The high molecular weight phosphazene random copolymer {[NP(OC6H5)2]0.94 [NP(OC6H5)(OC6H4CNFe(dppe)Cp)]0.06[PF6]0.06}n (1), that carries [Fe(dppe)Cp] cationic fragments coordinated to nitrile side groups, has been synthesized from the copolymer {[NP(OC6H5)2]0.94[NP(OC6H5)(OC6H4CN)]0.06}n and the complex [Fe(CH3CN)(dppe)Cp][PF6] by the complete elimination of the acetonitrile from the equilibrium mixture that they form in dichloromethane solution. The new polymer has been fully characterized by a detailed discussion of the IR and NMR data that may be also useful for the study of other polymeric complexes with similar metal fragments. The cyclic voltammogram of (1) showed an oxidation process that is chemically irreversible but, rather unexpectedly, electrochemically reversible. All the results were interpreted by comparison with the data obtained for the new cyclic model complexes {N3P3(OC6H4-R)5[OC6H4CNFe(dppe)Cp]}[PF6] R=H (2a), But (2b), (see chart 1) that were synthesized by a similar method using the nitrile phosphazene ligands [N3P3(OC6H4-R)5(OC6H4CN)]
the influence of a nonionic surfactant compound (sorbitan monooleate) on the coupled transport of Cu(II) ions in a hollow fiber-type solid supported liquid membrane extractor was studied. The acid compound 5-nonylsalicylaldoxime was used as carrier extractant. The experimental results indicate that the surfactant presents a remarkable interfacial activity, higher than those shown by the carrier extractant which would adsorb at the inteface too. From the experimental results it were calculated for the surfactant the interfacial area occupied by mol, the adsorption equilibrium constant and their critical micelle concentration. Results of extraction equilibrium experiments indicate that Span-80 itself did not extract copper and that Cu(II) extraction is enhanced as the acidity of feed aqueous solution decreases. It was found that the surfactant accelerates the permeability of metal in runs carried out using a higher concentration of Span-80 and when a pH value of 2.5 was adjusted for feed solution. In such condition transport rate of metal through liquid membrane would be controlled by the diffusion of chemical species in it. Furthermore, apparent permeability of copper is enhanced when the content of extractant at liquid membrane is augmented. A preliminary simplified mechanism of metal permeation through the liquid membrane is proposed. The mechanism is based on an heterogeneous interfacial reaction accelerated in the presence of the nonionic surfactant
The oxidation product of the binuclear copper (I) complex Cu2L(ClO4)2 (L = N,N'-bis-(6-methyl-2-pyridil) (2'-pyridyl)methyl m-xylylidene imine) has been isolated and structurally characterised. In the cupric species, [Cu2L(Me-O)2](ClO4 )2, the metal centres are bridged by two methoxide groups, and the oxygenation of the xylyl spacer of the hexadentate ligand is not observed. The copper(I) complex was found to be a catalyst for the oxidation of 3,5-ditertbutylcatechol to 3,5-ditertbutyl-o-benzoquinone by molecular oxygen
The electrochemical behavior of two representative 2,3-dihydro-7H-dibenzo[de,h]quinolin-7-ones was determined using cyclic voltammetry in DMSO as solvent and rationalized by quantum chemical calculations using ab initio and DFT methods. The ESR spectra of the radicals obtained by electrolytic reduction were characterized and analyzed. Calculations at the HF/3-21G and DFT-B3LYP/6-311++G** levels were carried out to obtain the optimized structure, hyperfine coupling constants and to determine the values and to visualize the LUMO and SOMO energy levels, respectively. The calculated electron affinities are in agreement with the reduction potentials measured for both heterocyclic compounds
La Acrilamida puede ser polimerizada usando nuevos sistemas catalizadores. Estos son basados en complejos de renio como fotosensibilizadores usando trietilamina (TEA). La espectroscopia de Resonancia de Espin Electronica fue utilizada para la deteccion de especies radicalarias las cuales fueron formadas en el proceso de polimerizacion. Ademas, se emplearon las tecnicas de Spin Trapping para confirmar la presencia del radical acrilamida. Calculos AM1 e INDO fueron utilizados para calcular las constantes hiperfinas teoricas de radical acrilamida. Los resultados estan de acuerdo con un proceso ciclico en el cual la TEA es un agente donor de electrones que reacciona con el complejo de renio excitado. En este sistema, se postula la presencia de la especie excitada [Re(II)(CO)3L.-(CF3 SO3)]* en la polimerizacion catalitica de acrilamida
