2,2'-{1,1'-[Pentane-1,5-diyl-bis(oxy-nitrilo)]-diethyl-idyne}diphenol.

In the title compound, C(21)H(26)N(2)O(4), there is half a mol-ecule in the asymmetric unit with a crystallographic twofold rotation axis passing through the central C atom of the -CH=N-O-(CH(2))(5)-O-N=CH- bridge. The dihedral angle formed by the two benzene rings is 80.85 (2)°. Strong intra-molecular O-H⋯N and C-H⋯O hydrogen bonds help to establish the molecular conformation. There are also weak inter-molecular π-π stacking inter-actions between neighbouring benzene rings [centroid-centroid separation = 3.502 (3) Å].