Aqueous Alcoholic Medium Research Articles

Perfluorinated Anion Exchange Membranes for Alkaline Water Electrolysis

Anion exchange membranes (AEMs) have been getting great attraction in the field of alkaline water electrolysis because of their excellent barrier properties to hydrogen and oxygen. Here, we synthesized a perfluorinated AEM ionomer via one-step polycondensation reaction of a perfluorinated sulfonyl fluoride (PF-SO2F) precursor with the chemical architecture identical to Nafion® using N-phenylhydroxylamine (HPA). The synthesized NR-HPA ionomer was homogenously dispersed in an aqueous alcohol media via a supercritical fluid technique for AEM fabrication. The resulting AEM membrane has high OH- conductivity (e.g., 81 mS cm-1 at 90oC) and excellent chemical durability (e.g., ~200 hours at 80oC) even at the elevated temperatures. The electrochemical single cell performance was comparable to that of the state-of-the art alkaline membrane Zirfon® in the same measurement condition of 2 M KOH at 80oC.

Formation of metal nanostructures under X-ray radiation in films of interpolyelectrolyte complexes with different silver ion content

The specific features of the formation of metal nanoparticles under X-ray radiation in interpolyelectrolyte complex (IPEC) films based on polyacrylic acid and polyethyleneimine with different silver ion content were studied. IPEC films were irradiated in aqueous-alcoholic medium. Electron microscopy demonstrated that the formation of silver nanoparticles occurred in zones regularly located by film thickness. It was found that nanoparticle size and spatial distribution in IPEC films depended on the initial concentration of silver ions within the sample and on the absorbed dose of radiation. The obtained film nanocomposites are promising objects for application as antibacterial and catalytic materials.

Synthesis of Block Copolymers of Acrylic Acid and N-Butyl Acrylate under Reversible Chain-Transfer Conditions in a Water-Alcohol Medium

The laws of dispersion polymerization of n-butyl acrylate in an aqueous-alcoholic medium in the presence of a hydrophilic reversible addition-fragmentation chain-transfer poly(acrylic acid)-based polymeric agent with a trithiocarbonate group within the chain are investigated. It is shown that the portioned introduction of the monomer into the synthesis makes it possible to achieve higher maximum conversions. The resulting block copolymers are characterized by a relatively narrow molecular weight distribution and their number-average molecular weight increases linearly with increasing monomer concentration. The obtained dispersions of triblock copolymer poly(acrylic acid)–block-poly(n-butyl acrylate)–block-poly(acrylic acid) have a unimodal particle size distribution that persists after dialysis against water. It is shown that the synthesized dispersions may be used as a polymer matrix for immobilizing zinc oxide nanoparticles and as a polymer precursor in the process of the seeded polymerization of styrene.

Formation of chitosan—surfactant complexes in aqueous-alcohol media

The complexation of chitosan and anionic surfactant, sodium dodecyl sulfate (DDS), in aqueous-alcohol media with a variable content of an organic cosolvent (methanol, ethanol, and propan-1-ol) was studied. A complicated effect of the composition of mixed solvents on the binding parameters of DDS by chitosan was observed. The introduction of 10–20 vol.% ethanol and propan-1-ol is accompanied by an increase in the degree of cooperative binding of DDS compared to that found in an aqueous solution, which leads to a decrease in the critical concentration of association and an increase in the cooperativity parameters.

Tunable catalytic activity of gold nanoparticle decorated SBA-15/PDMAEMA hybrid system

A temperature responsive smart catalytic system based on SBA-15/poly(N,N-dimethylaminoethylmethacrylate) decorated with gold nanoparticles (NPs) was prepared. The surface graft polymerization of 2-dimethylaminoethyl methacrylate on well-structured mesoporous silica NPs was done by atom transfer radical polymerization technique in aqueous alcohol media. In situ generation of gold NPs was achieved in controlled condition. The catalytic activity was evaluated by monitoring the reduction reaction of 4-nitrophenol at various temperatures. The catalytic activity of the NPs showed a deviance from the expected Arrhenius trend at different temperatures. Above the cloud point of the grafted polymer at a given pH condition, the rate constant of the catalytic reaction dropped sharply due to shrinkage of the polymer and transition to hydrophobic state.

