Sensitive dependence of the hydrogen-bonded assemblies in cyanuric acid-4,4′-bipyridyl adducts on the solvent and the structure of the parent acid

Cyanuric acid (CA) forms a 2:1 hydrogen-bonded adduct with 4,4'-bipyridyl (BP) when co-crystallized from a methanol solution and a 1:1 adduct from an aqueous solution. The sheet structure of the 2:1 adduct involves cyclic hydrogen bonds between the amide units of adjacent CA molecules and N-H ... N bonds between CA and BP. The 1:1 adduct crystallized from water has a chain structure with single N-H ... O hydrogen bonds between the adjacent CA molecules. The structures of these hydrogen-bonded assemblies bear a close resemblance to the structures of CA crystallized from the corresponding solvents. N-methylcyanuric acid (MCA) forms a chain structure with single N-H ... O bonds between the adjacent MCA molecules. The 1:1 hydrogen-bonded adduct of MCA with BP, crystallized from methanol or water solution, retains the chain structure. The structural sensitivity of the hydrogen-bonded assemblies to the solvent of crystallization and the relation between the supramolecular assembly of the adduct and the parent structure of CA are noteworthy. (C) 2000 Elsevier Science B.V. All rights reserved.