Synthesis, characterization and magnetic properties of hollow microspheres with micro-mesoporous shells assembled from cobalt-based ferrocenyl coordination polymers.

Hollow magnetic microspheres with micro-mesoporous shells were constructed with layered cobalt-based ferrocenyl coordination polymers (Co-Fc-HCPS) through a one-step Ostwald ripening process. The diameters of microspheres and corresponding cavities were controlled in the range of several microns by tuning the reaction time and reactant concentration, which would attribute the microspheres with high loading, and enhanced mass diffusion and transfer efficiency. The high crystallinity of hollow microspheres allowed determination of the crystal structure of cobalt-based ferrocenyl coordination polymer, which crystallized in Brucite-type layered structure with the formula of Co(4)(OH)(4)(FcDC)(2), (H(2)FcDC=1,1'-ferrocenedicarboxylic acid), by combination of powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), element analysis (EA), and Fourier transform infrared spectroscopy (FT-IR). N(2) adsorption/desorption investigation revealed the existence of both mesopores around 3.81 nm and micropores of ca. 1 nm in the shells. The hollow microspheres exhibited spin-canted antiferromagnetism with weak ferromagnetic ordering below ~52 K, which showed a remanent magnetization (Mr) of 1.0 μ(B) and a large coercive field (Hc) of 5 kOe at 7 K.