development of novel materials for technological applications.

Facile one‐step high‐temperature spray pyrolysis route toward metal carbide nanopowders

AbstractFine ultrahigh‐temperature ceramic (UHTC) powders have found very important applications in many fields. In this work, a facile high‐temperature spray pyrolysis (HTSP) approach is implemented for the synthesis of HfC and TaC UHTC nanopowders starting from organic solvent (e.g., ethanol or 1‐pentanol) solutions of metal precursors (HfCl4 or TaCl5). It is proposed that, during HTSP, the precursor solution droplets would continuously undergo rapid drying, thermolysis (i.e., removal of low molecular weight species such as H2, H2O, and CO), and finally in situ carbothermal reduction (CTR) process to give rise to metal carbide nanopowders. The as‐obtained materials are shown by SEM as uniform and separated nanoparticles (~90 nm), whereas TEM reveals the carbide (e.g., HfC) nanoparticles are actually even smaller (~10‐20 nm) and embedded in amorphous carbon from excess solvent decomposition. It is found that among different processing parameters, the organic solvent used and the metal precursor concentration could largely influence the formation of metal carbide. In addition, lower HTSP temperatures (≤~1500°C for HfC) only lead to oxide‐carbon mixtures while higher temperatures (≥~1650°C) promote carbide formation. The HTSP method developed in this work is simple, low‐cost and efficient, and could potentially be optimized further for future large‐scale manufacturing of ultrafine UHTC nanopowders.

Sorption of water–ethanol mixtures by poplar wood: swelling and viscoelastic behaviour

The swelling of wood upon impregnation by aqueous solutions of organic solvents is larger than swelling by pure water. This phenomenon, described as “hyperswelling”, results from specific interactions with components of the complex wood microstructure. To understand the combined effect of mixed solvents on wood properties, the specific influence of each solvent on wood biopolymers and structure must be first characterized. In this study, the effect of the impregnation of aqueous solutions of ethanol with concentrations from 0 to 100% on the physico-mechanical properties of poplar wood was investigated. For each solution, the sorption behaviour of veneer sapwood samples and the effect of sorption on wood viscoelasticity and microstructure were measured through vapour sorption gravimetry, dynamic mechanical analysis and optical microscopy monitoring. Pure water and pure ethanol showed contrasting sorption behaviour, ethanol leading to a much lower swelling and a very limited softening compared to water, despite comparable sorbed amounts. This result suggests different affinities of water and ethanol for biopolymers within wood microstructure. With mixed solutions, larger swelling and stronger variations in viscoelastic behaviour than in pure solvents were observed, confirming the synergistic effect of water/ethanol mixtures on structure and properties of wood cells. Microscopic observations evidenced that ethanol, both alone and in aqueous solutions, generates intercellular decohesion and disbonding of the different wood cell wall layers. These observations are consistent with a mechanism of partial solubilization by ethanol of lignin-related phenolic. This could lead to a release of the constraints which limit the swelling of the polysaccharide fraction of the cell wall by water. Such phenomenon is likely to be at the origin of the hyperswelling observed in mixed water/organic solvent systems.

Aggregation‐Enhanced Emission of Fluorescent‐Gemini Surfactants with High Photostability for Cell‐Membrane Imaging

Abstract In situ studies of the aggregation behavior of traditional surfactants at the liquid interface using spectroscopic methods are often significantly affected by the large volume of fluorescent groups, such as pyrene. Fluorescent‐Gemini surfactants provide an ideal solution since the fluorescent block can be designed as a spacer or a tail. In this work, we report the synthesis of a new fluorescent‐Gemini surfactant with a rigid spacer (referred to as 8‐TBT‐8). The aggregation behavior and application in cell‐membrane imaging were investigated. The unique aggregation behavior in an organic solvent and aqueous solution was studied using spectroscopy. UV–vis and photoluminescence spectra of 8‐TBT‐8 revealed that this new fluorescent surfactant forms H aggregates in organic solution to give blue emission, whereas it forms J aggregates in aqueous solution to give green fluorescence under UV light. In addition, the fluorescence intensity of 8‐TBT‐8 increases abruptly at concentrations higher than the critical micellization concentration. Good photostability and a unique structure make the synthesized Gemini surfactant very suitable for membrane imaging.

Design and Investigation of Optical Properties of N-(Rhodamine-B)-Lactam-Ethylenediamine (RhB-EDA) Fluorescent Probe.

This study presents chemical modification of a Rhodamine B (RhB) sensor probe by ethylenediamine (EDA), and investigation of its spectral as well as sensor properties to the various metals. The synthesised N-(Rhodamine-B)-lactam-ethylenediamine (RhB-EDA) fluorescent probe shows interesting optical sensor properties, and high sensitivity and selectivity to Ag+ ions among all the tested metal ions (K+, Mg2+, Cu2+, Ni2+, Fe2+, Pb2+, Na+, Mn2+, Li+, Al3+, Co2+, Hg2+, Sr2+, Ca2+, Ag+, Cd2+ and Zn2+), while the well-known Rhodamine B (RhB) fluorescent probe shows much less sensitivity to Ag+ ions, but high sensitivity to Fe2+ ions. The novel fluorescent sensor probe RhB-EDA has the capabilities to sense Ag+ ions up to µM ranges by using the fluorescence quenching approach. The probe displayed a dynamic response to Ag+ in the range of 0.43 × 10−3–10−6 M with a detection limit of 0.1 μM. The sensing system of an RhB-EDA novel fluorescent probe was optimised according to the spectral properties, effect of pH and buffer, photostability, incubation time, sensitivity, and selectivity. Since all the spectral and sensing properties were tested in green aqueous media, although many other similar sensor systems rely on organic solvent solutions, the RhB-EDA sensing probe may be a good candidate for measuring Ag+ ions in real-life applications.

