CoII/ZnII-(L-Tyrosine) Magnetic Metal-Organic Frameworks

Three chiral coordination polymers assembled from L-tyrosine (L-tyr) and cobalt, cobalt/zinc and zinc salts, with a new three-dimensional (3D) structure and formulated as [M(L-tyr)]n (M = Co, Co/Zn, Zn) have been prepared by mild hydrothermal synthesis. These three compounds are isostructural, crystallize with monoclinic symmetry in the C2 space group and possess four crystallographically unique metal sites in tetrahedral (two) and octahedral (two) coordination environments resulting in two slightly distinct edge-sharing metal dimers with L-tyr linking the metal atoms in pillars. These features result in a dense framework. The study of the magnetic properties of the cobalt-bearing solid reveals a ferromagnetic exchange interaction within the Co2+ dimers. The racemic compound of dl-tyrosine and cobalt was also synthesized and its structure characterized.