Histidine-controlled two-dimensional assembly of zinc phosphite four-ring units

Despite there being numerous examples of metal-organic frameworks in which metal centers or Clusters are joined together by bi- or polydentate ligands into extended structures, biologically important amino acids, histidine in particular, are rarely known to serve as bridging ligands for the construction of open-framework architectures. Here, we report hydrothermal self-assembly between neutral zwitterionic histidine molecules and inorganic secondary building units (i.e., (Zn-O-P-O)(2) four-rings) into a crystalline solid containing infinite two-dimensional arrays. We demonstrate that the acid-base and coordination chemistry of histidine can be controlled to promote the formation of open architectures with bridging histidine ligands instead of the commonly observed metal-chelates with chelating histidine ligands. Crystallographic data for Zn(HPO3)(DL-C6H9N3O2)(H2O)(1/2), C2/c, a = 15.1307(3) angstrom, b = 8.4230(2) angstrom, c = 16.6322(4) angstrom, beta = 100.420(1)degrees, V = 2084.75(8) angstrom(3), Z = 8.