6,6′-Dihydr­oxy-2,2′-[(butane-1,4-diyldi­oxy)bis­(nitrilo­methyl­idyne)]diphenol

The mol­ecule of the centrosymmetric title compound, C18H20N2O6, assumes an E configuration with respect to the azomethine C=N bond. The imino group is coplanar with the aromatic ring. Intra­molecular O—H⋯O and O—H⋯N bonds are found between the hydroxyl groups and adjacent O (or N) atoms. In the crystal structure, inter­molecular O—H⋯O bonds link each mol­ecule to two others, forming a layered network.