A composite magnetic matrix comprising a porous metal-organic framework (MOF) and a plurality of molecular magnets, where a plurality of pores of the MOF each comprise one of the plurality of molecular magnets, and where the each of the plurality of molecular magnets retains its magnetic properties in the matrix. The molecular magnet may be, for example, a single-molecule magnet or a single-chain magnet. For example, the composite magnetic matrix Mn12Ac@MOF comprises Mn12O12(O2CCH3)16(OH2)4 (Mn12Ac) as the single-molecule magnet and [Al(OH)(SDC)]n (H2SDC=4,4′-stilbenedicarboxylic acid) (CYCU-3) as the porous metal-organic framework.