Solvent-Induced Polymorphism of Three-Dimensional Hydrogen-Bonded Networks of Hexakis(4-carbamoylphenyl)benzene

The crystal structures for three types of three-dimensional (3-D) hydrogen-bonded networks of
hexakis(4-carbamoylphenyl)benzene (1), the network morphologies of which depend greatly on crystallization
conditions, have been determined. When this compound is crystallized from hot DMSO, the resulting crystals,
1·12DMSO (orthorhombic, Pca21), showed a 3-D hydrogen-bonded porous network (type A) via 1-D catemer
chains as a hydrogen-bonding motif of six primary amide groups. The type A network creates chambers
surrounded by six molecules of 1 and channels along the c axis to give the highest porosity among the
network polymorphs of 1 investigated here. Crystallization from a boiling mixture of n-PrOH and water
gave 1·6n-PrOH (monoclinic, P21/c), which exhibits another type of 3-D hydrogen-bonded porous network
(type B) via cyclic dimers as another hydrogen-bonding motif of six primary amide groups. The type B
network leads to triangle-like channels along the a axis having a cross section of ca. 9.2 × 9.7 × 9.7 Å
(including van der Waals radii). The crystal structure of 1·H2O (monoclinic, P21/c), which was produced
under hydrothermal conditions, showed a nonporous 3-D hydrogen-bonded network chain of amide groups
(type C) composed of a mixed hydrogen bonding motif of helical catemer chains/cyclic dimer/catemer.
Solvent-induced topological isomerism of these 3-D hydrogen-bonded networks of 1 arises from (i) the
guest inclusion ability based on a radially functionalized hexagonal structure of 1, (ii) the correlation between
the hydrogen bond donor ability of the syn and anti protons of the primary amide group in host 1 and the
hydrogen bond acceptor ability of the oxygen atoms of 1 and guest solvents, and (iii) the polarity of the
bulk crystallization solvents.