Metal%3CU%2B2010%3Eorganic frameworks for radiation detection and particle discrimination.

Metal-organic frameworks (MOFs) represent a diverse and rapidly expanding class of materials comprising metal ions bridged by organic linker molecules. These robust crystalline structures have been found to exhibit exceptionally large surface areas, paving the way for diverse applications ranging from gas storage and separations to catalysis, drug delivery, and sensing. Less well understood are the intrinsic luminescence properties of MOFs, which arise from the electronic transitions within the hybrid metal-organic structure. Recently, we reported the observation of scintillation in stilbene-based MOFs, representing the discovery of the first completely new class of radiation detection materials since the advent of plastic scintillators in 1950. Photoluminescence and ion-induced luminescence spectroscopy of these materials show that both the luminescence spectrum and its timing can be varied by altering the local environment of the chromophore, establishing critical insight towards the rational design of materials for specific radiation detection applications. In this work, we describe the luminescence and scintillating properties of a series of isoreticular MOFs (IRMOFs), emphasizing the structural and electronic effects associated with systematic modification of the chromophore. Among these structures are IRMOFs based on naphthyl, biphenyl, terphenyl, and stilbene dicarboxylate linkers, for which unique structural changes and optical properties are observed. Inmore » addition to chemical changes in the structure, framework interpenetration may also be synthetically controlled, resulting in pairs of catenated and non-catenated IRMOFs based upon the same organic linker. The distinct interchromophore distances and solvate structure in these pairs lead to unique luminescence spectra that are interpreted in terms of energy transfer interactions. These spectral changes provide insight into the mechanism for radiation-induced luminescence, which for MOFs may differ significantly from the photoluminescence spectrum.« less