RESUMEN

The asymmetric unit of the title compound, C27H20O3, contains two independent mol-ecules (A and B). The anthracene ring system is connected to the 2,7-di-meth-oxy-naphthalene core in a twisted manner, with dihedral angles of 86.38 (5) and 79.36 (8)°, respectively, for conformers A and B. In the crystal, face-to-face type dimeric mol-ecular aggregates of each conformer are observed. The dimer of conformer A is formed by two pairs of C-H⋯π inter-actions, and that of conformer B by a pair of (sp2)C-H⋯O hydrogen bonds. The dimers of conformer A are linked to each other via a π-π stacking inter-action between the anthracene rings to form a chain along the b axis and the chains are aligned along the c axis, forming a sheet structure. The dimers of conformer B are connected to each other via a couple of C-H⋯π inter-actions to form a chain along the b axis. The chains are aligned along the c axis through (sp2)C-H⋯O=C hydrogen bonds, forming a sheet parallel to the bc plane. The sheets of conformers A and B are alternately stacked along the a axis via two kinds of inter-molecular (sp2)C-H⋯O=C hydrogen bonds.

RESUMEN

Two (ONO pincer)ruthenium-complex-bound norvalines, Boc-[Ru(pydc)(terpy)]Nva-OMe (1; Boc=tert-butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc-[Ru(pydc)(tBu-terpy)]Nva-OMe (5), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single-crystal X-ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high-temperature conditions enabled us to perform selective transformations of the N-Boc and C-OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru-bound norvaline, n-C11 H23 CO-l-[Ru(pydc)(terpy)]Nva-NH-n-C11 H23 (l-4) was found to have excellent self-assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru-bound norvaline l-1 exhibited a higher catalytic activity for the oxidation of alcohols by H2 O2 than parent complex [Ru(pydc)(terpy)] (11 a).

Asunto(s)

RESUMEN

The NCN-pincer Pd-complex-bound norvalines Boc-D/L-[PdCl(dpb)]Nva-OMe (1) were synthesized in multigram quantities. The molecular structure and absolute configuration of 1 were unequivocally determined by single-crystal X-ray structure analysis. The robustness of 1 under acidic/basic conditions provides a wide range of N-/C-terminus convertibility based on the related synthetic transformations. Installation of a variety of functional groups into the N-/C-terminus of 1 was readily carried out through N-Boc- or C-methyl ester deprotection and subsequent condensations with carboxylic acids, R(1)COOH, or amines, R(2)NH2 , to give the corresponding N-/C-functionalized norvalines R(1)-D/L-[PdCl(dpb)]Nva-R(2) 2-9. The dipeptide bearing two Pd units 10 was successfully synthesized through the condensation of C-free 1 with N-free 1. The robustness of these Pd-bound norvalines was adequately demonstrated by the preservation of the optical purity and Pd unit during the synthetic transformations. The lipophilic Pd-bound norvalines L-2, Boc-L-[PdCl(dpb)]Nva-NH-n-C11H23, and L-4, n-C4H9CO-L-[PdCl(dpb)]Nva-NH-n-C11H23, self-assembled in aromatic solvents to afford supramolecular gels. The assembled structures in a thermodynamically stable single crystal of L-2 and kinetically stable supramolecular aggregates of L-2 were precisely elucidated by cryo-TEM, WAX, SAXS, UV/Vis, IR analyses, and single-crystal X-ray crystallography. An antiparallel ß-sheet-type aggregate consisting of an infinite one-dimensional hydrogen-bonding network of amide groups and π-stacking of PdCl(dpb) moieties was observed in the supramolecular gel fiber of L-2, even though discrete dimers are assembled through hydrogen bonding in the thermodynamically stable single crystal of L-2. The disparate DSC profiles of the single crystal and xerogel of L-2 indicate different thermodynamics of the molecular assembly process.

Asunto(s)

RESUMEN

Pd- and Pt-bound bis-metalated peptides were synthesised by the condensation of Pd- or Pt-aldimine-complex-bound glutamic acids to afford the four possible metal isomers of bis-Pd and bis-Pt-homometalated dipeptides and PdPt- and PtPd-heterometalated dipeptides without metal disproportionation. Ultrasound-induced self-assembly of these bis-metalated peptides proceeded effectively to afford supramolecular gels that displayed well-ordered metal arrays. The formation of parallel ß-sheet type aggregates through interpeptide amide-amide hydrogen bonding was confirmed by IR, scanning electron microscopy (SEM), and synchrotron X-ray diffraction analyses (WAXS and SAXS). The mechanism of the ultrasound-induced self-assembly of the metalated dipeptides was elucidated via kinetic and association experiments by (1)H NMR, in which ultrasound-triggered dissociation of intramolecular hydrogen bonds between the chloride ligands of the Pd- and Pt-complexes and amides initially occurred. This was followed by the formation of intermolecular amide-amide hydrogen bonds, which afforded the corresponding oligomeric peptide self-assembly as the nucleus for supramolecular aggregation. The observed first-order relationship of the gelation rate versus the sonication frequency suggested that the microcavitation generated under sonication conditions acted as a crucial trigger and provided a reaction field for efficient self-assembly.

Asunto(s)

RESUMEN

A new type of Pt-complex-bound amino acid was synthesized by condensation of a cyclometalated Pt complex with the side-chain residue of N- and C-alkylated glutamic acid. Self-assembly of the Pt-bound lipophilic amino acid afforded a supramolecular gel in organic solvents, which comprised fibrous lamellar aggregates that supported a highly oriented Pt array.

