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) Å, b = 8.4230(2) Å, c = 16.6322(4) Å, β = 100.420(1)°, V = 2084.75(8) Å3, Z = 8.