Basic Ethanol Solution Research Articles

Spectral characterization and computational studies of some new synthesized 3-arylazo-4-hydroxybenzo[h]quinolin-2(1H)-one dyes

A series of substituted anilines with different electron releasing and electron accepting substituents have been diazotized and coupled with 4-hydroxybenzo[h]quinoline-2(1H)-one in basic ethanol solution at 0-5°C. The structures of these newly synthesized azo dyes were assigned by IR, 1H NMR and Mass spectroscopic analyses. The UV-vis absorption spectra of the dyes, recorded in solvents with different polarities, showed no distinct change owing to their strong intramolecular hydrogen- bonding interactions. The visible absorption spectra along with 1H NMR findings of all the 4-hydroxyquinolin-2-one dyes revealed that there is a mixture of two geometrical isomers E and Z of keto-hydrazo-keto tautomeric form in the solution state in solvents with different polarities. The effects of acid and base on the visible absorption spectra of the of the dyes in ethanol were also studied and showed that the spectral changes are clearly dependent upon the protonation-deprotonation of the dye molecules. The geometries of the azo and hydrazone tautomeric forms of the dyes were optimized at B3LYP/6-31G(d) level of theory. DFT calculations were employed to calculate the stability of tautomeric forms of prepared dyes both in gas phase and in the solution state and the results agreed well with 1H NMR spectroscopic results.

Native collagen hydrogel nanofibres with anisotropic structure using core-shell electrospinning

Collagen hydrogel is a popular extracellular matrix (ECM) material in regenerative medicine and has an isotropic structure. In contrast, native ECM has an anisotropic structure. Electrospinning of collagen dissolved in organic solvents is widely used for fabricating anisotropic collagen nanofibres; however, such fibres are water-soluble and require cross-linking before use as scaffolds for cell culture. Herein, electrospinning using a core-shell nozzle was employed to spin an aqueous acidic solution of collagen and encapsulate it within a shell of polyvinylpyrrolidone (PVP). Subsequently, the core collagen was gelled, and the shell PVP was washed away using a basic ethanol solution to yield anisotropic collagen hydrogel nanofibres. Immunostaining and Fourier transform infrared spectroscopy revealed that the obtained fibres were composed of collagen, and surface PVP was removed completely. Circular dichroism measurements confirmed that the fibres exhibited the triple helical structure characteristic of collagen. Human umbilical vein endothelial cells cultured on the collagen hydrogel fibres were oriented along the fibre direction. Hence, this method is suitable for fabricating fibrous anisotropic collagen hydrogels without chemical and thermal cross-linking, and can facilitate the development of safe medical materials with anisotropy similar to that of native ECM.

Adsorption property of alizarin red S by NiFe2O4/polyaniline magnetic composite

NiFe2O4/polyaniline (PANI) magnetic composite was prepared by in situ chemical oxidative polymerization of aniline in the presence of NiFe2O4 particles, where the NiFe2O4 particles were synthesized by a facile hydrothermal method. The magnetic composite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area method and vibrating sample magnetometer (VSM) techniques. The adsorption characteristics of the NiFe2O4/PANI composite were assessed by using alizarin red S (ARS) as an adsorbate. The adsorption process was investigated as the function of ionic strength, temperature, solution pH, adsorbent dosage, contact time and initial ARS concentration. The equilibrium adsorption data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 186 mg g−1 at 303 K. The remarkable adsorption capacity of ARS onto NiFe2O4/PANI was attributed to stronger π-π interaction and weak electrostatic attraction between ARS and NiFe2O4/PANI.Kinetic studies indicated that ARS adsorption followed the pseudo-second-order kinetic model. The whole adsorption process was jointly controlled by external mass transfer and intraparticle diffusion. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) revealed that the adsorption of ARS on the NiFe2O4/PANI composite was a spontaneous and endothermic process. Magnetic NiFe2O4/PANI with adsorbed ARS could be regenerated using basic ethanol solution and was separable from liquid media using a magnetic field.

