Crystal structures and Hirshfeld surface analyses of 4,4'-{[1,3-phenyl-enebis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzaldehyde) and 4,4'-{[(1,4-phenyl-ene-bis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzalde-hyde).

The title compounds, CHO (I) and CHO (II), each crystallize with half a mol-ecule in the asymmetric unit. The whole mol-ecule of compound (I) is generated by twofold rotation symmetry, the twofold axis bis-ecting the central benzene ring. The whole mol-ecule of compound (II) is generated by inversion symmetry, the central benzene ring being located on an inversion center. In (I), the outer benzene rings are inclined to each other by 59.96 (10)° and by 36.74 (9)° to the central benzene ring. The corresponding dihedral angles in (II) are 0.0 and 89.87 (12)°. In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming ribbons propagating along the [10] direction. In the crystal of (II), mol-ecules are linked by C-H⋯O hydrogen bonds, forming a supra-molecular framework. The Hirshfeld surface analyses indicate that for both compounds the H⋯H contacts are the most significant, followed by O⋯H/H⋯O and C⋯H/H⋯C contacts.