E and Z Secondary Amides in Supramolecular Nanotubes and Nanospheres - Molecular Self-Assembly: Advances and Applications - page 52

secondaryamides.Wethoughtthatthisconstitutedadeficiency
whichhadtoberemedied.Flatormildlycurved C symmetric

3

molecules with three -amides appeared to be the ideal candidates

because they would open the gate to the wealthiest family of platonic
solidslikeCTVs.Thenewsubunitshadtobesmallenough,sufficiently
lipophilic and shaped like triangles for a better tiling. The triamide
(

Z

),basedonthemesytilenescafold,cameoutalmostnaturally
(Fig.2.17)[86].Crystaldataandcalculationssuggestedthat(

4

4 )

easily adopts preferentially a dissymmetrical shape. However, the

symmetricconformerislessstablebyonly0.43kcal/mol.Thelatter
symmetric conformer only is prone to self-assemble as spheres.
Its dimeric capsule is much more stable than the “pacman”-like
object issued from supramolecular dimerization of the asymmetric
conformer.Thediferenceof6.15kcal/molbetweenthetwodimers
is proportional to the number of hydrogen bonds involved: 6 in the
capsule and only 4 in its competitor.

C

3

Figure 2.16. Schematic representation of spherical capsules built from

triangle, square and pentagone molecules and based on the
geometry of platonic solids.