Isothiazoles in the Design and Synthesis of Biologically Active Substances and Ligands for Metal Complexes

The chemistry of isothiazoles is being intensively developed, which is evidenced by the wide range of selective transformations involving the isothiazole heterocycle and the high biological activity of its derivatives that can be used as effective new drugs and plant protection chemicals. Some representatives of isothiazoles have proven to be synergists of bioactive substances, which opens the way to lower the doses of drugs used and is especially important in cancer chemotherapy. In the framework of the present review, the accomplishments in the chemistry of isothiazoles over the past 18 years are examined, whilst current strategies for the synthesis of isothiazole-containing molecules and key directions of studies in this field of heterocyclic chemistry are discussed. Considerable attention is paid to chlorinated isothiazoles and strategies for their use in the synthesis of biologically active substances. In addition, a comprehensive review of existing literature in the field of metal complexes of isothiazoles is given, including the results and prospects for the practical use of isothiazole–metal complexes as catalysts for cross-coupling reactions in aqueous and aqueous–alcoholic media (‘green chemistry’).1 Introduction2 Synthesis by Ring-Forming Reactions2.1 Intramolecular Cyclization2.2 (4+1)-Heterocyclization2.3 (3+2)-Heterocyclization2.4 Syntheses by Ring Transformations3 Isothiazoles by Ring Functionalization Reactions: Nucleophilic Substitution, Cross-Coupling and Side-Chain Functionalization4 Selected Syntheses of Biologically Active Isothiazole Derivatives5 Isothiazoles in the Synthesis of Transition-Metal Complexes and in Metal-Complex Catalysis6 Conclusion

A ONE POT THREE-COMPONENT SYNTHESIS OF SPIROOXOINDOLES USING Cu-NANOPARTICLES GRAFTED ON CARBON MICROSPHERES AS CATALYST

The copper nanoparticles grafted on carbon microsphere is employed for an efficient one-pot three-component synthesis of spirooxoindole derivatives involving isatin, malononitrile and enolizable ketones such as 3-methyl-1-phenyl-2-pyrazolin-5-one, 3-methyl-1-(2-chlorophenyl)-2-pyrazoline 5-one, 4-hydroxy-6-methyl-2-pyrone and 1-methyl-4-hydroxyquinoline-2-one. The cheap starting material, easy separation, high catalytic efficiency and reusability of the catalyst for several times without loss of its efficiency, good yield of products and simple workup are promising features of the reaction in 1:1 (v/v) aqueous-alcoholic medium.

Synthesis, molecular modeling and BACE-1 inhibitory study of tetrahydrobenzo[b] pyran derivatives

β-Secretase (BACE1) has been broadly documented as one of the possible therapeutic targets for the treatment of Alzheimer’s disease. In this paper, we report the synthesis and the for β-secretase (BACE-1) inhibitory activity of new series of tetrahydrobenzo [b] pyran derivatives. One-pot synthesis of tetrahydrobenzo [b] pyrans was carried out by condensing aromatic aldehyde, malononitrile and 1,3-cyclohexanedione using ionic liquid 1-butyl-3-methyl imidazolium chloride ([bmIm]Cl−) in aqueous alcohol media. The addition of alcohol and water in the ratio of 1:2 keeps all the reactants in solution which facilitates the reaction and makes the product formation very easy. The synthesized compounds were subjected to BACE1 inhibition assay and six compounds, 4d, 4e, 4f, 4h, 4i, and 4p have shown significant IC50 values at micromolar level. Among these six active compounds, 4e was a potential inhibitor with its IC50 value in nanomolar range. All the synthesized compounds were docked onto the active site of β-Secretase enzyme.

