Photophysical and Photochemical Investigations of New Tunable Luminescent Metal-Metal Bonded d8-d10 Exciplexes

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports Dr. Howard Patterson at the University of Maine at Orono to investigate d8-d10 exciplexes exhibiting multiple excimeric emissions that can be tuned across the UV and visible regions by: site-selective excitation, temperature, varying the concentration in solution or the solid state (alkali halide hosts), and/or controlled laser irradiation that leads to reversible write/read/erase changes. Photophysical, photochemical, and computational studies will be performed in order to assess the factors that are important for establishing structure-luminescence relationships in tunable systems. The broad tunability previously observed in d10-d10 complexes will be extended to d8-d10 exciplexes in order to determine the dependence of tunability on the following factors: a) cations of different charge (+1, +2, +3); b) different d8-d10 metal ions; c) complexes prepared from different solvents; and d) the thiocyanate ligand (SCN-) vs. cyanide (CN-) ligand. Photophysical energy transfer studies will be investigated between d8-d10 donor exciplexes and lanthanide ion acceptors. The photochemical reactions of the luminescent metal-metal bonded exciplexes will be studied in the solid state and doped in alkali halides at room and cryogenic temperatures. At the heart of the investigation are time-independent and time-resolved luminescence studies, thermal analysis, Raman scattering and infrared analysis, X-ray and neutron scattering structural studies, and electronic structure calculations. The project is expected to provide a) criteria for tunable systems with strong luminescence intensities; b) new luminescent exciplexes; and c) new insights into closed-shell metallophilic interactions. A better understanding of these factors will aid in the design of tunable solidstate systems for photonic applications. The results of this research will provide useful information that can lead to the design of new solid state tunable photonic systems and other useful devices based on the luminescent phenomena. Training of undergraduates, graduate students, and post-doctoral researchers in a variety of instruments and techniques that will be important in nanoscale science and engineering will also be provided through the proposed research.