Homochiral zinc phosphonates with layered and open framework structures using polycarboxylate as second linkers

Reactions of zinc sulfate and (R)- or (S)-(1-phenylethylamino) methylphosphonic acid (pempH(2)) in the presence of 1,4-benzenedicarboxylic acid (H(2)bdc) result in homochiral enantiomers (R)- and (S)-[Zn-4(pempH)(4)(bdc)(2)]center dot 2H(2)O (1). When H(2)bdc is replaced by 1,2,4,5-benzenetetracarboxylic acid (H(4)btec), enantiomers (R)- and (S)-[Zn-3(pempH)(2)(btec)(H2O)(2)]center dot H2O (2) are obtained. Compounds 1 have a layer structure in which the chiral inorganic double chains, made up of corner-sharing {ZnO4} and {PO3C} tetrahedra, are connected by bdc(2-). While in compounds 2, chiral chains of zinc phosphonate are each connected to their four equivalent neighbors through btec(4-) linkages, resulting in an open framework structure. All these compounds are optically active, exhibiting second harmonic generation (SHG) responses 0.2 or 0.8 times that of urea.