Magnetic behavior of molecular magnets-based nanocomposite materials was investigated as a function of the molecular materials' concentration. These materials, made of transition metal ions connected via cyano-bridging ligands, Co-3[Fe(CN)(6)](2), were synthesized simultaneously with MSU-type mesoporous silica as a confinement matrix. This synergetic synthesis led to Co-3[Fe(CN)(6)](2) nanoparticles of ca. 2-3 nm. Their magnetic properties were investigated as a function of their concentration. These analyses, including dc and ac vs temperature, as well as frequency measurements, reveal a superspin-glass like transition at low temperature. The aging and memory effects observed demonstrate that the superspin-glass behavior for nanocomposites containing the lowest amount of nanoparticles is due principally to spin frustration on the surface of the nanoparticles while for the nanocomposites containing the largest amount of nanoparticles, both surface spin-frustration and dipolar interparticle interactions influence the magnetic regime. (C) 2011 Elsevier B.V. All rights reserved.