Resinas Urea Formaldehido se sintetizaron en un proceso de dos etapas, con diferentes relaciones molares Formaldehido / Urea que fluctuaron entre 1.10 y 1.40. El comportamiento termico del curado de las resinas se estudio mediante Calorimetria Diferencial de Barrido (DSC) bajo diferentes condiciones ambientales. Los termogramas DSC muestran que las reacciones principales de entrecruzamiento de la resina UF con NH4 Cl como catalizador se producen en la zona de los 100oC , especialmente para las que presentan menores proporciones molares de formaldehido. Las resinas sin catalizador o con altas proporciones molares de formaldehido se entrecruzan a temperaturas sobre los 120oC y estas reacciones se prolongan hasta los 180oC
Reaction of the dinuclear complex [{(eta(5)-C5Me5)RhCl}(2)(mu-Cl)(2)] with the chiral phosphine (R)-Ph2PCH2CHMeCH2OH leads to the complex [{(eta(5)-C5Me5)RhCl2(eta(1)-Ph2PCH2CHMeCH2OH-P)}](1). This reaction, in the presence of AgBF4, yields the cationic compound [{(eta(5)-C5Me5)RhCl(eta(2)-Ph2PCH2CHMeCH2OH-P,O)}]BF4 (2). Variable-temperature H-1 NMR and circular dichroism experiments support the stereoselective eta(2)-chelate coordination of the ligand and the proposed configuration for the metal centre. In a similar way, the reaction of the dimer [{(eta(6)-C6Me6)RuCl}(2)(mu-Cl)(2)] with the ligands (R)- and (S)-Ph2PCH2CHMeCH2OH afford the neutral complexes [(eta(6)-C6Me6)RuCl2{eta(1)-PPh2CH2CHMeCH2OH-P}] [R-ligand (3), S-ligand (4)], which in turn react with AgBF4 to give the cationic compounds [(eta(6)-C6Me6)RuCl{eta(2)-PPh2CH2CHMeCH2OH-P,O}]BF4 [R-ligand (5), S-ligand (6)]. All complexes have been characterised by elemental analysis, IR and multinuclear NMR spectroscopies.
En este articulo se presenta en forma concisa e ilustrativa el Metodo Combinatorial de Polya y su aplicacion en la enumeracion de isomeros substitucionales. En particular, dos compuestos organicos policlorados han sido estudiados: los policloronaftalenos (PCN) y los policlorobifenilos (PCB). Estos ultimos constiutyen un buen ejemplo para mostrar como trabaja el metodo en moleculas que presentan rotacion libre interna
Complex [Mo(NHNPh2) (NNPh2)Br-2 (acac)], acac=acetylacetonate, reacts in acetonitrile with 1,1 0-phenanthroline, o-phen, and 2,2'-bipyridine, bpy, to afford complexes [Mo(NNPh2)(2) Br-2 (o-phen)], I, and [Mo(NNPh2)(2) Br-2 (bpy)], II. These complexes have been characterized by IR, UV-vis and H-1 NMR spectroscopies, and elemental analysis. The structure of complex I was solved by single crystal X-ray diffraction. The metal center has a distorted octahedral environment in which the diphenylhydrazido(2-) ligands occupy mutually cis positions but trans to the nitrogen atoms of the o-phen ligand. The bromo ligands occupy mutually trans positions.
El estudio evaluo alternativas metodologicas de extraccion y analisis de tribromofenol desde diversas matrices ambientales. Tambien, tuvo como proposito avanzar en la caracterizacion fisico-quimica del compuesto. Respecto de los niveles de recuperacion obtenidos en matriz de aserrin, se pudo establecer que la mayor recuperacion de tribromofenol se logra con extractor Soxhlet, seguido de ultrasonido y centrifugado. En cuanto a las propiedades fisico-quimicas, se caracterizo el compuesto comercial mediante resonancia nuclear magnetica de protones 1HRMN, 13CRMN, ultravioleta, cromatografia de gas masa y cromatografia de gas con detector de captura electronica. Se establecio su punto de fusion y la fraccion de particion octanol-agua. Se evaluo la estabilidad del compuesto comercial en el ambiente. Para ello, se mezclo tribromofenato sodico con una matriz de aserrin, verificandose una tasa de reduccion de un 52 % en 10 dias y de un 79,9 % en 150 dias. En los estudios de terreno efectuados en aserraderos ubicados en la intercomuna de Concepcion Penco, se detecto tribromofenol en el componente suelo y en aserrin en un rango de concentracion entre 0,006 y 1,651 mg kg-1.
