Four N7-alkoxybenzyl-substituted 4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]-pyridine-5-spiro-1′-cyclohexane-2′,6′-diones: hydrogen-bonded supramolecular structures in zero, one, and two or three dimentions

3-tert-Butyl-7-(4-methoxybenzyl)-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C31H37N3O3, (I), 3-tert-butyl-7-(2,3-dimethoxybenzyl)-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C32H39N3O4, (II), 3-tert-butyl-4',4'-dimethyl-7-(3,4-methylenedioxybenzyl)-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione, C31H35N3O4, (III), and 3-tert-butyl-4',4'-dimethyl-1-phenyl-7-(3,4,5-trimethoxybenzyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione ethanol 0.67-solvate, C33H41N3O5 center dot-0.67C(2)H(6)O, (IV), all contain reduced pyridine rings having half-chair conformations. The molecules of (I) and (II) are linked into centrosymmetric dimers and simple chains, respectively, by C-H center dot center dot center dot O hydrogen bonds, augmented only in (I) by a C-H center dot center dot center dot pi hydrogen bond. The molecules of (III) are linked by a combination of C-H center dot center dot center dot O and C-H center dot center dot center dot pi hydrogen bonds into a chain of edge-fused centrosymmetric rings, further linked by weak hydrogen bonds into supramolecular arrays in two or three dimensions. The heterocyclic molecules in (IV) are linked by two independent C-H center dot center dot center dot O hydrogen bonds into sheets, from which the partial-occupancy ethanol molecules are pendent. The significance of this study lies in its finding of a very wide range of supramolecular aggregation modes dependent on rather modest changes in the peripheral substituents remote from the main hydrogen-bond acceptor sites.