Construction of mixed carboxylate and pyrogallate building units for luminescent metal-organic frameworks

A metal-organic framework, Ce-FDM-50, was constructed by employing gallic acid featuring both carboxylate and pyrogallate as the coordinating sites and Ce(III). The co-assembly of the carboxylates and pyrogallates with two metal ions have achieved a new type of paddle wheel secondary building unit. These building units were further joined by organic struts to obtain frameworks in sql topology. This synthetic approach could be expanded to five different lanthanide metals (Nd, Eu, Gd, Tb, Yb) for the construction of a series of isoreticular MOFs based on FDM-50, and even MTV-MOFs in which mixed lanthanide metals with specific ratios were distributed. In addition, featuring the lanthanide metals as the inorganic nodes in the network, Tb-FDM-50 showed distinct luminescence properties that could be furtherly tuned for variable applications.