Copper Plated through-Holes for 3D Electro-Thermal Systems

Three-dimensional (3D) packaging/integration of thermal devices, multi-chips, passives, sensors, electro-optics etc. is a key technical approach to optimize power density and create 3D electro-thermal systems that are optimally designed to route both thermal and electrical power. 3D electro-thermal systems are operated at high power density and temperature. These systems have to overcome the issues of high thermal-mechanical stress and poor reliability. Interconnects with plated-through holes (PTH) fabricated by using NANO3D’s eLOCOSTM process materials for thermal and mechanical management will enable the 3D electro-thermal system to withstand high thermal stress and high temperature. Low-cost electrochemical metallization was used because it drastically reduces the cost of 3D power systems by replacing costly, high-overhead metallization processes. Electroless Ni and Cu PTH. 10 mil and 20 mil PTH were fabricated in Low Temperature and High Temperature Co-fired Ceramic substrates (LTCC and HTCC, respectively). The ceramic surfaces were pre-cleaned and etched in organic solvent and alkaline solutions before an activation step. Surface activations for electroless plating were performed by using one of two methods: tin-based sensitization or silanization followed by palladium activation. A conformal barrier layer was applied to ceramic substrates via electroless plating. Nickel barrier and copper seed layers were electrolessly plated on activated LTCC substrates. Both nickel and copper readily plate inside the vias as well as on exposed surfaces. Cu PTH. Copper electroplating was performed in a suppression-based plating solution on LTCC/HTCC blanket and patterned via substrates after Ni/Cu barrier/seed layer deposition. Pulse-reverse plating in the plating solution containing two suppressors/surfactants was used to completely fill the holes and obtained a smooth copper surface (Fig. 1). The reverse-current step removes copper from the surface. Reverse-current step combined with the agitation of the plating solution are important for hole fill because it removes peaks, bulges and ridges preferentially. This eliminates buildup along the hole (via) edges that might cause the tops and bottoms to fill before the center, leaving large crevices within the via. Blanket plated substrates were analyzed in various ways post electroplating, including optical microscopy, profilometer, and adhesion testing. For Instron testing, many samples broke at the epoxy site rather than the plated copper layer. Adhesion between the copper and substrate was over 2.6 MPa. Testing Results. Thermal shock testing of NANO3D’s PTH substrates showed promising results for the adhesion of the Cu to the ceramic substrates. Only one of the samples showed obvious delamination after 500 cycles of thermal shock (Fig. 2). Of the five samples of commercial DBC used, only two alumina samples survived the 500 cycles. Both the aluminum nitride DBC showed signs of cracking in the ceramic after 200 cycles (Fig. 2). One alumina sample started showing signs of delamination around 200 cycles as well. SAM images showed the delamination in the failed samples and showed minimal delamination in a few others that was not visible under the microscope. Figure 1

Equilibrium Compositions of HF Solutions in N,N-Dimethylformamide

For HF solutions in DMF, concentration-dependent fractions of DMF molecules (α(DMF)) that remain unassociated and that enter heteroassociates (HAs) of 1 : 1, 4 : 1, and 12 : 1 molecular stoichiometries were obtained by two independent methods, namely, from an analysis of IR spectra and by calculating the material balance. The experimental way was shown to be enough exact in determining the ratio between the solvent molecules in four different states up to ~83 mol % HF. The equilibrium compositions of HF–DMF solutions were estimated over the entire range of concentrations. Starting with [HF] of ~25 mol %, more than one-half HF molecules are associated, and at [HF] of ~50–92 mol %, at least 90% of the HF molecules are associated. The equilibrium composition of HF–organic solvent (Solv) solutions in which HAs of 1 : 1, 1 : 4, and 1 : 12 molecular stoichiometries are formed, can be described by a single set of α(HF–Solv) versus concentration plots.

Thermodynamic Properties of Butyl Methacrylate Solutions in Organic Solvents

Thermodynamic Properties of Butyl Methacrylate Solutions in Organic Solvents

Enhancement of Fluorescence and Raman Scattering in Cyanine-Dye Molecules on the Surface of Silicon-Coated Silver Nanoparticles

A method of formation of a composite structure based on silver nanoparticles and a thin protective silicon film (AgNPs/Si) is developed. Enhancement of the fluorescence and Raman scattering in cyaninedye molecules deposited onto the formed nanostructure is observed. The optical properties and morphology stability of particles that are in contact with cyanine-dye solutions in organic solvents are studied. It is shown that the AgNPs/Si composite structure can be multiply used as an SERS-active surface.

Solvophobic Acceleration of a Diels–Alder Reaction in True Solutions in Organic Solvents

ABSTRACTThe rate of Diels–Alder reaction of diene 9,10‐bis(hydroxymethyl)anthracene with dienophile N‐ethylmaleimide was studied in a series of solvents with different polarity and hydrogen‐bonding ability. Enthalpies and entropies of activation were determined from the temperature dependences of the rate constants. Rate acceleration in nonaqueous protic solvents such as glycerol, propylene, and ethylene glycols was observed. In addition, enthalpy versus entropy of activation plots show a compensation pattern different from the other considered solvents, which can be linked with the solvophobic effects observed in polyhydric alcohols. However, the solvophobic acceleration was not as strong as the hydrophobic acceleration in water. Hydrogen bonding of the reactants and transition state with solvent also influences the reaction rate. The studied reaction is slightly promoted in hydrocarbon solvents in comparison with aprotic polar solvents. This was explained by hydrogen bonding of the hydroxyl groups of diene with dienophile in transition state, which requires prior breaking of the hydrogen bonds of these groups with polar solvent molecules.