Ultrafast energy migration in porphyrin-based Metal Organic Frameworks (MOFs)

In this paper, we have studied the energy transport properties of two porphyrin-containing metal organic frameworks (MOFs) for light-harvesting applications. The photoinduced singlet exciton migration is investigated using fluorescence quenching experiments, whereas details on exciton transport anisotropy and net displacements are obtained using a Förster theory analysis. The striking difference in the energy-transport properties for the two MOFs, albeit for similar molecular organization, is attributed to dissimilar spatial expanse and difference in the electronic structure of their porphyrin struts. The observed exciton displacements, of up to 60 nm, provides motivation to explore new MOF materials. Several new linkers are considered, leading to predictions of MOF structures, which provide both broad-wavelength harvesting and unidirectional energy transporting MOFs with selected examples. (Figure Presented)