Copper-cysteamine nanoparticles encapsulating fluorocoumarin silicon(IV) phthalocyanines: synthesis,characterization, and photophysical properties

Abstract

Three nanohybrid materials (FCSiPc@PEG-Cu-Cy) using poly (ethylene glycol) copper-cysteamine (PEG-Cu-Cy) nanoparticles as a carrier to load three fluorocoumarin silicon(IV) phthalocyanines (FCSiPcs) were prepared. The morphologies of these nanohybrids were characterized by transmission electron microscopy (TEM). The interactions between PEG-Cu-Cy nanoparticles and three FCSiPcs were studied by UV/Vis and fluorescence spectroscopic methods. The photophysical and photochemical properties of these FCSiPcs were influenced by PEG-Cu-Cy nanoparticles and exhibited substituents dependent of phthalocyanines in nanohybrids. The fluorescence resonance energy transfer (FRET) occurred from FCSiPcs (donors) to PEG-Cu-Cy nanoparticles (acceptors). These nanohybrids may be potential photosensitizers for photodynamic therapy.     

Carrier‐Mediated Transport of Hg(II) through Bulk and Supported Liquid Membranes

The transport of Hg (II) ions from an aqueous solution into an aqueous receiving solution through bulk and supported liquid membranes containing a calix[4]arene derivative 1 as a carrier was examined. The kinetic parameters of bulk liquid membrane studies were analyzed assuming two consecutive, irreversible first‐order reactions. The influence of temperature, stirring rate, carrier concentration and solvent on the kinetic parameters (k₁, k₂, R_m ^max, t_max, J_d ^max, J_a ^max) has also been investigated. The membrane entrance rate, k₁, and the membrane exit rate, k₂, increased with increasing temperature and stirring rate. The activation energy values are calculated as 4.87 and 48.63 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species. Also, the transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet supported liquid membrane has been investigated by the use of calix[4]arene derivative 1 as carrier and Celgard 2500 as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyloctyl‐ether (NPOE) solvent and the influence was found to be in the order of NPOE>chloroform>xylene.     

Diels–Alder Cycloadditions of 1,2-Dihydrophosphinine Oxides and Fragmentation-Related Phosphorylations with 2-Phosphabicyclo[2.2.2]Octadiene Oxides Under Green Chemical Conditions—The Role of Microwave and Ionic Liquids

Abstract

The effect of the use of microwave (MW) and solvents including ionic liquids on the Diels–Alder reaction of 1,2-dihydrophosphinine oxides (1) and fragmentation-related phosphorylation of phenols with 2-phosphabicyclo[2.2.2]octadiene oxides (4) was studied. The MW-assisted Diels–Alder reaction of dihydrophosphinine oxides (1) with N-phenylmaleimide may be advantageous to carry out in [bmim][BF₄] due to shorter reaction times, but the dimerization of the double-bond isomers (A and B) of the dihydrophosphinine oxides (1) may be best accomplished under MW in the absence of any solvent. The fragmentation-related phosphorylations may also be carried out under MW, which with the P-phenyl precursor (4a) became more efficient in [bmim][BF₄].

GRAPHICAL ABSTRACT      

Unusual regioselective acylation of the primary hydroxy groups of β-cyclodextrin

The reaction of -cyclodextrin (1) with palmitoyl (2) and valeryl (4) chlorides in DMF or Py, unlike previously studied acetylation of 1, involves only the primary hydroxy groups of 1. The outcome of the reaction depends on the reaction conditions and the nature of the acid scavenger used (Et₃N, Prⁱ ₂NEt, PhNMe₂, Py). ¹³C NMR spectroscopy was shown to be an effective tool in determining the number and position of aliphatic carboxylic acid residues introduced into 1. A hypothesis stating that preliminary formation of a reactive inclusion complex (acid chloride1) is required for the acylation of 1 to occur is proposed and substantiated. This hypothesis provides a unified explanation for a variety of unusual facts observed in the acylation of 1 and its derivatives.     

STUDIES OF MECHANISM OF 2-METHYLTHIOPHENE AND THIOPHENE FORMATION FROM N-PENTANE AND HYDROGEN SULPHIDE USING 14C

Abstract

The mechanism of 2-methylthiophene formation from n-pentane and hydrogen sulphide over Cr-containing oxide catalyst is studied by using the Kinetic-Isotope method. The experiments were carried out in pulse system in He as a carrier gas (535° and 3 atm.) using ¹⁴C-labelled pentene and n-pentane. The reaction products were analyzed by radiochromatography. It is shown the 2-methylthiophene formation from n-pentane and hydrogen sulphide proceeds largely via consecutive dehydrogenation of n-pentane to pentenes, pentadiene followed by interaction with hydrogen sulphide. Thiophene is largely as a result of C₄-hydrocarbon interaction with hydrogen sulphide. A general scheme of the mechanism of 2-methylthiophene and thiophene formation is suggested.     

