Isomeric effect in structural studies of substituted nitro hydroxy-3-methoxy-benzaldehyde and nitro 2,3-dimethoxy-benzaldehyde derivatives

•The syntheses and structural studies of a 2 series of compounds derived from 3-Methoxysalicylaldehyde (o-vanillin), which were synthesized in three-step procedure.•3D molecular and crystal structure with supramolecular aggregates was confirmed by single crystal X-ray diffraction and discussed.•Hirshfeld Surface and energy framework Analyses were performed and discussed.•The crystal packing reveal that this type of compound is a good candidate for the develop of potential high-dose prolonged-release drugs for long-term control in the solid-state.•These derivatives can serve as starting materials in the synthesis of entacapone derivates.