Asunto(s)

RESUMEN

The synthesis, structure, and dynamic behavior of bistable C- and N-bound isomers of transition-metal cyanocarbanions are described. A series of C-bound cyclopentadienyl (Cp) ruthenium phosphane complexes, [Ru{CH(CN)SO2Ph}(Cp)L1L2] (3), and their N-bound isomers, [Ru+(Cp)(NCCH(-)SO2Ph)L1L2] (4), were prepared by treating [RuCl(Cp)(PR3)2] with the sodium salt of phenylsulfonylacetonitrile and performing ligand-exchange reactions with the resulting compounds. Structural characterization by X-ray diffraction indicates that the cyanocarbanion moiety of 3 has an alpha-metalated structure, whereas that of 4 has a zwitterionic, end-on structure. Heating these complexes in aprotic solvents gives rise to irreversible linkage isomerization between C- and N-bound isomers, in which the relative thermal stabilities vary greatly depending on the steric and electronic nature of the ligands. Mechanistic studies of N-to-C isomerization revealed that the reaction proceeds irreversibly in a unimolecular manner without the formation of coordinatively unsaturated species. A metal-sliding process, which occurs over the -C-C triple chemical bond N pi-conjugated surface of the cyanocarbanion moiety, was suggested by results from kinetic studies and density functional theory (DFT) calculations. C-to-N isomerizations proceed by the above-mentioned intramolecular process, with a temperature-dependent contribution from the formation and cleavage of mu2-C,N coordination dimers [{Ru{CH(CN)SO2Ph}(Cp)(PPh3)}2] (15 and 16).

Asunto(s)

RESUMEN

Los autores estudiaron al azar por medio de manometría anorectal y serie gastrointestinal a 28 pacientes, de Santa María Ixhuatán, Depto. de San Rosa, Guatemala (área endémica de Chagas) dividido en 3 grupos: Grupo A: 5 pacientes seropositivos para Chagas más estreñimiento. Grupo B: 10 pacientes seropositivos para Chagas sin estreñimiento y, Grupo C: 13 pacientes seronegativos. Los resultados de la manometría anorectal de los 3 grupos fueron estadísticamente analizados por método descriptivo, con la prueba Kruskal-Wallis y gráficas de cajas de Tukey, verificándose que no había diferencia significativa entre los hallazgos de los 3 grupos,así como también no se verificó la presencia de megaesófago, ni megacolon en los pacientes estudiados, como hallazgo curioso en 4 de 5 pacientes el grupo A se comprobó radiológicamente: Ptosis gástrica que aparentemente no tiene relación con Enfermedad de Chagas

Asunto(s)

Asunto(s)

RESUMEN

Estudio ralizado en 82 pacientes originariosy residentes de la población de Santa María Ixhuatán, Santa Rosa, Guatemala, quienes presentaban alguna alteración electrocardiográfica y/o serología positiva y que fueron detectado en el primer estudio. Fueron evaluados por medio de Ecocardiografía Bidimensional con Modo M. Holter de 24 horas y Rx de Tórax. El propósito del presente estudio es el de establecer el grado de afección cardiáca detectado por métodos no invasivos y establecer la prevalencia de la misma en el área endémica objeto de estudio. Se encontró 31/100 con cardiomegalia grado I, el 7.0/100 grado II, el 2.5/100 grado III según Rx. Con el ecocardiograma, únicamente el 9.8 por ciento (4/41seropositivo) presentan micardiopatía dilatada sugestiva enfermedad de Chagas, encontrándose disminución leve de la fracción de eyección en 2 casos hiposcineciade la pared posterior en l caso, discenecia del tercio superior del septum en 1 caso. El daño a válvula mitral es del 20/100. Se excluyeron algunas otras patologías diagnosticadas como: cardiopatías arterioesclerótica,hipertensiva, mixta reumática y secundaria a enfermedad pulmonar obstructiva crónica. Con Holter, conlo que corresponde a las alteraciones del ritmo: además de extrasístole ventriculares en un 39/100 de los casos seropositivos, tabulandose según la clasificacióde Lown: Cardiopatía grado 1:10.0/100 grado II:5.0/100 grado III: 0.0/100 grado IV:5.0/100. Se concluye en esta muestra que la cardiopatía Chagásica Crónica detectada por Ecocardiograma y Holter es de 22.0/100 (18/32), el 77/100 es debido a tejido de conducción y el 22/100 afecta al tejido muscular. La prueba que obtiene mayores datos para cuantificar el daño al miocardio es el Ecocardiograma, el cual elimina otro tipo de patologías que pueda provocar alteraciones electrocardiográ, el cual elimina otro tipo de patologías que pueda provocar alteraciones electrocardiográficas o cardiomegalias detectadas por radiografía de tórax. La enfermedad de Chagas es importante en nuestro país y consideramos la necesidad de incrementar el análisis desde diferentes puntos de vista para tener una idea de este problema

Asunto(s)

RESUMEN

It is generally that the gastrointestinal manifestation from Chagas disease in Central America is very rare. But this thesis is not fully evidenced with sofisticated inveestigation. In order to determine this thesis,an investigation focused on the gastro-intestinal tract by electro-manometry and X-ray was performed.

Asunto(s)

Asunto(s)