Crystal structure of (2E)-3-[4-(di-methyl-amino)-phen-yl]-1-(thio-phen-2-yl)prop-2-en-1-one.

The equimolar reaction between 4-(di-methyl-amino)-benzaldehyde and 2-acetyl-thio-phene in basic ethano-lic solution yields the title compound, C15H15NOS, whose mol-ecular structure matches the asymmetric unit. The mol-ecule is not planar, the dihedral angle between the aromatic and the thio-phene rings being 11.4 (2)°. In the crystal, mol-ecules are linked by C-H⋯O and weak C-H⋯S inter-actions along [100], forming R22 (8) rings, and by weak C-H⋯O inter-actions along [010], forming chains with a C(6) graph-set motif. In addition, mol-ecules are connected into centrosymmetric dimers by weak C-H⋯π inter-actions, as indicated by the Hirshfeld surface analysis. The most important contributions for the crystal structure are the H⋯H (46.50%) and H⋯C (23.40%) inter-actions. The crystal packing resembles a herringbone arrangement when viewed along [100]. A mol-ecular docking calculation of the title compound with the neuraminidase enzyme was carried out. The enzyme shows (ASN263)N-H⋯O, (PRO245)C-H⋯Cg(thio-phene ring) and (AGR287)C-H⋯N inter-molecular inter-actions with the title compound. The crystal structure was refined as a two-component twin with a fractional contribution to the minor domain of 0.0181 (8).

Room-temperature synthesis of silica supported silver nanoparticles in basic ethanol solution and their antibacterial activity

A facile and environmentally friendly route was developed to synthesize silica supported silver nanoparticles through the reduction of Ag+ ions in basic ethanol solution without adding any other reducing agents or surfactants at room temperature.

Ionic liquid based microextraction combined with derivatization for efficient enrichment/determination of asulam and sulfide

This study reports 2 new simple derivatization-based dispersive liquid-liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively. Beer's law was obeyed in the ranges of 1.0-80.0 and 0.1-5.0 ng mL$^{-1}$ for asulam and sulfide, respectively. Limits of detection for asulam and sulfide determination by the DLLME methods were 0.18 and 0.019 ng mL$^{-1}$, respectively. Various foreign cations, anions, organics, and pesticides were tested to evaluate the selectivity of the DLLME methods. The methods were successfully applied to the determination of asulam and sulfide in various environmental, wastewater, and urine samples.

Novel microwave-synthesis of Cu nanoparticles in the absence of any stabilizing agent and their antibacterial and antistatic applications

For the first time, copper nanoparticles were synthesized under microwave (MW) irradiation in the absence of any stabilizing agent. A 2-step synthetic approach was adopted working in basic ethanol solution and then ascorbic acid was added as a reducing reagent in the second step. The obtained copper nanoparticles were characterized by UV–vis spectroscopy, XRPD and TEM analysis. UV–vis spectra show an absorption peak at about 580–590nm, typical of the plasma resonance of copper nanoparticles and XRPD analysis reveals that the complete reduction to metallic copper was reached at the end of the second step. Average sizes in the range 7–15nm were ascertained through TEM microscopy. These copper nanoparticles are suitable for antibacterial and antistatic applications. The bactericidal effect was investigated in relation to the diameter of inhibition zone in disk diffusion tests on calf crust leather sample and an interesting antibacterial activity was verified against both Gram positive and Gram negative bacteria (Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Candida albicans). Moreover, this treated leather showed encouraging antistatic behavior: in particular, equivalent circuital parameters were estimated via an impedance spectroscopy technique to have a first evaluation of the charge dissipation activity by volume conduction.

