Abstract:
In the first part of this investigation (Part I), cone conformers of calix[4]arenes with methylene and heteroatom
bridges from the Cambridge Structural Database (CSD) were investigated, in the second part (Part II) we
focused on structures of partial cone, 1,2-alternate and 1,3-alternate conformers with methylene- and heteroatom-
bridged calix[4]arenes represented in this Part II. This, third part (Part III) of the review is a sequel and it
is on conformations and geometry of calix[4]resorcinarenes scafolds, again using the data from the CSD. The
results were compared to data of calix[4]arene structures in our previous work. The effects of substitutions
and inter/intramolecular interactions present in the structure on the symmetry of the resorcinarene base frame
were evaluated with the help of previously introduced stereochemical parameters α, β, and δ. Utilization of
new, slightly modified scale of parameters α', β', δ' was tested, too. To sum up, these parameter are useful not
only for describing the geometry of calix[4]arenes, but for calix[4]resorcinarenes, too. The calix[
4]resorcinarenes seem to be more conformationally flexible and the «flat» arrangements are more favoured
there. Generally, the substitution is more complex and more irregular in the case of calix[
4]resorcinarenes, and it is relatively difficult to found some common patterns. However, as all these results
were obtained from solid state data, no conclusion concerning conformations and behavior of these molecules
in solution can be stated, similary as in the case of calix[4]arenes.
