Synthesis and Spectral Characterization of Lanthanide Complexes with Sulfamethoxazole and Their Antibacterial Activity

A series of nonelectrolytic lanthanide(III) complexes, [ ML 2 Cl 3 ] · 2 H 2 O, where M is lanthanum(III), praseodymium(III), neodymium(III), samarium(III), gadolinium(III), terbium(III), dysprosium(III), and yttrium(III), containing sulfamethoxazole ligand (L) are prepared. The structure and bonding of the ligand are studied by elemental analysis, magnetic susceptibility measurements, IR, 1 H NMR, TG / DTA , X-ray diffraction studies, and electronic spectra of the complexes. The stereochemistry around the metal ions is a monocapped trigonal prism in which four of the coordination sites are occupied by two each from two chelating ligands, sulfonyl oxygen, and nitrogen of the amide group and the remaining three positions are occupied by three chlorines. The ligand and the new complexes were tested in vitro to evaluate their activity against the bacteria Escherichia coli and Staphylococcus aureus.

Acid base characteristics of binary oxides of Zr with Ce and La

The surface acidity and basicity of binary oxides of Zr with Ce and La are determined using a series of Hammet indicators and Ho,,max values are reported. The generation of new acid sites habe been ascribed to the charge imbalance of M1-O-M2 bonds, where M1 and M2 are metal atoms. Both Bronsted and Lewis acid sites contribute to the acidity of the oxides

Fabrication of Potentiometric Sensors for the Determination of Lanthanide Ions

In many fields such as earth science biology, environment and electronics, the knowledge about elemental distributions and chemical speciation is important. The determination of metal levels especially the toxic ones both in the environment and in biological materials are increasingly demanded by the society.Ion selective sensors have become one of the most effective ad powerful means for analytical scientists for the trace level monitoring of metal ions. The wide range of applications ,low material requirements and simplicity of analytical procedure have not only brought ion-selective electrodes in to the lime light of analytical chemistry,but have promoted their use as tools for physiologists,medical researchers,biologists,geologists,environmental protection specialists etc.Potentiometric ion-selective sensors have been developed for the determination of lanthanide ions such as La3+,Nd3+,Pr3+,Sm3+, and Gd3+.The sensors fabricated include both PVC membrane sensor and chemically modified carbon paste sensor. A set of 10 sensors have been developed. The response parameters of all the sensors have been studied and the sensors were applied as an indicator electrode in the potentiometric titration and for the determination of metal ions in real samples.

Theoretical approach to the magnetostructural correlations in spin-Peierls compound CuGeO3

A theoretical density-functional study has been carried out to analyze the exchange coupling in the chains of CuGeO3 using discrete models. The results show a good agreement with the experimental exchange coupling constant (J) together with a strong dependence of J with the Cu-O-Cu angle. The calculation of the J values for a distorted model indicates a larger degree of dimerization than those reported previously.

An inhibitory compound produced by Pseudomonas with effectiveness on Vibrio harveyi

Persistence of the antivibrio property of the potential antagonistic probiotics, Pseudomonas MCCB 102 and 103, at di¡erent temperatures, pH and in organic solvents was studied. The antivibrio compound was extracted, puri¢ed and characterized using thin-layer chromatography, high-pressure liquid chromatography, liquid chromatography-mass spectroscopy, UV^ Vis and nuclear magnetic resonance spectroscopy and identi¢ed as N-methyl-1-hydroxyphenazine, a phenazine antibiotic. The toxicity of the compound was tested in Penaeus monodon haemocyte culture and the IC50 valuewas found to be1.4 0.31mg L 1. The compound was found to be bacteriostatic at 0.5mg L 1. Its stability to varying temperature, pH, organic solvents, prolonged shelf-life and vibriostatic nature point to its suitability for prophylatic aquaculture application.

Derived control by compound and single stimuli in a matching-to-sample task in children

Resumen tomado de la publicaci??n

New mono- and dinuclear ruthenium complexes containing the 3,5-bis(2-pyridyl)pyrazole ligand. Synthesis, characterization and applications