El comportamiento electroquimico de compositos de polipirrol/polietilenglicol (Ppy-PEG) fue estudiado mediante voltametria ciclica, espectroscopia de impedancia electroquimica y microscopia electronica de barrido. De estos resultados se observo que tanto la electroactividad como la cinetica de transferencia de carga dependian de la concentracion de PEG utilizada durante el proceso de electropolimerizacion de pirrol. Mediante una adecuada funcion de transferencia fueron simulados los datos de impedancia obtenidos experimentalmente para este sistema polimerico y los parametros electricos fueron evaluados y discutidos en funcion de las condiciones de formacion de las peliculas obtenidas a diferentes concentraciones de PEG y de su morfologia.
An attempt was made to synthesize conformationally restricted nitrogen heterocycles by means of the Bischler-Napieralski reaction and Tsuda modification. Observed results prompted us to speculate on the nature of the effects which may be controlling such cyclization processes.
Los complejos sintetizados [RuCl2(2,6-dmpz)2(PPh3)2] y [RuCl2(CO)(N-het)(PPh3)2], (donde N-het son 2,6-dimetilpirazina (2,6-dmpz), Imidazol (Imz) y pirazina (pz)) PPh3 = trifenilfosfina, se sintetizaron a partir de RuCl2(PPh3)3 y un ligando N-heterociclico. Estos complejos se caracterizaron por tecnicas espectroscopicas. Para el complejo [RuCl2(2,6-dmpz)2(PPh3)2] el espectro Ir indica que los cloros se encuentran en posicion cis. El espectro electronico de los complejos presenta intensas bandas de transferencia de carga, asignadas a las transiciones de los orbitales dp llenos del rutenio a los orbitales pp * vacios de los anillos N-heterociclicos. Los estudios termicos de DSC y TGA para los complejos del tipo diclorocarbonil(N-heterociclico)bis(trifenilfosfina)rutenio(II), donde los N-heterociclicos son 2,6-dmpz, Imz y pz, indican que la estabilidad termica de los complejos depende de la nucleofilidad del ligando nitrogenado.
The exact knowledge of the value of the extinction coefficient of the ABTS derived radical is necessary for its quantitative use in the evaluation of the antioxidant capacity of pure compounds and/or complex mixtures. We have performed experiments in order to stablish its lower and upper limits of its value. The limits obtained, 1.0 X 10(4) M-1 cm(-1) less than or equal to epsilon(734) less than or equal to 1.6 x 10(4) M-1 cm(-1) are fully compatible with previously reported data. However, the use of these values leads to large stoichiometric coefficients for the reaction of these radicals with simple substrates, such as monophenols or tryptophan.
La reaccion entre el ion cis-[Co(NH3)4(H2O)2]3+ y amoniaco en presencia de un hidrato de carbono, conduce a la formacion del complejo tetranuclear de Cobalto (III): [Co4(NH3)12(OH)6]6+ (hexol), parcialmente resuelto en una proporcion que depende de la naturaleza del hidrato de carbono empleado
The soluble polysaccharides of few species of the family Rhodymenaceae (Rhodophyta) have been studied. According to the literature members of this family are agarophytes. Dried samples of tetrasporic, cystocarpic and gametophytic Rhodymenia howeana and tetrasporic R. corallina were analysed by FT-IR spectroscopy. Results indicate that these seaweeds are not agar producers. Aqueous extraction followed by chemical and FT-IR analysis showed that the extracts are very similar in composition. Carrageenotype structures in the polysaccharides were not found.
The antifungal activity of 10 (ten) depsidones and 5 (five) depsides was evaluated, as well as the antibacterial of these compounds and 3 (three) aditional depsides and the 1 (one) diarylether; all of them were isolated from lichens growing in Chile. Some of these secondary metabolites exhibited interesting results.
