Four interpenetrating hydrogen-bonded three-dimensional networks in divanillin.

The crystal structure of divainillin (systematic name: 6,6'-dihydroxy-5,5'-dimethoxy-[1,1'-biphenyl]-3,3'-dicarbaldehyde), C16H14O6, was determined from laboratory powder X-ray diffraction data using the software EXPO2013 (direct methods) and WinPSSP (direct-space approach). Divanillin molecules crystallize in the orthorhombic space group Pba2 (No. 32), with two molecules per unit cell (Z' = 1/2). Each divanillin molecule, with twofold symmetry, is linked through strong alcohol-aldehyde hydrogen bonds to four equivalent molecules, defining a three-dimensional hydrogen-bonding network, with rings made up of six divanillin units (a diamond-like arrangement). Each molecule is also connected through π-π interactions to a translation-equivalent molecule along c. Four consecutive molecules stacked along [001] belong to four different three-dimensional hydrogen-bonding networks defining a quadruple array of interpenetrating networks. This complex hydrogen-bonding array is proposed as an explanation for the aging process experienced by divanillin powders.