A series of long-lived trans-substituted molybdenum dimers have been synthesized from a tetrakis Mo2(TiPB)4 precursor using carboxylate functionalized ligands of interest and where TiPB is 2,4,6-triisopropylbenzoate. These types of complexes have been known to possess long-lived triplet metal-centered excited states and broadly absorbing transitions due to strong metal-to-ligand charge transfer, MLCT. Excitation into these MLCT bands leads to lifetimes that outperform the commonly known photosensitizer benchmarks known to the field of light harvesting chromophores. Contrary to previously reported trans-substituted molecules, the current complexes are comprised of ligands including coumarin and perylene. These ligands possess low lying triplet excited states that now impart a third manifold into the excited state composition, which now include triplet MLCT, triplet metal-centered, and triplet ligand centered excited states, poised to mix and/or thermally equilibrate. With the use of UV-Vis absorbance, nanosecond transient absorption spectroscopy, and static photoluminescence spectroscopy in conjunction with temperature dependent measurements, the excited state behavior of these new chromophores have been evaluated. This presentation will include descriptions of these fascinating molecular excited states that will be contrasted with those of the relevant model chromophores.

Altering photophysics in trans-substituted molybdenum dimers using ligands featuring low energy triplet states

254th National Meeting (2017)

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