Hydroxy- and alkoxymethylation of polyfluoroalkyl pyrazoles

A synthetic route to 1-hydroxy- and 1-alkoxymethyl-3-polyfluoroalkylpyrazoles via regioselective N-hydroxy- and alkoxymethylation of N-unsubstituted pyrazoles with paraformaldehyde has been proposed. The alkoxyalkylation of polyfluoroalkylpyrazoles proceeds in aqueous-alcohol medium, whereas hydroxymethylation requires anhydrous conditions.

3,5-[5-Arylisoxazol-3-yl(4,5-dichloroisothiazol-3-yl)]-substituted 1,2,4- and 1,3,4-oxadiazoles: synthesis, palladium complexes, and catalysis of Suzuki reactions in aqueous media

A reaction sequence involving transformations of 5-(4-methylphenyl)isoxazole and 4,5-dichloroisothiazole derivatives containing an amidoxime group at position 3 allowed to synthesize the respective 3,5-isoxazolyl(isothiazolyl)-substituted 1,2,4-oxadiazoles. Selective recyclization of 4,5-dichloro-3-(1Н-tetrazol-5-yl)isothiazole and 5-(4-methylphenyl)-3-(1Н-tetrazol-5-yl)isoxazole gave 2,5-isoxazolyl-(isothiazolyl)-substituted 1,3,4-oxadiazoles. The obtained compounds combining three azole heterocycles in one molecule formed palladium complexes that showed high catalytic activity in Suzuki reactions in aqueous and aqueous alcohol media. The bimetallic reusable Pd/Fe catalyst obtained from palladium polyazole complex retained high catalytic activity after five uses.

Volumetric Properties of Sodium Lauroylsarcosinate in Aqueous Alcohol Solutions of Methanol, Ethanol, and 1-Propanol

The work attempts to gain an insight into the solution behavior of a biocompatible surfactant, sodium lauroylsarcosinate (SLS), in aqueous alcohol media at practically used concentrations of SLS (>CMC) where the solute–solute and solute–solvent interactions of surfactant aggregates are expected to be different from that between the solvent and the constituent monomers. The study of volumetric properties stresses the importance of hydrophilic and hydrophobic interactions operative between the SLS molecules and between SLS and the solvent. Moreover, it is interesting to observe how the dominance of electrostatic interactions fades and that of hydrophobic interactions rises as the concentration of SLS is progressively increased. Also, the study of standard apparent molar volumes, and the standard volumes of transfer offers a convenient way for accounting the differences between the alcohols which stems from their differing hydrophobicity.

Reactions of 2,2′-Pyridyl with the cadmium(II) compounds: Synthesis, crystal structure, and luminescence properties of [Cd(Pic)2(H2O)2] · H2O

The reactions of 2,2'-pyridyl, (2-Py)C(O)C(O)(2-Py), with the Cd(II) compounds under various conditions are studied. The medium and nature of the anions exert a decisive effect on the compositions and structures of the formed cadmium complexes. The reaction of cadmium diacetate with 2,2'-pyridyl in an aqueous-alcohol medium in air affords coordination compound [Cd(Рic)2(H2O)2] · H2O (I) (Pic− is picolinate ion, CO2C5H4N), and its crystal structure is determined. The crystals are monoclinic: space group P21/c, a = 7.499(1), b = 15.676(1), с = 12.719(1) A, β = 94.79(1)°, V = 1490.0(2) A3, Z = 4, ρcalcd = 1.502 g/cm3. The molecular packing of compound I is a supramolecular 3D framework consisting of discrete complexes [Cd(Pic)2(H2O)2] linked by hydrogen bonds O–H…O. The coordination sphere of Cd2+ contains two O atoms and two N atoms of the ligand and two water molecules. The coordination polyhedron of Cd2+ is a distorted octahedron.

