Triclinic polymorph of 4-[4-(4-formyl­phen­oxy)but­oxy]benzaldehyde

The title compound, C₁₈H₁₈O₄, is a triclinic polymorph of the previously reported monoclinic polymorph [Han & Zhen (2005). Acta Cryst. E61, o4358–o4359]. In the crystal of the triclinic polymorph, molecules are linked by two pairs of C—H...O hydrogen bonds, forming a two-dimensional network parallel to (102), and enclosing loops with graph set motifs of R₂²(8) and R₂²(6).