Browsing Facultad de Ciencias Exactas by Issue Date
Now showing items 1-20 of 309
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A complementary view to the bonding pattern in the N5 +cation an electron localization function and local temperature analysis
(Sociedad Chilena de Química, 2003)The electron localization function (ELF), a local measure of the Pauli repulsion effect, and the local Kohn-Sham temperature analysis, which is defined within the framework of a local thermodynamics description of density ... -
About the difference in the quadrupole splitting of water between cationic and anionic nematic lyotropic liquid crystals. H-2-NMR and molecular dynamics study
(SOCIEDAD CHILENA DE QUIMICA, 2004)Deuterium quadrupole splittings, of deuterated water, Deltav, in anionic discotic nematic lyomesophases are always much larger than in cationic mesophases. To explore the possible origins of this difference, Deltav and T-1 ... -
Quantitative representation of reactivity, selectivity and site activation concepts in organic chemistry
(Sociedad Chilena de Química, 2004)Reactivity, selectivity and site activation are classical concepts in chemistry which are amenable to quantitative representation, in terms of static global, local and non local density response functions. The use of ... -
On the reduction of 4-oxo-4h-benzopyran-3-carbaldehydes : global and local electrophilicity patterns
(Sociedad Chilena de Química, 2004)The theoretical global and local electrophilicity patterns of substituted and chelated 4-oxo-4H-benzopyran-3-carbaldehydes (formylchromones) have been evaluated using the electrophilicity index proposed by Parr et al [J. ... -
Spin-orbit effects metal-metal-multiple bonded m2x2 halide complexes
(Sociedad Chilena de Química, 2004)Dirac molecular spinor calculations on the Re2Cl82-, Re2Br82-, Os2Cl82- (both staggered and eclipsed isomers), Os2Br82- and Os2I82- cluster ions are reported. Here we report the calculations of the spin-orbit splitting ... -
On the use of the whole eigenvalue spectrum to obtain single molecule band structures and solid band gaps for molecular electronics studies
(Sociedad Chilena de Química, 2006)A Density Functional microscopic model of C60, consisting of seven molecular orbitals (3 occupied and 4 empty), was employed to get the best values for the half-width and the scanning distance of the mathematical function ... -
The limits of the extended hückel theory to calculate the total density of states of medium-sized molecules
(Sociedad Chilena de Química, 2006)Two medium-sized molecular systems X60 (X=C,N) were analyzed using Extended Hückel, Density Functional and ab initio Hartree-Fock methods. The aim of the work was to test the reliability of the EHT methodology to calculate ... -
Synthesis and conformational analysis of leptocarpin derivatives. Influence of modification of the oxirane ringon leptocarpin's cytotoxic activity.
(2014 Sociedad Chilena de Química, 2006)ABSTRACT The reaction in acidconditions of Leptocarpin 1, a compound with antitumor activity, formed two new isomeric products, 8b-angeloyl-1b,3b-dihydroxy-4,10-dimethyl,-D11(13) methylen-4Z,9Z-dieneheliangol-6,12-olide ... -
Algebraic cycles on Severi-Brauer Schemes of prime degree over a curve
(2007)Abstract. Let k be a perfect field and let p be a prime number different from the characteristic of k. Let C be a smooth, projective and geometrically integral k-curve and let X be a Severi-Brauer C-scheme of relative dimension ... -
On the metallicity of some carbon nanotubes
(Sociedad Chilena de Química, 2007)Some zigzag and all armchair single-walled carbon nanotubes are believed to behave as metals. However, recent experimental results suggest that only armchair single-walled carbon nanotubes show typically metallic behavior. ... -
Hydrophobically modified polyelectrolytes as potential drugs reservoirs of n-alkyl-nitroimidazoles
(Sociedad Chilena de Química, 2007)The solubilization of three commercial drugs (ornindazole, metronidazole and tinidazole) and model compounds (N-alkyl-2-methyl-4-nitroimidazoles) on aggregates formed by anionic polyelectrolytes, carrying alkyl side chains ... -
BRST Anomaly and Superspace Constraints of the Pure Spinor Heterotic String in a Curved Background
(2007)The pure spinor heterotic string in a generic super Yang-Mills and supergravity background is onsidered. We determine the one-loop BRST anomaly at the cohomological level. We prove that it can be absorbed by consistent ... -
Self-assembly of triblock copolymers in aqueous solution
(Sociedad Chilena de Química, 2008)The aggregation of PE4VP-b-PS-b-PE4VP block copolymers was studied in aqueous solution. Triblock copolymers P4VP-b-PS-b-P4VP were synthesized by sequential anionic polymerization of poly(styrene) and poly(4-vinylpirydine) ... -
Phenolics, depsides and triterpenes from the chilean lichen pseudocyphellaria nudata (zahlbr.) D.J. Galloway
(Sociedad Chilena de Química, 2008)The lichen Pseudocyphellaria nudata is a species endemic to southern South América. From the lichen tallus, methyl orsellinate, 2-methoxy-3,6-dimethyl-4-hydroxybenzaldehyde, methyl-evernate, tenuiorin, hopan-6ß,22-diol and ... -
Eugenol and its Synthetic Analogues Inhibit Cell Growth of Human Cancer Cells (Part I)
(Sociedad Brasilera de Química, 2008)Eugenol (4-allyl-2-methoxyphenol) (1) has been reported to possess antioxidant and anticancer properties. In an attempt to enhance intrinsic activity of this natural compound, some derivatives were synthesized. Eugenol ... -
A theoretical structure-affinity relationship study of some cannabinoid derivatives
(Sociedad Chilena de Química, 2008)A ZINDO/1 quantum-chemical structure-affinity relationship study with the KPG model is presented for the in vitro interaction of a group of classical, indole-derived and aminoalkylindole-derived cannabinoids with CB and ... -
Structural Parameters of the M87 Globular Clusters
(2009)We derive structural parameters for ∼ 2000 globular clusters in the giant Virgo elliptical M87 using extremely deep Hubble Space Telescope images in F606W (V) and F814W (I) taken with the ACS/WFC. The cluster scale sizes ... -
Facile synthesis of isoxazoles and pyrazoles from ß-diketohydrazones
(Sociedad Chilena de Química, 2009)New 3,5-dimethyl-4-[(E)-4-(R1-phenyl)diazenyl]isoxazoles and 3,5-dimethyl-1-(R2-phenyl)-4-[(E)-(R1-phenyl)diazenyl]-1H-pyrazoles may be obtained by reaction of 3-[2-(R1-phenyl)hydrazono)]pentane-2,4-dione with H2NOH-HCl ... -
An empirical way to correct some drawbacks of mulliken population analysis
(Sociedad Chilena de Química, 2009)The problem of negative electronic populations and of occupation numbers greater than 2 has plagued Mulliken Population Analysis since the very beginning. Through the analysis of three model molecular systems, several basis ... -
Enlaces de hidrógeno en ambientes fuertemente confinados
(Universidad Andrés Bello, 2009)RESUMEN: Esta tesis presenta un estudio teórico acerca de la naturaleza de los puentes de hidrógeno en regímenes de enlace normal y fuerte, y del efecto que en la reactividad química de los sistemas que los forman. Un ...
