Triclinic polymorph of 4-[4-(4-formyl-phen-oxy)but-oxy]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).