Abstract: Luminescence color tuning is an area of great interest to materials research due to the expanding role of emissive complexes in a variety of optoelectronic and photocatalytic applications. This thesis contains an examination of structure-property relationships with luminescent iridium(III) complexes in order to synthetically control their photophysical and electrochemical properties and to optimize their performance in diverse fields, such as organic light-emitting diodes (OLEDs), photochemical water splitting, and chiroptical materials. A combinatorial approach was developed to accelerate the discovery of useful luminophores, and over 300 heteroleptic iridium(III) complexes have been prepared and characterized for their photophysical properties. Considerable attention has been placed on interpreting the effect of structural modifications at the ligand periphery and will be discussed in the context of tailoring the luminescent behavior of novel materials. An area that has seen tremendous growth throughout the tenure of this work is the field of OLED devices. Single-layer electroluminescent device constructed with an iridium(III) complexes were observed for the first time, and the color of these devices was tuned from yellow (λ_max = 560 nm) to blue-green (λ_max = 500 nm) by strategically modifying the iridium(III) luminophore. A computational method for predicting the emission energy of novel materials was also developed and will be discussed. A second field into which this work has endeavored is the area of photoinduced hydrogen production, specifically the design and optimization of iridium(III) photocatalysts for reducing protons to molecular hydrogen. Seven iridium(III) complexes were examined as photosensitizers, and a material expressing a nearly 100-fold increase in its ability to catalyze hydrogen production over Ru(bpy) ₃2+ is reported. A final extension of this work examined the chiroptical properties of enantiomerically pure iridium(III) complexes in order to increase their emission dissymmetry. Synthetic control was employed to predetermine helicality at the metal center and to influence the degree of circularly polarized light expressed by heteroleptic iridium(III) complexes. Early results suggest a correlation between photophysical properties and emission dissymmetry.