Mn12 single-molecule magnets incorporated into mesoporous MCM-41 silica

Abstract

The incorporation of four Mn12 derivatives, namely [Mn12O12(O2CR)16(H2O)4] (R=CH3 (1), CH3CH2 (2), C6H5 (3), C6F5 (4)), into the hexagonal channels of the MCM-41 mesoporous silica have been studied. Only the smallest clusters 1 and 2 that are those with compatible size with the pores of MCM-41 could be incorporated into the mesoporous silica. Powder X-ray diffraction (XRD) analysis and N2 adsorption–desorption isotherm experiments show that the well-ordered hexagonal structure of MCM-41 is preserved and that the Mn12 clusters are inside the pores. The magnetic properties of the MCM-41/1 nanocomposite material indicate that the structure of the cluster is maintained after incorporation into the MCM-41 walls, but some differences appear that may be attributed to partial substitution of carboxylate groups of 1 by silanol groups of the wall surface. In contrast with the pristine Mn12 derivatives calcination of the composite samples gives rise to materials with similar properties to those observed before calcination.