Powders and thin films of the water-stable zirconium-based metal organic framework, UiO-67, have been doped with a photoactive Ru(II)(bpy)3, RuBPY, derivative ruthenium(II) bis-(2,2´-bipyridyl) (5,5´-dicarboxy-2,2´-bipyridyl) dichloride, RuDCBPY, ligand. The photophysics of the doped powders and films have been characterized as a function of RuDCBPY doping concentration. It was found that the mono-exponential 1.4μs emission lifetime of the metal centers decreases with increased doping concentration due to homogeneous energy transfer between RuDCBPY in the material in which the energy transfer rate constant is characterized by a distance dependence of approximately R4. At doping concentrations larger than 16 mm the emission lifetime decay is best characterized by a bi-exponential fit composed of a concentration sensitive long-lifetime component (~100-200 ns) and a concentration insensitive short-lifetime component (~20 ns). A doping scheme is proposed in which the longer lifetime component corresponds to RuDCBPY incorporated into the backbone of the framework and the shorter lifetime component corresponds to encapsulated RuDCBPY. To test this, an isostructural UiO-67 MOF was synthesized using bipyridyl-dicarboxylate ligands in place of biphenyldicarboxylate, UiO-67-DCBPY, and the material doped with Ru(II) bis-(2,2´-bipyridyl) dichloride post-synthetically. The result was materials densely doped with RuDCBPY (&gt; 50 mm) with average emission lifetimes of ~ 200 ns. Thin films of the post-synthetically doped materials have also been grown on TiO2 and show promise as dye sensitized solar cells.

Homogeneous energy transfer between Ruthenium(II) bis-(2,2’-bipyridyl) (5,5’-dicarboxy-2,2’-bipyridyl) metal centers doped into a zirconium(IV)-based metal-organic framework and its application as a DSSC

249th National Meeting (2015)

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