Excited-State Dynamics of Iridium(III): Applications in Chemistry



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Iridium has over the last half-century proven to be a critical material necessary to sustain many of the technologies of our modern world. Iridium’s uses in optoelectronic and photonic applications has caused this element to see a rapid increase in scholarship and study particularly of Iridium(III) organometallic complexes. This dissertation presents a series of Iridium(III) organometallic complexes ranging from luminescent supramolecular self-assembled coordination cages to cyclometalated cationic bis-isocyanide complexes with strong nonlinear absorption properties. The investigated compounds were characterized physically with NMR, FTIR, and mass spectrometry with select compounds structurally validated by single-crystal X-ray diffraction. All compounds were thoroughly photophysically characterized with a combination of UV-vis, steady-state photoluminescence spectroscopy, and time-resolved photoluminescence spectroscopy, with transient absorption being utilized to gain insight into the nonlinear optical characteristics of the bis-isocyanide complexes. The supramolecular coordination cages displayed increased contribution of bridging ligands into the emissive state as the triplet energy of the cyclometalated iridium nodes increased and the bridging ligand gained conjugation. This led to some complexes possessing an uncharacteristic bridge ligand centered emissive state. The cyclometalated bis-isocyanide complexes showed panchromatic excited-state absorption with in a 400 nm – 900 nm spectra window, with long-lived excited states. The addition of pyrene acceptor motifs on some of these bis-isocyanides produced complexes with the ability to tune ground and excited-state properties independently, a property which can be utilized to produce more robust nonlinear chromophores.



Iridium, Luminescence, Nonlinear optics, Photochemistry


Portions of this document appear in: Olumba, Morris E., Hanah Na, Alan E. Friedman, and Thomas S. Teets. "Coordination-Driven Self-Assembly of Cyclometalated Iridium Squares Using Linear Aromatic Diisocyanides." Inorganic Chemistry 60, no. 8 (2021): 5898-5907; and in: Olumba, Morris E., Ryan M. O’Donnell, Thomas N. Rohrabaugh Jr, and Thomas S. Teets. "Panchromatic Excited-State Absorption in Bis-Cyclometalated Iridium Isocyanide Complexes." Inorganic Chemistry 61, no. 48 (2022): 19344-19353.