Se han sintetizado dos nuevos complejos mononucleares de Ru, con formula [RuCl2(Hbpp)(dmso)2], a partir de la reacción entre [RuCl2(dmso)4] y Hbpp (3,5-bis(2-piridil)pirazola). El hecho que sólo tres de los seis posibles estereoisómeros se obtengan a partir de esta reacción, se ha racionalizado en base a factores estructurales y electrónicos. Estos complejos se han caracterizado de forma estructural, espectroscópica y electroquímica. En acetonitrilo en medio básico, el isómero trans,cis-[RuCl2(Hbpp)(dmso)2] da lugar a procesos de isomerización de enlace de un ligando dmso cuando el Ru(II) se oxida a Ru(III). Las constantes termodinámicas y cinéticas para el proceso se han determinado por voltametria cíclica. La irradiación de trans,cis-[RuCl2(Hbpp)(dmso)2] y cis(out),cis-[RuCl2(Hbpp)(dmso)2] con luz UV o solar da lugar a reacciones de fotosustitución de un ligando dmso por una molécula de acetonitrilo para dar un nuevo compuesto el cual ha sido caracterizado en solución por técnicas espectroscópicas y electroquímicas. Ambos complejos resultan catalizadores útiles en la transferencia de hidrógeno de isopropanol a acetofenona, obteniéndose 1-feniletanol como único producto y un 42.1% de conversión (36.1 ciclos metálicos) a 80ºC con el isómero trans,cis-[RuCl2(Hbpp)(dmso)2], que resulta significativamente más eficaz que el complejo cis(out),cis-[RuCl2(Hbpp)(dmso)2]. La reacción de cis(out),cis-[RuCl2(Hbpp)(dmso)2] con trpy (2,2':6',2"-terpiridina) da lugar a los dos isómeros geométricos del complejo [Ru(Hbpp)(trpy)(Cl)]+, el in y el out. Estos complejos se han aislado y caracterizado por técnicas estructurales, espectroscópicas y electroquímicas. Estos cloro complejos han sido utilizados como precursores para la síntesis de los complejos análogos con ligandos aqua (in,out-[Ru(Hbpp)(trpy)(H2O)]2+) y piridina (in,out-[Ru(Hbpp)(trpy)(py)]2+), los cuales también han sido aislados y caracterizados. Las propiedades ácido-base de los aqua complejos, y del complejo out-py se han estudiado detalladamente por voltametria cíclica y mediante valoraciones espectrofotométricas ácido-base. El tratamiento matemático de los datos así obtenidos nos ha permitido determinar los valores de pKa para los distintos equilibrios de protonación de los complejos en los estados de oxidación II y III. El complejo out-aqua ha demostrado ser un buen catalizador para la oxidación electroquímica del alcohol benzílico, presumiblemente a benzaldehido. La constante de velocidad de segundo orden para el proceso ha sido determinada como 17.1 M-1 s-1, por simulación matemática. El dímero con un puente cloro, [Ru2Cl(bpp)(trpy)2]2+ ha sido preparado por dos rutas sintéticas diferentes. El dímero análogo con un puente acetato se ha obtenido por reacción del cloro dímero con un exceso de acetato sódico. El dímero con dos ligandos aqua [Ru2(bpp)(trpy)2(OH2)2]3+ puede obtenerse por hidrólisis ácida del complejo con un acetato puente o por hidrólisis básica del complejo con un puente cloro. Estos complejos han sido caracterizados por técnicas estructurales, espectroscópicas y electroquímicas. Las soluciones del dímero con dos ligandos aqua en medio ácido resultan inestables a la coordinación de aniones de la solución con el tiempo. Las propiedades ácido-base del dímero con dos aguas coordinadas han sido estudiadas por voltametria cíclica y mediante experimentos de electrólisis a potencial controlado. El pKa para la desprotonación de uno de los ligandos aqua ha sido determinado mediante una valoración espectrofotométrica ácido-base como 6.7. Este valor tan bajo de pKa se atribuye a la formación de la entidad {Ru2O2H3}, favorable termodinámicamente. Los espectros UV-vis para los distintos estados de oxidación del aqua dímero, de RuIIRuII a RuIIIRuIV, han sido obtenidos por oxidación química y electroquímica del complejo. Se han llevado a cabo estudios cinéticos de la oxidación, paso a paso, de RuII,II a RuIV,IV , y se han determinado las constantes de oxidación de segundo orden para los distintos procesos de oxidación. La capacidad del aqua dímero en la oxidación del agua a oxígeno molecular ha sido investigada en solución homogénea utilizando CeIV como oxidante. La evolución de oxígeno se ha demostrado por cromatografia de gases. Se ha obtenido una eficiencia del 73% y 18.6 ciclos catalíticos, cuando 1.83 x 10-6 moles de dímero se han mezclado con un exceso de 100 equivalentes de cerio. El dímero con dos aguas cataliza también la oxidación del agua de forma heterogénea, con el complejo adsorbido sobre una membrana de nafion, aunque la eficiencia es menor. Se ha propuesto un mecanismo intramolecular para la reacción de oxidación del agua. Consiste en la oxidación a 4 electrones del dímero, de RuII,II a RuIV,IV, el cual reacciona con el agua para formar oxígeno y revierte nuevamente al estado de oxidación II,II. Este modelo es consistente con estudios catalíticos de la evolución de oxígeno en función de las concentraciones de cerio y catalizador, llevados a cabo en solución ácida homogénea, que demuestran que la oxidación a 4 electrones del agua se encuentra catalizada por una sola molécula de complejo bajo concentraciones elevadas de cerio. La constante de pseudo-primer-orden para la evolución de oxígeno tiene un valor de 1.4 x 10-2 s-1, que es uno de los valores de constante más elevados obtenidos hasta la fecha. Desafortunadamente, el aqua dímero se desactiva durante el proceso de catálisis dando lugar a una especie naranja, la cual estamos actualmente tratando de caracterizar.