C–H⋯Cl relevant discrepancy on structure, magnetic and electronic conductivity of two mixed-valence Cu ICu II coordination polymers

Two mixed-valence Cu ICu II coordination polymers [Cu ICu II(qdiol)ClL] n (qdiol 2−=2,3-dioxyquinoxalinate, L=2,2′-bipyridine, 1; L=1,10-phenanthroline, 2) were obtained in basic ethanolic solution of CuCl 2, 1,4-dihydro-2,3-quinoxalinedione and L under the solvothermal condition. 1 and 2 are similar in composition, but differ remarkably in structure. The coordination modes of Cu II, qdiol 2− and L are identical in both complexes. But the Cu I ions are two- and three-coordinated, and the Cl − ions are terminal and bridging, in 1 and 2, respectively, which are relevant to the significantly different C–H⋯Cl hydrogen bonding pattern of bpy and phen. The temperature variable magnetic susceptibilities show that 1 is paramagnetic and 2 is weakly antiferromagnetic. The complex impedance spectroscopic studies indicate that both 1 and 2 are semiconductors and 2 is more conducting.

Large Stokes‐Shift Fluorescent Silica Nanoparticles with Enhanced Emission Over Free Dye for Single Excitation Multiplexing

AbstractWe describe a polycondensation reaction of silica precursors in a modified Stöber‐type basic ethanol solution to produce graded Stokes‐shift core‐shell silica nanoparticles providing bright and spectrally multiplexed sets of fluorescent tags that are excitable using a single excitation source. Dynamic light scattering and scanning electron microscopy demonstrate particle sizes in the sub‐10 nm regime. Absorption matched emission comparisons between encapsulated and free dyes in aqueous solution reveal about an order of magnitude per‐dye brightness enhancements that are apparent by simply looking at the solutions under laser illumination conditions.magnified image

Structural analysis and electronic properties of a homodinuclear erbium(III) complex bridged by the polyazine ligand 2,2′-bipyrimidine

Abstract Structural analysis of the previously reported homodinuclear complex [Er(tfa)3]2bpm (where tfa = 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione and bpm = 2,2′-bipyrimidine) synthesized by reaction of two equivalents of ErCl3 with six equivalents of tfa and one equivalent of bpm in a basic ethanol solution is presented. X-ray quality crystals were grown by slow evaporation of concentrated methanol solution containing the complex. The complex crystallizes in the monoclinic space group P21/n, with a planar bpm ligand. The erbium…erbium distance is 6.715(5) A. Each erbium center is eight coordinate from six tfa oxygens and two bpm nitrogens. Electronic transitions of concentrated solutions of the complex reveal three sharp lines corresponding to the 4f–4f∗ transitions at 486 nm, 520 nm and 657 nm with the lowest energy transition corresponding to 4I15/2 → 4F9/2.

Supramolecular isomerism in the hydrogen-bonded network of (5R,10R)-3,8-dihydroxy-5,10-diethoxy-5,10-dihydrochromeno[5,4,3-cde]chromene monohydrate

A new compound (5R, 10R)-3,8-dihydroxy-5,10-diethoxy-5,10-dihydrochromeno[5,4,3-cde]chromene monohydrate was obtained from 3,4-dihydroxybenzaldehyde in aerobic basic aqueous ethanol solution in the presence of manganese chloride and triethylamine and crystallized in orthorhombic P212121 space group (denoted as 1). When 1 was recrystallized from aqueous methanol, it was transformed to another crystal (2) with the same composition but in P21/n space group. The drastic difference in the extensive hydrogen bond network makes 1 a 3D and 2 a 2D infinite supramolecular structure, respectively.

