Manipulating Lanthanide Luminescence in Metal-Organic Frameworks

The inclusion of lanthanides within Metal-Organic Framework (MOF) systems has been explored for a variety of reasons, including high coordination numbers and hard acidic properties. Still more interesting perhaps is the fact that lanthanides possess unique luminescent properties (i.e. – sharp emission peaks), which may lead to a variety of useful applications. However, the process by which lanthanides undergo luminescence is highly inefficient due to forbidden transitions as defined by Laporte selection rules. A common way to circumvent this problem is to sensitize the lanthanide luminescence via an unsaturated organic molecule conjugated to the metal center. We recently published a three-dimensional structure where a conjugated organic molecule, 4,4’-dipyrdiyl, resides in the channels uncoordinated to the metal. We explored the luminescence of this material and have shown that the 4,4’-dipyridyl does indeed sensitize lanthanide luminescence. We have explored and thus report herein the luminescence of GWMOF-6 ([Ln2(C6H8O4)3(H2O)2]•(C10H8N2)) (Ln = Eu3+ and Eu3+/Tb3+ (50/50)), and a Tb-only structure believed to be similar to GWMOF-6. Structural and synthetic details will also be reviewed