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Templating Effect (templating + effect)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Templating Effect of Lipid Membranes on Alzheimer's Amyloid Beta Peptide

CHEMPHYSCHEM, Issue 2 2005
Canay Ege Dr.
Electrostatic influence on peptide association: The first X-ray reflectivity and grazing-incidence X-ray diffraction study on amyloid beta peptide and lipid monolayers provides insight into the differences in the interaction of the peptide with cationic and anionic monolayers (see picture). A unique templating effect is observed in the latter case. [source]

High-Zirconium-Content Nano-Sized Bimodal Mesoporous Silicas

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006
David Ortiz de Zárate
Abstract Silica-based nanoparticulated bimodal mesoporous materials with high Zr content (43 , Si/Zr , 4) have been synthesized by a one-pot surfactant-assisted procedure from a hydroalcoholic medium using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure-directing agent, and starting from molecular atrane complexes of Zr and Si as hydrolytic inorganic precursors. This preparative technique allows optimization of the dispersion of the Zr guest species in the silica walls. The bimodal mesoporous nature of the final high surface area nano-sized materials is confirmed by XRD, TEM, and N2 adsorption,desorption isotherms. The small intraparticle mesopore system (with pore sizes around 2,3 nm) is due to the supramolecular templating effect of the surfactant, while the large mesopores (around 12,24 nm) have their origin in the packing voids generated by aggregation of the primary nanometric mesoporous particles. The basicity of the reaction medium seems to be a key parameter in the definition of this last pore system. The effects induced by the progressive incorporation of Zr atoms on the mesostructure have been examined, and the local environment of the Zr sites in the framework has been investigated by UV/Vis spectroscopy. Observations based on the consequences of post-treatments of the as-synthesized materials with HCl/ethanol mixtures corroborate that the atrane method leads to Zr-rich materials showing enhanced site accessibility and high chemical homogeneity throughout the pore walls. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

The Synthesis and Characterization of all Diastereomers of a Linear Symmetrically Fused Tris-Tröger's Base Analogue: New Chiral Cleft Compounds

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2006
Josep Artacho
Abstract The synthesis and characterization of all diastereomers of a linear symmetrically fused tris-Tröger's base analogue are described. The diastereomers are unambiguously assigned as syn,anti1,a, anti,anti1,b, and syn,syn1,c isomers, by using X-ray diffraction analysis and NMR spectroscopy. For the first time, the anti,anti and the syn,syn diastereomers of a linear symmetrically fused tris-Tröger's base analogue have been synthesized. Molecules 1,a and 1,c are new cleft compounds and analysis of compound 1,a in the solid state shows inclusion of one molecule of CH2Cl2 in the larger aromatic cleft, whereas in isomer 1,c disordered solvent molecules are trapped in the extended aromatic cleft. Furthermore, in the solid state, isomer 1,c forms infinite open channels along one of the crystallographic axes and perpendicular to this axis there are infinitely extending "wedged-ravines". Importantly, each of the diastereomers 1,a,c is resistant to inversion at the stereogenic nitrogen atoms under strongly and weakly acidic conditions in the range from room temperature (RT) to 95,°C. This observed configurational stability at the stereogenic nitrogens of 1,a,c is unique for analogues of Tröger's base in general to date. Finally, the ratio of cleft compounds 1,a and 1,c significantly increased relative to cavity compound 1,b when ammonium chloride was used as an additive in the Tröger's base condensation to 1,a,c suggesting a templating effect of the ammonium ion. [source]