In Situ Growth of ZnO Nanocrystals from Solid Electrospun Nanofiber Matrixes

Porous fiber membranes consisting of 1D assemblies of ZnO nanocrystal-supported poly(vinyl alcohol) (PVA) nanofibers are described. These hybrid nanofiber membranes were assembled by first electrospinning a ZnO precursor-containing PVA aqueous solution. Subsequently, the electrospun composite nanofibers were submerged in a basic ethanol solution. As a result, ZnO precursors in solid PVA matrixes were hydrolyzed to generate ZnO crystals residing on the fiber surfaces. Photoluminescence spectroscopy analysis demonstrated the as-hydrolyzed fiber membranes possess white luminescence. Furthermore, the ZnO-encapsulated PVA nanofibers were prepared by directly electrospinning a ZnO nanocrystal-containing PVA solution as the contrast of the as-hydrolyzed hybrid nanofibers. The surface photovoltage spectroscopy (SPS) confirmed that the as-hydrolyzed hybrid fiber membranes had a strong SPS response, but the directly spun fiber membranes did not have any SPS response. This can be attributed to the favorable structure of the hydrolyzed hybrid nanofibers, that is, the surface residence of ZnO permits ZnO crystals to make direct contact with ITO electrodes to transfer the photogenerated electron originating from ZnO to ITO electrodes. By contrast, the transfer of the photogenerated electron is limited by PVA matrixes in the directly spun fiber system.

SYNTHESIS OF ALKYL AND ARYL 1-PROPENYL ETHER MONOMERS: A NEW APPROACH

A new, convenient synthesis of alkyl and aryl 1-propenyl ether monomers in good to excellent yields has been developed. Alkyl and aryl allyl ethers can be smoothly isomerized to the desired 1-propenyl ethers by refluxing in a basic ethanolic solution containing pentacarbonyliron as a catalyst. A simplified two-step, one-pot procedure has also been developed which consists of combining an alcohol with allyl bromide in the presence of base and then adding pentacarbonyliron to isomerize the in-situ generated allyl ether to directly give the 1-propenyl ether. Good yields of alkyl 1-propenyl ethers were obtained using this process. Factors affecting the isomerization reaction were investigated and a mechanism was proposed.

テトラエチレンペンタミン系含リンキレート樹脂担持貴金属触媒の調製

Noble metal catalysts supported on diphenyl phosphonate7formaldehyde chelate resin with tetraethylenepentamine (DPP-TEP) were prepared.The gold, platinum, and palladium ions adsorbed on DPP-TEP were easily reduced by sodium borohy dride in basic ethanol solution under reflux for about 20 min to give metallic gold, platinum, and palladium supported on resin. The noble metal catalysts supported on resin could be used at 300°C several times.The catalytic activities of noble metals supported on resin for the hydrogenation of alkene increased in the order: gold catalyst < palladium catalyst < platinum catalyst. Using the platinum catalyst in the hydrogenation of alkadienes, propadiene and 1, 3-butadiene were converted to the corresponding alkanes quantitatively at 50 °C. Using the palladium catalyst, propadiene and 1, 3-butadiene were converted to propylene (90%) and 1-butene (80%) at 50°C respectively.

Dinuclear Cu(II) complexes with two pyrazolate bridging groups formed from 26 membered oxaimine and polyamine macrocycles of 3,5-disubstituted 1 [formula omitted]-pyrazole

The deprotonation in basic ethanolic solution of the 26 membered pyrazole derived macrocyclic Schiff base 1 and polyamine 3 affords dipyrazolate salts ( 1′ and 3′) from which dinuclear Cu(II) complexes ( 2 and 4) have been obtained. The X-ray crystallographic analysis of 4 demonstrates that inside the macrocyclic cavity, the two pyrazolate rings are simultaneously acting as exobidentate ligands linking both metal cations, the CuCu separation being 3.9 Å.

ChemInform Abstract: Photochemical C‐P Bond Cleavage of Benzoylbenzylphosphonic Acids.

AbstractThe benzoylbenzylphoshonic acids (I) undergo photochemical P‐C bond cleavage in a basic ethanolic solution to yield the methylbenzophenones (II), together with orthophosphate and ethyl phosphate.

ChemInform Abstract: Nitrogen Bridgehead Compounds. Part 70. Studies on Quinolizine Derivatives. Part 4. Ultraviolet‐Visible Spectra and Chemical Properties of Some Quinolizine Derivatives and Their Monocyclic Tautomers.

