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Improved Deep-Red Phosphorescence in Cyclometalated Iridium Complexes via Ancillary Ligand Modification

submitted on 25.10.2019, 20:07 and posted on 29.10.2019, 20:00 by Evanta Kabir, Steven Sittel, Boi-Lien Nguyen, Thomas Teets
In this work, we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence. Two different cyclometalating (C^N) ligands‒1-phenylisoquinoline (piq) and 2-(2- pyridyl)benzothiophene (btp)‒are used with six strong π-donating ancillary ligands (L^X) to furnish a suite of 10 new complexes with the general formula Ir(C^N)2(L^X). Improvements in deep-red photoluminescence quantum yields were accomplished by the incorporation of sterically encumbering substituents onto the ancillary ligand, which can enhance the radiative rate constant (kr) and/or reduce the non-radiative rate constant (knr). Five of the complexes were characterized by X-ray crystallography, and all of them were investigated by in-depth spectroscopic and electrochemical measurements.


National Science Foundation CHE-1846831

Welch Foundation E-1887


Email Address of Submitting Author


University of Houston


United States

ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest