Impact of Ligands on the Properties of Lanthanide Metal-Organic Frameworks

A series of lanthanide metal-organic frameworks (MOFs) have been assembled with a series of functionalized [1,1 ':4 ',1 ''-terphenyl]-4,4 ''-dicarboxylic acid ligands. The relationship between the ligand properties and the corresponding MOF properties has been studied. The structures of the MOFs depend on the solvent-ligand and ligand-ligand interactions, as well as the size of the non-coordinating functional groups of the ligands. The differences in thermal stability among the ligands are inherited and amplified by corresponding lanthanide MOFs. The ligands bearing methyl, ether, and aldehyde functional groups are capable of sensitizing the emission from the lanthanide centers, whereas the ligand with alpha,beta-unsaturated ketone functional groups are non-emissive due to the mismatch of the ligand and metal energy levels.