Metal–Organic Frameworks (MOFs) as Multivalent Materials: Size Control and Surface Functionalization by Monovalent Capping Ligands

Control over particle size and composition are pivotal to tune the properties of metal organic frameworks (MOFs), for example, for biomedical applications. Particle-size control and functionalization of MIL-88A were achieved by using stoichiometric replacement of a small fraction of the divalent fumarate by monovalent capping ligands. A fluorine-capping ligand was used to quantify the surface coverage of capping ligand at the surface of MIL-88A. Size control at the nanoscale was achieved by using a monovalent carboxylic acid-functionalized poly(ethylene glycol) (PEG-COOH) ligand at different concentrations. Finally, a biotin–carboxylic acid capping ligand was used to functionalize MIL-88A to bind fluorescently labeled streptavidin as an example towards bioapplications.