Ultraviolet-visible spectra of 4-oxo 1 and 4-imino 2 quinolizines or their monocyclic tautomers 3, 4 have been studied in neutral, acidic and basic ethanolic solution as well as in dimethyl sulfoxide and chloroform. Ring B of 4-oxo and 6-unsubstituted 4-imino compounds can be cleaved by sodium ethanolate more or less easily. Ring B of 6-methyl-4-iminoquinolizines is very unstable and they are present mainly in the monocyclic form which are partly dissociated in ethanol and dimethyl sulfoxide especially in higher dilution or in the presence of sodium ethanolate. In dilute acidic ethanol or chloroform, the dissociation is suppressed and in the latter solvent and in some cases, absorption bands can be observed due to a small amount of the 4-imino-6-methylquinolizines. In acidic solution of compounds 3B=C, 3D, 4E, 4F=G having simultaneously cyano and ethoxycarbonyl groups in 1 and 3 position, not simple reprotonation occurs but irreversible changes can be observed.

PHOTOCHEMICAL C[sbnd]P BOND CLEAVAGE OF BENZOYLBENZYLPHOSPHONIC ACIDS

Abstract Benzoylbenzylphosphonic acids (p- and m-) easily underwent photochemical C[sbnd]P bond cleavage in a basic aqueous ethanol solution to give methylbenzophenone, orthophosphate, and ethyl phosphate.

Nitrogen bridgehead compounds. Part 70. Studies on quinolizine derivatives. Part 4. Ultraviolet‐visible spectra and chemical properties of some quinolizine derivatives and their monocyclic tautomers

AbstractUltraviolet‐visible spectra of 4‐oxo 1 and 4‐imino 2 quinolizines or their monocyclic tautomers 3, 4 have been studied in neutral, acidic and basic ethanolic solution as well as in dimethyl sulfoxide and chloroform. Ring B of 4‐oxo and 6‐unsubstituted 4‐imino compounds can be cleaved by sodium ethanolate more or less easily. Ring B of 6‐methyl‐4‐iminoquinolizines is very unstable and they are present mainly in the monocyclic form which are partly dissociated in ethanol and dimethyl sulfoxide especially in higher dilution or in the presence of sodium ethanolate. In dilute acidic ethanol or chloroform, the dissociation is suppressed and in the latter solvent and in some cases, absorption bands can be observed due to a small amount of the 4‐imino‐6‐methylquinolizines. In acidic solution of compounds 3B=C, 3D, 4E, 4F=G having simultaneously cyano and ethoxycarbonyl groups in 1 and 3 position, not simple reprotonation occurs but irreversible changes can be observed.

Liquid Chromatographic Determination of Basic Nitrogen-Containing Polynuclear Aromatic Hydrocarbons in Smoked Foods

Several smoked foods were analyzed for basic nitrogen-containing polynuclear aromatic hydrocarbon (NPAH) content by a relatively rapid liquid chromatographic (LC) technique. The analyzed products included both domestic and imported market basket commodities. Nanogram quantities of NPAH standards were detected by UV and fluorescence detectors connected in series. The NPAHs were extracted from basic aqueous ethanolic solution into cyclohexane, extracted from cyclohexane into 6N HCl, and extracted back into cyclohexane after neutralization of the acid. The NPAHs were then purified by filtering the extract through deactivated basic alumina. The eluate from this step was concentrated to dryness, and the residue was dissolved in 95% ethanol and analyzed by LC, using a Vydac C-18 column and acetonitrile-water (9 + 1) as the mobile phase. Recoveries of 3 NPAHs, 5,7-dimethylbenz(a)acridine, dibenz(a,j)acridine, and dibenz(a,h)acridine, each added to salmon and sausage at the 5 ppb level, ranged from 62 to 101% by fluorescence measurement and from 64 to 106% by UV measurement. None of the NPAHs used as standards were found by either fluorescence or UV detection at levels greater than or equal to 5 ppb in any of the foods analyzed.