A Chain Catalytic Reaction Involving Pd Cluster as Chain Carrier

   α−Alkyl- and α,α′-dialkyl-substituted benzylic alcohols PhCR′R′′OH (R′=H, Me, Et, Bu; R′′=H, Me) are transformed to the corresponding dilbenzylic ethers and water in acid-free neat substrate media shortly after the addition of the palladium(I) cluster [Pd₄(CO)₄(OAc)₄] (1). During the catalytic reaction occurring under anaerobic conditions, cluster 1 is gradually decomposed to form Pd black, whereas neither original cluster 1 nor Pd black is responsible for the observed reaction. The true reaction catalyst is generated from cluster 1 after a short induction period. On the basis of the reaction kinetics and the HREM, X-ray diffraction, DTA-TG, and elemental analysis data, the catalytic dehydration is suggested to occur through a nonradical chain mechanism involving an unstable intermediate Pd cluster as the chain carrier.

Beiträge zur Chemie der Pyrrolpigmente, 78. Mitt.: Die Eigenschaften desb-Nor-bilatrien-abc-b-Nor-biladien-ac-Systems

The redox coupleb-nor-biladiene-ac (2)/b-nor-bilatriene-abc (3) exhibits an oxidative half wave potential of 800 mV in acetonitrile solution. It is demonstrated that it can be used as an extremely efficient electron carrier through bulk membranes. Whereas2 is not suitable as a ligand in carrier mediated cation transport,3 is a medium suited carrier for Cu(II) or Zn(II) ions, however, it is the most efficient one found so far for transport of Hg(II) ions. A 1:1 zinc chelate of3 is isolated and characterized. it is deduced to represent a polymer consisting of about 73 monomer units.

     

Energetics of model compounds of water oxidizing complex containing quinone cofactors

To reveal reaction mechanism of PS-II, the reaction products of photolysis may be compared with their thermolytic products. According to required molecular assemblies in manganese clusters at WOC of PS-II, we have strategically synthesized dimers (M-1, M-2), trimers (M-3A, M-3B) and tetramer (M-4) using spin carrier imino-phenol functionalized ligands viz. Lawsone Oxime (L-1) and Phthiocol Oxime (L-2) of naturally occurring quinones .These are characterized by elemental analyses, thermogravimetric analyses, differential thermal analyses, powder X-ray diffraction and infrared spectroscopy. Stabilization energies for molecular associations of ligands in various redox and stereoisomeric forms via hydrogen bondings are compared with thermal energies required for their expulsion from the coordination polymers calculated with the help of Coats and Redfern’s relation of rising temperatures. Activation energy required for establishing tetramer (M-4) and dimer (M-2) in coordination sphere by counter ion using same synthetic route is found to be comparable (~37.48±1 kJ mol^-1). Quantitized energies from TG-DTA data for valence tautomers of redox active ligands play significant role in formation of resultant model compound. viz. tetramer, dimer of dimer and trimer. The role of oxo, acetato and spin carrier ligands in model cluster compounds are proposed with respect to their expulsion energies.     

Indirect Catalytic Spectrophotometric Determination of Metamizol Following Oxidation by Lead Dioxide Immobilized in A Polyester Resin Bed

Abstract

A spectrophotometric-indirect procedure for the determination of metamizol is described. The method is based on the reaction of the drug in a solid-phase (lead dioxide immobilized in a polyester resin bed) in acidic media (perchloric acid 0.01 M as carrier). The lead dioxide reactor provides simultaneously an effective oxidation of the drug and a controlled liberation of Pb(II) which acts as catalyst on the reaction pyrogallol red-potassium persulphate; the oxidation of the red pyrogallol results in a less coloured solution. The decreased red colour (negative FIA peaks) is monitored at 520 nm. The calibration graph is linear in the interval 2–16 ppm in metamizol. The relative standard deviation for the determination of 10.4 ppm of metamizol is 2.9% (n=23) and the sample throughput is 72 h^?1.     

