Supramolecular aggregation in three 4-aryl-6-(1H-indol-3-yl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles

Both 6-(1H-indol-3-yl)-3-methyl-4-(4-methylphenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile and 6-(1H-indol-3-yl)-3-methyl-4-(4-methoxyphenyl)-1-phenyl-1H-pyra- zolo[3,4-b]pyridine-5-carbonitrile crystallize from dimethylformamide solutions as stoichiometric 1:1 solvates, viz. C29H21N5 center dot C3H7NO, (I), and C29H21N5O center dot C3H7NO, (II), respectively; however, 6-(1H-indol-3-yl)-3-methyl-1-phenyl-4-(3,4,5trimethoxyphenyl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile, C31H25N5O3, (III), crystallizes in the unsolvated form. The heterocyclic components of (I) are linked by C-H...pi(arene) hydrogen bonds to form cyclic centrosymmetric dimers, from which the solvent molecules are pendent, linked by N-H...O hydrogen bonds. In (II), the heterocyclic components are linked by a combination of C-H...N and C-H...pi(arene) hydrogen bonds into chains containing two types of centrosymmetric ring, and the pendent solvent molecules are linked to these chains by N-H...O hydrogen bonds. Molecules of (III) are linked into simple C(12) chains by an N-H...O hydrogen bond, and these chains are weakly linked into pairs by an aromatic pi-pi stacking interaction.