Layered cobalt hydroxysulfates with both rigid and flexible organic pillars: Synthesis, structure, porosity, and cooperative magnetism

The synthesis and characterization of two members of a family of porous mag netic materials is described. The structures of Co-4(SO4)(OH)(6)(C2N2H8)(0. 5). 3H(2)0 and Co-4(SO4)(OH)(6)(C6N2H12)(0.5).H2O and their thermal stabili ty can be tailored via the choice of organic pillar. The interactions betwe en the pillaring agent and the compositionally complex inorganic layer are discussed. The influences of two pillaring agents i.e., the flexible ethyle nediamine and the relatively rigid 1,4-diazabicyclo[2,2,2]octane, on therma l stability, rigidity upon guest loss, and magnetic behavior of the pillare d solids are compared. The magnetism of the pillared layered cobalt hydroxi des is complex due to the influences of multiple metal sites, inter- and in tralayer exchange, spin-orbit coupling, and geometrical frustration. The wi de variety of potential pillars, oxyanions, and possible metal substitution s at the octahedral and tetrahedral sites offers the possibility of tailori ng the magnetic and porous properties, of these materials.