A highly selective and sensitive “Turn-On” fluorescence chemosensor for the Cu 2+ ion in aqueous ethanolic medium and its application in live cell imaging

Abstract A new rhodamine 6G derived chemosensor L has been synthesized that selectively detects the presence of Cu 2+ ion over a host of other biologically important and environmentally relevant metal ions in aqueous alcoholic medium under physiological pH (ethanol: water, 1:1, v/v, pH 7.2). The significant enhancement of fluorescence intensity of L is caused by Cu 2+ ion induced cleavage of spirolactum bond in the rhodamine moiety. This mechanism is well supported by the crystal structure of the L-Cu 2+ complex that depicts two ligand units are bonded to two Cu 2+ ions. Color of the solution changes from light orange to dark pink upon metal binding which allows naked eye detection ion as well. Confocal microscopic experiments validate that the dye is potentially useful for the selective detection of Cu 2+ ion in living cells. Therefore the dye is an excellent fluorogenic and chromogenic chemosensor for the Cu 2+ ion in aqueous ethanolic medium and the living cell as well.

Anti-bacterial and in vitro Anti-diabetic Potential of Novel Isoxazole Derivatives

Aim: To synthesize novel Isoxazole derivatives, characterize them and subject for screening anti-bacterial action and in vitro anti-diabetic activity. Methodology: Chalcones were prepared by the reaction of aromatic aldehydes with aromatic ketones in aqueous alcoholic alkaline medium. Then these were made to react with hydroxylamine hydrochloride and sodium acetate to prepare title compounds. The prepared isoxazole compounds were subjected to in vitro anti-diabetic screening by yeast and enzymatic method. All compounds were screened for antibacterial action by disc diffusion method. Results: The structure of the synthesized compounds were confirmed by IR, NMR spectral datas and screened for anti-bacterial, and anti-diabetic activities. Most effective antibacterial one possessed chlorine in the Phenyl ring attached at 5-C of isoxazole and have NH2 substitution in phenyl ring attached at 3-C of isoxazole. Compounds with significant in vitro anti-diabetic action by studying the glucose uptake by yeast cell method are with Br/NO2 substituted forR2/R3 in phenyl ring when R’2 is OH/NH2. Conclusion: Presence of halogenated aromatic ring at 5-C and amine substituted phenyl ring at 3-Cof Isoxazole exhibited moderate anti-bacterial activity. In the anti-diabetic study halogenated or nitrated phenyl ring at 5-C and hydroxyl/amine substituted phenyl ring at 3-C of isoxazole exhibited anti-diabetic action.

Facile access to zinc and cadmium selones: highly active catalysts for Barbier reactions in aqueous media.

The syntheses and structures of five mononuclear zinc and cadmium selone complexes along with a polynuclear cadmium selone 1D chain were described. The mononuclear homoleptic zinc selone complexes were the first examples of structurally characterized zinc(ii) selone complexes. The spectral properties of the zinc and cadmium selone derivatives were investigated. Interesting structural diversity, coordination geometry, and variable chemical and thermal stability were observed for these zinc and cadmium selone compounds. Besides this, the first metal selone mediated Barbier coupling was reported. These catalysts were highly active for Barbier coupling reactions in aqueous alcohol media. In addition, the scope of the catalytic reactions was further explored with eleven different aldehydes.

Electrochemical reduction of N-(2-nitro-4-R-phenyl)pyridinium salts using redox-mediators

Electrochemical reduction of N-(2-nitroaryl)pyridinium chlorides was accomplished in acidic aqueous alcoholic medium in the galvanostatic mode using tin, titanium, vanadium, and iron chlorides as redox-mediators. The use of SnCl2 as a mediator catalyst made it possible to shorten the electrosynthesis time as compared to the direct electroreduction on an electrode and prepare the intramolecular cyclization products, viz., substituted pyrido[1,2-a]benzimidazoles, in high yield. The influence of the mediator nature and its amount, current density, temperature, cathode material, medium acidity, and the substrate structure on the efficiency of reductive heterocyclization of N-(2-nitroaryl)pyridinium salts was studied.

