The invention features metal-organic frameworks (MOFs) having a crystalline lattice comprising metallic nodes and organic ligands, wherein each organic ligand comprises a Lewis acidic or basic centre bound to N conjugated systems, wherein N is comprised between 2 and 5; said metallic nodes consist of metal ions or metal clusters located at the vertices of the crystalline lattice and coordinating said plurality of organic ligands; and said metallic nodes comprise metals of the rare-earth series.