HYDROGEN-BONDING IN CRYSTAL ENGINEERING - 2-DIMENSIONAL LAYERS OF HYDROGEN L-MALATE ANIONS

Hydrogen L-malate anions can be utilized in the crystal engineering of ionic materials as a means of providing structural consistency and ri gidity by creating infinite anionic layers held together by directiona l O-H ... O hydrogen bonds. The syntheses and crystal structures of th ree new organic hydrogen L-malate salts, [AH][Hmal], are described (wh ere A = (4-methyl)benzylamine, (4-chloro)benzylamine and (3-chloro)ben zylamine). In each case, the anions create extended architectures (inf inite layers) via O-H ... O interactions. Each cation is then attached to one side of the anionic layer via three N-H ... O interactions. Th e layers are stacked in an AABBAABB... fashion with both anionic and c ationic sheets arranged in pairs throughout each crystal. The structur al influence of the cations, and the importance of the directionality and selectivity of hydrogen bonds in the construction of extended ''bu ilding blocks'', is discussed.