Strategies to Optimize Photophysical Properties in Cyclometalated Iridium Complexes

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In the past 50 years, iridium has become an indispensable material that supports various technologies that power our modern world. Recently, there has been a growing interest in iridium(III) organometallic complexes for their optoelectronic applications. This thesis delves into the synthesis, structural characterization, and photophysical properties of several new iridium-based complexes. The research is divided into six sections, each contributing to our understanding of the versatile applications and unique characteristics of these compounds. Chapter 1 provides an overview of iridium(III) coordination chemistry, including its potential uses and challenges. Chapter 2 focuses on formazans, nitrogen-rich conjugated compounds, and their use as metalloligands in the assembly of polynuclear complexes. Chapter 3 investigates a series of neutral Chugaev-type chelating dicarbene iridium complexes with diverse cyclometalating ligands. In Chapter 4, the reactivity of bis-cyclometalated iridium bis-isocyanide complexes with azides is explored, which results in luminescent structures that depend on the aryl isocyanide substituents. Chapter 5 introduces a series of red and deep-red emitting heteroleptic bis-cyclometalated iridium(III) complexes with salicylaldimine and 2-picolinamide ancillary ligands. These complexes offer control over energy levels and emission color profiles. Lastly, Chapter 6 investigates the influence of coordination modes on emission properties. Overall, this thesis presents valuable insights into the design of iridium complexes, their potential significance in optoelectronic technologies, and their unique photophysical properties. It makes a significant contribution to the field of coordination chemistry and materials science.

Cyclometalated iridium, Phosphorescence, Photoluminescence, Quantum yield, Carbene ligands
Portions of this document appear in: Jiang, Chenggang, and Thomas S. Teets. "Trimetallic Iridium–Nickel–Iridium Bis (formazanate) Assemblies." Inorganic Chemistry 61, no. 23 (2022): 8788-8796; and in: Jiang, C. "Cañada, LM; Nguyen, NB; Halamicek, MDS; Nguyen, SH; Teets, TS Substituent-Dependent Azide Addition to Isocyanides Generates Strongly Luminescent Iridium Complexes." J. Am. Chem. Soc 145 (2023): 1227-1235; and in: Jiang, Chenggang, Sungwon Yoon, Yennie H. Nguyen, and Thomas S. Teets. "Modular Imine Chelates with Variable Anionic Donors Promote Red Phosphorescence in Cyclometalated Iridium Complexes." Inorganic Chemistry 62, no. 28 (2023): 11278-11286.