Shear controlled crystal size definition in a low molar mass compound using a polymeric solvent

We show that close to monodisperse crystalline fibrils of dibenzylidene sorbitol can be obtained by preparation in a polymeric solvent subjected to extended shear flow.

Investigation of the effects of the novel anticonvulsant compound carisbamate(RWJ-333369) on rat piriform cortical neurones in vitro

Background and purpose: Carisbamate is being developed for adjuvant treatment of partial onset epilepsy. Carisbamate produces anticonvulsant effects in primary generalized, complex partial and absence-type seizure models, and exhibits neuroprotective and antiepileptogenic properties in rodent epilepsy models. Phase IIb clinical trials of carisbamate demonstrated efficacy against partial onset seizures; however, its mechanisms of action remain unknown. Here, we report the effects of carisbamate on membrane properties, evoked and spontaneous synaptic transmission and induced epileptiform discharges in layer II-III neurones in piriform cortical brain slices. Experimental approach: Effects of carisbamate were investigated in rat piriform cortical neurones by using intracellular electrophysiological recordings. Key results: Carisbamate (50–400 mmol·L-1) reversibly decreased amplitude, duration and rise-time of evoked action potentials and inhibited repetitive firing, consistent with use-dependent Na+ channel block; 150–400 mmol·L-1 carisbamate reduced neuronal input resistance, without altering membrane potential. After microelectrode intracellular Cl- loading, carisbamate depolarized cells, an effect reversed by picrotoxin. Carisbamate (100–400 mmol·L-1) also selectively depressed lateral olfactory tract-afferent evoked excitatory synaptic transmission (opposed by picrotoxin), consistent with activation of a presynaptic Cl conductance. Lidocaine (40–320 mmol·L-1) mimicked carisbamate, implying similar modes of action. Carisbamate (300–600 mmol·L-1) had no effect on spontaneous GABAA miniature inhibitory postsynaptic currents and at lower concentrations (50–200 mmol·L-1) inhibited Mg2+-free or 4-aminopyridine-induced seizure-like discharges. Conclusions and implications: Carisbamate blocked evoked action potentials use-dependently, consistent with a primary action on Na+ channels and increased Cl- conductances presynaptically and, under certain conditions, postsynaptically to selectively depress excitatory neurotransmission in piriform cortical layer Ia-afferent terminals.

Vibrational spectroscopy of a compound with a CS7 ring

The product of the Asinger reaction between elemental sulfur, n-butylamine and acetophenone is 8-(n-butylaminophenylmethyliden)-1,2,3,4,5,6,7-heptathiocane which contains a CS7 ring. A combination of infrared, Raman and inelastic neutron scattering spectroscopies with periodic density functional theory calculations is used to provide a complete assignment of the vibrational spectra of this unusual species. The similarity between the Raman spectra of the compound and that of elemental sulfur is particularly striking. Copyright (C) 2009 John Wiley & Sons, Ltd.

Synthesis and crystal structure of the thiophene-3-acetonitrile complex fac-[Mo(CO)(3){NCCH2(C4H3S-3)}(3)]

Reaction of fac-[ Mo( CO)(3)( NCMe)(3)] with three equivalents of NCCH2(C4H3S- 3) in acetonitrile gives the tris(thiophene- 3- acetonitrile) complex, fac-[Mo(CO)(3){NCCH2(C4H3S-3)}(3)] (1) in 7% yield. Complex 1 crystallizes out in the orthorhombic space group Pnma with a = 12.714( 17), b = 16.41( 2), c = 11.304(16) Angstrom, Z = 4. The structure has crystallographic m symmetry and the metal is in an almost perfect octahedral environment, with a facial arrangement of carbonyl and thiophene- 3- acetonitrile groups. The thiophene rings are disordered.

A hexadecanuclear copper(I)-copper(II) mixed-valence compound: structure, magnetic properties, intervalence charge transfer, EPR, and NMR

Hexadecanuclear copper mixed-valence complex 2 containing 10 Cu-II, centers and 6 Cu-I centers was isolated with N,O donor ligands. From the X-ray crystal structure, 2 was found to contain a centrosymmetric dimeric cation - each monomeric unit composed of eight copper centers. It displays a very broad and weak intervalence charge-transfer band around 1100 nm at room temperature in the solid state. Variable-temperature magnetic susceptibility measurements indicate an S = 1/2 ground state for half of 2, explicitly, each Cu-8 moiety has a g value around 2.26. Complex 2 was examined by NMR spectroscopy at room temperature in solution and by EPR at low temperature; the data indicates that the valence is delocalized in 2 at room temperature but localized at low temperature. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)