title: Blue Phosphorescent Zwitterionic Iridium(III) Complexes Featuring Weakly Coordinating nido-Carborane-Based Ligands.
abstract: We report the development of a new class of phosphorescent zwitterionic bis(heteroleptic) Ir(III) compounds containing pyridyl ligands with weakly coordinating nido-carboranyl substituents. Treatment of phenylpyridine-based Ir(III) precursors with C-substituted ortho-carboranylpyridines in 2-ethoxyethanol results in a facile carborane deboronation and the formation of robust and highly luminescent metal complexes. The resulting nido-carboranyl fragments associate with the cationic Ir(III) center through primarily electrostatic interactions. These compounds phosphoresce at blue wavelengths (450-470 nm) both in a poly(methyl methacrylate) (PMMA) matrix and in solution at 77 K. These complexes display structural stability at temperatures beyond 300 °C and quantum yields greater than 40%. Importantly, the observed quantum yields correspond to a dramatic 10-fold enhancement over the previously reported Ir(III) congeners featuring carboranyl-containing ligands in which the boron cluster is covalently attached to the metal. Ultimately, this work suggests that the use of a ligand framework containing a weakly coordinating anionic component can provide a new avenue for designing efficient Ir(III)-based phosphorescent emitters.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Axtell
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
authors.forename: Kent O
authors.initials: KO
authors.lastname: Kirlikovali
authors.affiliation: Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Peter I
authors.initials: PI
authors.lastname: Djurovich
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
authors.forename: Dahee
authors.initials: D
authors.lastname: Jung
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
authors.forename: Vinh T
authors.initials: VT
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Munekiyo
authors.affiliation: Department of Chemistry, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.|Department of Chemistry, University of West Florida , 11000 University Parkway, Pensacola, Florida 32514, United States.
authors.forename: A Timothy
authors.initials: AT
authors.lastname: Royappa
authors.affiliation: Department of Chemistry, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Rheingold
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095, United States.|California NanoSystems Institute (CNSI), University of California, Los Angeles , 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Spokoyny