State of fungal lipases of Rhizopus microsporus, Penicillium sp. and Oospora lactis in border layers water—solid phase and factors affecting catalytic properties of Enzymes

We demonstrated that a change in the catalytic activity of fungal lipases synthesized by Rhizopus microsporus, Penicillium sp. and Oospora lactis and their ability to absorb on different sorbents depended on the nature of groups on the solid phase surface in the model systems water: lipid and water: solid phase. Thus, the stability of Penicillium sp. lipases increased 85% in the presence ofsorsilen or DEAE-cellulose, and 55% of their initial activity respectively was preserved. In the presence of silica gel and CM-cellulose, a decreased rate of lipid hydrolysis by Pseudomonas sp. enzymes was observed in water medium, and the hydrolysis rate increased by 2.4 and 1.5 times respectively in the presence of aminoaerosil and polykefamid. In an aqueous-alcohol medium, aminoaerosil and polykefamid decreased the rate of substrate hydrolysis by more than 30 times. The addition of aerosil to aqueous and aqueous-alcohol media resulted in an increase in the hydrolysis rate by 1.2-1.3 times. Sorsilen stabilized Penicillium sp. lipase activity at 40, 45, 50 and 55 degrees C. Either stabilization or inactivation of lipases was observed depending on the pH of the medium and the nature of chemical groups localized on the surface of solid phase. The synthetizing activity of lipases also changed depending on the conditions.

STUDY OF THE PHOTOPHYSICAL BEHAVIOR AND THE PHOTOSTABILITY OF AN AZLACTONE DERIVATIVE ENCAPSULATED IN CYCLODEXTRIN

The azlactones are well known compounds and are important intermediates in the synthesis of chiral heterocyclic amino acids. Even with high intensities of fluorescence emission, very few studies were found in literature about their photophysical and photochemical properties. Due to the low solubility in aqueous solution, we carried out the photochemical and photophysical study of these compounds in aqueous and hydroalcoholic solution in the presence of cyclodextrins since, according to literature data, the encapsulation can enhance the stability of the encapsulated molecule as well as modify its photophysical properties. The results showed increase of absorption intensity of azlactone after encapsulation in the β-cyclodextrin (b-CD) cavity in aqueous-alcoholic medium, however it is observed the decrease in the photostability azlactone derivative in aqueous-alcoholic medium.

Oxidative phenylamination of 5-substituted 1-hydroxynaphthalenes to N-phenyl-1,4-naphthoquinone monoimines by air and light "on water".

A number of N-phenyl-1,4-naphthoquinone monoimines 6–10 were prepared by on-water oxidative phenylamination of 1,5-dihydroxynaphthalene (1) and 5-acetylamino-1-hydroxynaphthalene (5) with oxygen-substituted phenylamines under aerobic conditions and either solar or green LED radiation, in the presence of rose bengal as singlet oxygen sensitizer. As compared to the conventional oxidative phenylamination procedures, this novel synthetic method offers the advantage of aerobic conditions “on water” instead of hazardous oxidant reagents currently employed in aqueous alcoholic media.

Formation of semiquinone radical anion and free radical scavenging reactions of plumbagin: a pulse radiolysis study

Kinetics and mechanism of scavenging of reducing free radicals by plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) are studied using pulse radiolysis technique. It scavenged superoxide radical, hydroxyethyl radical and hydrated electron with bimolecular rate constants of 8.9 × 107, 2.3 × 109 and 1.6 × 1010 M−1 s−1, respectively in aqueous-alcohol medium. Plumbagin also scavenged linoleic acid peroxyl radical and tyrosyl radical with bimolecular rate constants of 1.0 × 108 and 7.0 × 106 M−1 s−1, respectively. Further, redox properties of plumbagin and its transients are studied using standard redox couples and cyclic voltammetry.