Zhang Guang, Baumgarten Martin, Schollmeyer Dieter, Müllen Klaus
Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz D-55128, Germany.
Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, China.
ACS Omega. 2018 Oct 22;3(10):13808-13816. doi: 10.1021/acsomega.8b01942. eCollection 2018 Oct 31.
New functionalized tris(2',6'-difluoro-2,3'-bipyridinato-,C4')iridium(III) ((dfpypy)Irs) complexes, including small molecules and their dendrimer embedded analogoues, were synthesized and characterized. It is demonstrated that both the -(dfpypy)Ir-based polyphenylene dendrimers and (triisopropylsilyl)ethynyl (TIPSE)-substituted (dfpypy)Ir complexes induce large bathochromic shifts (∼50 nm) of emission bands compared with -(dfpypy)Ir. This is due to the pronounced π-π* character of emissive excited states and the extended conjugation. A further remarkable feature is the small bathochromic shift of the emissions of -tris(2-phenylpyridine)iridium (-(ppy)Ir)-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 π-π* transition. This finding suggests new concepts for designing blue phosphorescent dendrimer emitters. Both the dendrimers and the TIPSE-substituted (dfpypy)Ir complexes represent new green and the trimethylsilyl-functionalized (dfpypy)Ir new blue phosphorescent emitters. Incorporation of TIPSE moieties into the ligands of iridium complex gives rise to enhanced phosphorescence.
合成并表征了新型功能化三（2'，6'-二氟-2，3'-联吡啶基，C4'）铱（III）（（dfpypy）Irs）配合物，包括小分子及其嵌入树枝状聚合物的类似物。结果表明，与-（dfpypy）Ir相比，基于-（dfpypy）Ir的聚亚苯基树枝状聚合物和（三异丙基甲硅烷基）乙炔基（TIPSE）取代的（dfpypy）Ir配合物均会导致发射带出现较大的红移（约50 nm）。这是由于发射激发态具有明显的π-π特性以及共轭的扩展。另一个显著特征是，与铱（Ir）配合物核心相比，基于-三（2-苯基吡啶）铱（-（ppy）Ir）的聚亚苯基树枝状聚合物的发射红移较小。显然，三重态金属到配体的电荷转移使发射对扩展共轭的敏感性低于π-π跃迁。这一发现为设计蓝色磷光树枝状聚合物发光体提出了新的概念。树枝状聚合物和TIPSE取代的（dfpypy）Ir配合物均代表了新型绿色发光体，而三甲基甲硅烷基功能化的（dfpypy）Ir则代表新型蓝色磷光发光体。将TIPSE部分引入铱配合物的配体中会增强磷光。
