Tailoring the Emission of Fluorinated Bipyridine-Chelated Iridium Complexes.
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ABSTRACT: New functionalized tris(2',6'-difluoro-2,3'-bipyridinato-N,C4')iridium(III) ((dfpypy)3Irs) complexes, including small molecules and their dendrimer embedded analogoues, were synthesized and characterized. It is demonstrated that both the fac-(dfpypy)3Ir-based polyphenylene dendrimers and (triisopropylsilyl)ethynyl (TIPSE)-substituted (dfpypy)3Ir complexes induce large bathochromic shifts (?50 nm) of emission bands compared with fac-(dfpypy)3Ir. This is due to the pronounced 3?-?* character of emissive excited states and the extended conjugation. A further remarkable feature is the small bathochromic shift of the emissions of fac-tris(2-phenylpyridine)iridium (fac-(ppy)3Ir)-based polyphenylene dendrimers when compared to those of the iridium (Ir) complex core. Obviously, the triplet metal-to-ligand charge transfer makes emission less sensitive to extended conjugation than the 3?-?* transition. This finding suggests new concepts for designing blue phosphorescent dendrimer emitters. Both the dendrimers and the TIPSE-substituted (dfpypy)3Ir complexes represent new green and the trimethylsilyl-functionalized (dfpypy)3Ir new blue phosphorescent emitters. Incorporation of TIPSE moieties into the ligands of iridium complex gives rise to enhanced phosphorescence.
SUBMITTER: Zhang G
PROVIDER: S-EPMC6644421 | biostudies-literature | 2018 Oct
REPOSITORIES: biostudies-literature
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