Supramolecular self assemblies in polymorphs/solvates of aminopyrimidine and amino-s-triazines derivatives

Polymorphs of 2-amino-4,6-dimethoxypyrimidine [ADMP (1)], 2,4-diamino-6-methyl-1,3,5-triazine [DAMT (2)], 2,4-diamino-6-phenyl-1,3,5-triazine [DAPT (3)] and a solvate of DAPT with DMF solvent, [DAPT·DMF (4)] were obtained either during a systematic screening using various solvents or by serendipity. These polymorphs and solvates were then characterized using single crystal X-ray diffraction technique and their structural and supramolecular aspects are analyzed. The supramolecular architecture of compounds (1–4) are predominantly hydrogen bonded via N–H⋯N base pairs. These base pairs are formed either between crystallographically independent molecules in the lattice or between symmetry related molecules. The molecular self assembly process involved in 2, 3 and 4, facilitates the formation of some base pair motifs with graph-set of R22(8) and a rare non-complementary base pair motif with graph-set R22(10). The other interesting supramolecular patterns and non-covalent interactions which lead to the formation of new forms are discussed in detail.