A bifunctional Zn-salen modified cavitand, reminiscent of the enzyme phospholipase C, shows high efficiency and synergic effect in the binding of the phospholipid DOPC.
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ABSTRACT Examples of reactivity of carbonyl and phosphoryl compounds controlled by calixarenes are illustrated in this review article. The molecular framework of calixarenes has been widely used as a versatile molecular platform for the... more
ABSTRACT Examples of reactivity of carbonyl and phosphoryl compounds controlled by calixarenes are illustrated in this review article. The molecular framework of calixarenes has been widely used as a versatile molecular platform for the dynamic arrangement of one or more structural units working as recognition and/or catalytic sites, in many cases with considerable levels of cooperation. The calixarene cavity itself has also been involved as a recognition unit for inclusion of the substrate or of part-structures of the substrate. Unique reactivity patterns of carbonyl or phosphoryl functional groups organised at the upper or lower rim of calixarenes will also be illustrated.
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PGMA polymer brushes are successfully grown on the inner wall of a microreactor to give a nanostructure. The oxirane groups of the brushes are used for the anchoring of a catalyst. The utility of the combination of catalyst-functionalized... more
PGMA polymer brushes are successfully grown on the inner wall of a microreactor to give a nanostructure. The oxirane groups of the brushes are used for the anchoring of a catalyst. The utility of the combination of catalyst-functionalized brushes and a microreactor is clearly demonstrated for the TBD-catalyzed Knoevenagel condensation reaction of benzaldehyde and malononitrile.
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Artificial phosphodiesterases that combine a guanidinium unit with a general base connected by a m-xylylene linker catalyze the transesterification of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). The bifunctional... more
Artificial phosphodiesterases that combine a guanidinium unit with a general base connected by a m-xylylene linker catalyze the transesterification of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). The bifunctional catalysts presented in this work show varying extents of cooperation between catalytic units and a rate enhancement of 4 × 10(4) in the most favorable case.
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ABSTRACT A self-assembled cylindrical capsule provides a nanoscale environment that affects the rotational barriers of tertiary amides. Measurements of the activation energies for the rotations and behaviors of the amides inside the... more
ABSTRACT A self-assembled cylindrical capsule provides a nanoscale environment that affects the rotational barriers of tertiary amides. Measurements of the activation energies for the rotations and behaviors of the amides inside the capsule were determined by using 1H NMR spectroscopic methods in deuterated mesitylene solution. For amides 3–8, rotation rates can decrease or increase in the capsule by up to an order of magnitude from those of the free amides in solution depending on the structure of the amides. The acceleration/deceleration of the rotation results from selective destabilization/stabilization of the ground state or the transition state. In the case of compound 10, the rotation generates two isomers that are equimolar in solution but inside the capsule only one of them is observed. Accordingly, the rotation rate is slowed by several orders of magnitude inside the capsule. In the case of amide 8, a competition experiment indicates that the acceleration of the rotation inside the capsule is due to destabilization of the ground state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
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The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an... more
The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single-layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X-Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large-area platelet films of single-layer graphene.