The novel title macrocycles, based
on methylene-bridged 1,5-naphthalene
units, have been obtained by template effect in a thermodynamically
controlled synthesis. In detail, the prism[5]arene
1
or
the prism[6]arene
3
was selectively removed from the
equilibrium mixture by using the complementary ammonium-templating
agent. When only the solvent 1,2-DCE was used, the 1,4-confused derivative
2
was obtained. The prism[5]arene here described shows a deep
π-electron-rich aromatic cavity that exhibits a great affinity
for the quaternary ammonium guests, originating from favorable cation···π
and
+
NC–H···π interactions.
This recognition motif is the basis of the templated synthesis of
the prism[
n
]arenes here reported.
N-Benzyloxyethyl cyclic alpha-peptoids of various size were prepared and their conformational features were investigated by means of computational, spectroscopic, and X-ray crystallographic studies.
A novel catalytic feature of a hexameric resorcinarene capsule is highlighted. The self-assembled cage was exploited to promote the Friedel-Crafts benzylation of several arenes and heteroarenes with benzyl chloride under mild conditions. Calculations showed that there are catalytically relevant hydrogen-bonding interactions between the bridging water molecules of the capsule and benzyl chloride, which is fundamental for the activation of the C-Cl bond. The capsule controls the reaction outcome. Inside the inner cavity of the capsule, N-methylpyrrole is preferentially benzylated in the unusual β-position while mesitylene reacts faster than 1,3-dimethoxybenzene despite the greater π-nucleophilicity of the latter compound.
In this paper, we discuss the remarkable CO2 absorption properties of a new solvent-free porous organic solid, 1,2-dimethoxyp-tert-butylcalix[4]dihydroquinone. Exposure of 1 to H2 gas at 20 atm did not result in
detectable absorption of this gas. High selectivity for CO2
over H2 is a requirement if these materials are to be used
for CO2 separations from synthesis gas mixtures exiting, for
example, a water-gas shift reactor
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