Comparison of Aqueous,Micellar and Microemulsion Carriers in Flow Injection Analysis. The Base Hydrolysis of Acetylsalicylic Acid

Abstract

The potential applicability of surfactant solutions as carrier streams in flow injection analysis is examined. The reaction rates determined for the base catalyzed hydrolysis of acetylsalicylic acid in aqueous, micellar and microemulsion solutions show a rate enhancement of 40% for the static microemulsion system when compared to the aqueous solution. However, when the identical microemulsion solution is employed as a carrier stream in flow injection analysis with ultraviolet detection, this enhancement in rate is not observed. To our knowledge, all previous work employing microemulsions in FIA has been concerned only with detection enhancement, here we present direct comparisons between aqueous and microemulsion carriers concerning rates of reaction, peak dispersion and analytical figures of merit. The loss in relative sensitivity can be traced to the increased dispersion in the microemulsion system (D = 14.36) when compared to the aqueous carrier (D = 12.52). Additionally, an increased skewness was observed in the peaks obtained with a microemulsion carrier, yielding further information about the physical dispersion process occuring in the sample plug.     

Study on CuO/Al2O3 catalytic ozone treatment of acid red B solution

A CuO/Al₂O₃ catalyst was prepared using the impregnation method. The catalytic activity of CuO/Al₂O₃ for the ozonation of acid red B (ARB) in aqueous solution was studied, the chemical oxygen demand (COD) removal rate was an indicator for catalytic activity evaluation. The effects of initial ARB concentration, solution pH, and different oxidative degradation systems on oxidative degradation of ARB solution were studied. The CuO/Al₂O₃ catalyst was characterized using X‐ray diffractometry (XRD), N₂ adsorption desorption test, X‐ray photoelectron spectroscopy (XPS), and zero‐point charge (pH_zpc). The results show that copper species on the carrier were in the form of CuO and highly dispersed on the carrier. CuO can increase the alkalinity of the Al₂O₃ surface, and the CuO/Al₂O₃ catalyst facilitates the decomposition of O₃ into ·OH, which was beneficial for the catalytic O₃ oxidation degradation reaction. With the increase of the initial concentration of simulated wastewater, the CuO/Al₂O₃ catalytic reaction still has a high COD removal rate. Alkaline solution was of benefit to catalyze the degradation of ARB solution. When the ARB solution pH = 8.93, the degradation reaction was carried out for 40 min, the COD removal rate reached 83.2%. The degradation reaction was dominated by the hydroxyl radical (·OH) reaction.     

Selective Determination of Cytosine Based on Its Fluorogenic Reaction with Triethylamine/Chloroacetonitrile

Abstract

A sensitive fluorometric method is described For selective determination of cytosine in nucleobases. The method is based on chemical derivatization of cytosine by triethylamine/chloroacetonitrile. The effects of solvent, reaction temperature, reaction time and concentration of reagents on the efficiency of the reaction were studied. A good linear relationship between fluorescence intensities and cytosine concentrations in the range of 2.0–800 ng/mt was observed. The detection limit for cytosine is 0.6 ng/ml (S/N=3). The relative standard deviations (7 replicates) for measurements of 50 and 500 ng/ml cytosine were 2.1 and 2.5%, respectively.     

Carboxylic Acids Promoted Speier’S Catalyst for the Hydrosilylation of Styrene with Triethoxysilane: Activity,Selectivity, and Mechanism

Abstract

Catalytic performances of Speier's catalyst with carboxylic acids were studied in the hydrosilylation reaction of styrene with triethoxysilane. The effect of carboxylic acids (RCOOH) with different pKa values and size was investigated, and the temperature and n(COOH)/n(Pt) ratios were also studied. The catalytic activity of the hydrosilylation reaction is related to the acid strength of the carboxylic acid, temperature, and n(COOH)/n(Pt) ratio, while the selectivity for the β-adduct is related to the size of carboxylic acid and the n(COOH)/n(Pt) ratio. Moreover, the influence of carboxylic acid on the hydrosilylation reaction was explained with the help of density functional theory calculations, and a reasonable mechanism was proposed.     

REACTION OF BIS-[DIALKOXYPHOSPHORYL]- AND BIS-[DIALKOXYTHIOPHOSPHORYL]- DISULFIDES WITH TRIALKYLSILYLCYANIDES NEW ROUTE TO DIALKYLPHOSPHORO- AND DIALKYLTHIOPHOSPHORO THIOCYANIDATES AND O,O,O,O-TETRAALKYLPYROPHOS- PHOROTRITHIOATES

Abstract

The reaction of organophosphorus disulfides with trialkylsilylcyanide has been investigated. It provided direct evidence for the intermediacy of thiocyanidate >P(X)SCN, X=O, S in this type of reaction. The disulfides studied involved phosphoryl, phosphonyl and/or phosphinyl disulfides. They have been shown to follow the common mechanism. The studied reaction of thiophosphoryl disulfides with trimethylsilylcyanide represents a new and highly efficient route to tetraalkylpyrophosphoro-trithioates.     

