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

Abstract

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)].2H(2)O (). 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)(H(2)O)(2)].H(2)O () are obtained. Compounds have a layer structure in which the chiral inorganic double chains, made up of corner-sharing {ZnO(4)} and {PO(3)C} tetrahedra, are connected by bdc(2-). While in compounds , 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.