DI-HYDROXY MALONIC-ACID AS A BUILDING-BLOCK OF HYDROGEN-BONDED 3-DIMENSIONAL ARCHITECTURES

An examination of the crystal structures of di-hydroxy malonic acid 1 (P2(1)/na = 5.384(2), b = 6.268(2), c = 14.354(8) Angstrom, beta = 103 .57(3)degrees) and N-ethylbenzylammonium di-hydroxy hydrogenmalonate 2 (P2(1)2(1)2(1) a = 13.373(2), b = 15.342(4), c = 18.741(4) Angstrom) has highlighted the influence of directional O-H ... O interactions in the assembly of hydroxy-substituted dicarboxylic acids. The complemen tarity of carboxylic and hydroxy groups in 1 creates a very dense 3-D structure (D-c = 1.919 g cm(-3)) through four O-H ... O hydrogen bonds . In 2, the anions form infinite, spiraling chains created by head-to- tail O-H ... O hydrogen bonds. Neighbouring chains are crosslinked int o a complex 3-D anionic network with channels parallel to a and b. The cations are positioned within these channels and held in place via tw o N-H ... O interactions.