Electro-migration on paper in the separation of ions

Summary Cu-Cd can be electrophoretically separated with hydrochloric acid as the carrier electrolyte. Neither the concentration of the ion studied nor the presence of other cations has any effect on the movement of the ion. Direction of the movement and the size of the migration zone depend upon the ion to be electrophorised and the concentration of hydrochloric acid, the carrier electrolyte.Part VIII: cf. Z. anal. Chem. 159, 287 (1957/58).     

Stability of Oligomeric α-Alkoxyhydroperoxides

The thermal decomposition of oligomeric -alkoxyhydroperoxides (I) is described by a first-order rate law and characterized by an activation energy equal to 19.7 kJ/mol. A chain mechanism and a rate law for this reaction are proposed. The effect of amine and phenolic stabilizers on decomposition is studied, the efficiency of phenolic stabilizers is examined, and the effective rate constant of the acid-catalyzed decomposition of compounds I is determined.     

Synthesis of Carboxymethyl Cellulose Based Drug Carrier Hydrogel Using Ionizing Radiation for Possible Use as Site Specific Delivery System

A unique natural polymer based colon specific drug carrier was prepared from carboxymethyl cellulose (CMC) and acrylic acid (AAc) in aqueous solution employing γ‐radiation induced copolymerization and crosslinking. The effect of preparation conditions such as the natural polymer content and irradiation dose on gelation process was investigated. The swelling behavior of the prepared hydrogels was characterized by investigating the time and pH dependent swelling of the (CMC/AAc) hydrogels of different CMC content. The effects of the hydrogel composition and pH of the swelling medium on the swelling indices were estimated. The results show that the increment in the CMC content in the feed solution enhances the gelation process. The results also show the dependence of the swelling indices on both hydrogel composition and pH value of the swelling medium. To evaluate the ability of the prepared hydrogel to be used as a colon‐specific drug carrier, the release profile of theophylline was studied as a function of time at pH 1 and pH 7.     

Study of Microwave Irradiation Polymerization in the Presence of Different Carriers

ABSTRACT

The influence of the presence of an inorganic carrier in the polymerization systems was investigated in this paper. Ten polymerization systems that contained different inorganic carriers such as Al₂O₃, SiO₂ were studied. The ten polymerization systems are dibutyltin Maleate (DBTM) and allyl thiourea (AT), DBTM and stearic acid vinyl ester (SAVE), SAVE and maleic anhydride (MH), SAVE and acrylamide (AM), itaconic acid (IA) and AM, SAVE and IA, AM and MH, IA, sodium acrylate (AANa), AM. It was found that the activity of monomer can be changed in the presence of a carrier and furthermore, the different species of carrier influence the activity of same monomer differently in the polymerization.     

Effect of Carbonaceous Carrier and Promoter on Electrocatalytical Properties of Composite Cathodes in Fuel Cells with Alkaline Electrolyte

The activity of composite catalysts, Pt and Co-porphyrin- or Fe-phthalocyanine-based pyropolymers on low-disperse carbonaceous carriers (graphite, carbon black), in the oxygen and H₂O₂electroreduction in 1 M KOH is studied. Kinetic parameters of oxygen electroreduction are determined from experiments with rotating disk and model floating electrodes. Possible mechanism of the oxygen electroreduction reaction is discussed; it includes a slow stage of attachment of the second electron on the pyropolymer/carbonaceous carrier or joining the first electron (under the conditions of Temkin adsorption) on the platinum/graphite catalysts.     

OLEFIN SYNTHESIS USING LITHIUM DERIVATIVES OF N,N,N',N'-TETRAMETHYLDIAMIDES OF ARYLMETHANEPHOSPHONIC ACIDS

Abstract

The reaction of lithium derivatives of N,N,N',N'-tetramethyldiamides of arylmethanephosphonic acids (1-Li) with aldehydes 2 is studied. It is found that under certain reaction conditions (THF, 5 hrs at -70°C and then allowing to warm to room temperature) the aldol stage of the reaction is highly stereoselective, only erythro adducts (2-hydroxyphosphonamides) 3, 4 being formed in 47–75% yields. By heating of 3 and 4 in neutral medium the corresponding (Z)-olefins 5, 6 are obtained (yields 64–74%). It is established that an acid catalyzed olefination of 2-hydroxyphosphonamides is also possible, but the reaction is not stereospecific.