Consistent supramolecular motif of <i>C</i> (7) O—H...O hydrogen-bonded chains and different local symmetries in three isoindole-4-carboxylic acid derivatives

The syntheses and structures of (3a<i>RS</i>,4<i>RS</i>,9a<i>SR</i>)-3-oxo-2-(2-phenyl-eth-yl)-2,3,3a,4,9,9a-hexa-hydro-1<i>H</i>-benzo[<i>f</i>]iso-indole-4-carb-oxy-lic acid, C₂₁H₂₁NO₃ (I), (3a<i>RS</i>,4<i>RS</i>,9a<i>SR</i>)-3-oxo-2-(propan-2-yl)-2,3,3a,4,9,9a-hexa-hydro-1<i>H</i>-benzo[<i>f</i>]iso-indole-4-carb-oxy-lic acid, C₁₆H₁₉NO₃ (II) and (4<i>RS</i>)-3-oxo-2-phenyl-2,3,4,9-tetra-hydro-1<i>H</i>-benzo[<i>f</i>]iso-indole-4-carb-oxy-lic acid, C₁₉H₁₅NO₃ (III), are described. Compound (I) crystallizes with two mol-ecules in the asymmetric unit. In the extended structures of (I), (II) and (III) the mol-ecules are linked by O_c-H⋯O_i (c = carb-oxy-lic acid, i = indole) hydrogen bonds, forming a common <i>C</i>(7) zigzag chain motif propagating along the [010] direction, despite the different local symmetries. These chains are connected by weak C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network in each case. A Hirshfeld surface analysis was undertaken to investigate and qu-antify the inter-molecular inter-actions, which are dominated by H⋯H, C⋯H/H⋯C and O⋯H/H⋯O contacts in each case.