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 magnetic materials is
described. The structures of Co4(SO4)(OH)6(C2N2H8)0.5·3H2O and Co4(SO4)(OH)6(C6N2H12)0.5·H2O and their
thermal stability can be tailored via the choice of organic pillar. The interactions between the pillaring agent
and the compositionally complex inorganic layer are discussed. The influences of two pillaring agents i.e., the
flexible ethylenediamine and the relatively rigid 1,4-diazabicyclo[2,2,2]octane, on thermal stability, rigidity
upon guest loss, and magnetic behavior of the pillared solids are compared. The magnetism of the pillared
layered cobalt hydroxides is complex due to the influences of multiple metal sites, inter- and intralayer exchange,
spin−orbit coupling, and geometrical frustration. The wide variety of potential pillars, oxyanions, and possible
metal substitutions at the octahedral and tetrahedral sites offers the possibility of tailoring the magnetic and
porous properties of these materials.