<i>Cone</i> Calix[4]arenes with Orientable
Glycosylthioureido Groups at the Upper Rim: An In-Depth Analysis of
Their Symmetry Properties
LegnaniLaura
CompostellaFederica
SansoneFrancesco
TomaLucio
2015
The
two glycoclusters α- and β-d-mannosylthioureidocalix[4]arenes <b>1</b> and <b>2</b> in the <i>cone</i> geometry
have been submitted to a conformational investigation with the DFT
approach at the standard B3LYP/6-31G(d) level and using a water continuum
solvent model. After a reasoned choice of the level of calculation
and the evaluation of the properties of the monomeric components of <b>1</b> and <b>2</b>, the intrinsic conformational properties
of <i>cone</i> calix[4]arenes with orientable groups at
the upper rim were thoroughly analyzed. From the possible combinations
of the directions that the groups may assume, 10 different geometries
derive, all chiral. These geometries are interchangeable through two
different processes, named breathing equilibrium and arrow rotation,
that allow a dense network connection among them. When the modeling
of whole macrocycles <b>1</b> and <b>2</b> was performed,
a huge difference in their conformational behavior that heavily influences
the presentation mode of their saccharidic moieties was found.