Supramolecular Grid and Layer Architectures. Hydrogen Bonds and Halogen−Halogen Interactions Influenced by Bromo-, Chloro-, and Cyano-Substituted Anilic Acids

Supramolecular reactions were performed between 2,2‘-bipyrimidine (BPM) and 2,5-substituted cyano-
and haloanilic acids [cyananilic acid (CNA), chloranilic acid (ClA), and bromanilic acid, (BrA)] under identical reaction
conditions in methanol and a mixture of acetonitrile and methanol. The cyano and hydroxyl functional units of
CNA in supramolecular compound 1 are hydrogen-bonded through water molecules and form a two-dimensional
network with a grid motif. The grid cavities are occupied by BPM molecules, which are strongly linked by water
molecules that connect to the CNA network. The supramolecular architecture of 1 thus consists of a three-dimensional
hydrogen-bonded network. The 1:1:2 (H2O) compound 2 has intermolecular O−H···O and O−H···N hydrogen
bonds:  (i) ClA···H2O···BPM linked along the diagonal line of the bc-plane and (ii) BPM···H2O···BPM connected
along the b-axis. This structure includes strong Cl···Cl interactions at 3.34 Å, which generate a three-dimensional
packing arrangement as strengthened by acid···acid interaction. A new class of hydrogen-bonded 1:1:4 (H2O)
supramolecular compound 3 is formed from BPM, BrA, and water molecules, where structure formation is directed
by O−H···O and O−H···N hydrogen bonds, as well as weaker C−H···O and C−H···Br interactions between BPM
and BrA. Remarkable Br···Br interactions at 3.68 Å are observed that are similar to the Cl···Cl interactions in 2.
The three supramolecular compounds have been prepared with the specific aim of assessing a new donor−acceptor-type of hydrogen-bonded interactions to control the architecture of organic solids for the further invention of
supramolecular solid-state materials.