Two series of metal-organic frameworks (MOFs) based on a flexible ligand and trivalent lanthanides were obtained hydrothermally in order to explore their optical properties at low temperature, magnetism, and catalytic activity in relation to their structural features. A multisite analysis was performed according to the 4f-4f transitions. Moreover, the heterogeneous catalytic activity of the series was evaluated in one-pot cyanosilylation with benzaldehyde as substrate. Recyclability, structure conservation, and catalytic efficiency were also evaluated and compared with those of analogous compounds.