Chirdon Danielle N, Transue Wesley J, Kagalwala Husain N, Kaur Aman, Maurer Andrew B, Pintauer Tomislav, Bernhard Stefan
Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
Inorg Chem. 2014 Feb 3;53(3):1487-99. doi: 10.1021/ic402411g. Epub 2014 Jan 17.
The relatively unexplored luminophore architecture Ir(N^N^N)(C^N)L (N^N^N = tridentate polypyridyl ligand, C^N = 2-phenylpyridine derivative, and L = monodentate anionic ligand) offers the stability of tridentate polypyridyl coordination along with the tunability of three independently variable ligands. Here, a new family of these luminophores has been prepared based on the previously reported compound Ir(tpy)(ppy)Cl (tpy = 2,2':6',2″-terpyridine and ppy = 2-phenylpyridine). Complexes are obtained as single stereoisomers, and ligand geometry is unambiguously assigned via X-ray crystallography. Electrochemical analysis of the materials reveals facile HOMO modulation through ppy functionalization and alteration of the monodentate ligand's field strength. Emission reflects similar modulation shifting from orange to greenish-blue upon replacement of chloride with cyanide. Many of the new compounds exhibit impressive room temperature phosphorescence with lifetimes near 3 μs and quantum yields reaching 28.6%. Application of the new luminophores as photosensitizers for photocatalytic hydrogen generation reveals that their photostability in coordinating solvent is enhanced as compared to popular Ir(ppy)2(bpy) (bpy = 2,2'-bipyridine) photosensitizers. Yet, the binding of their monodentate ligand emerges as a source of instability during the redox processes of cyclic voltammetry and mass spectrometry. DFT modeling of electronic structure is provided for all compounds to elucidate experimental properties.
相对未被充分探索的发光体结构Ir(N^N^N)(C^N)L（N^N^N = 三齿多吡啶配体，C^N = 2-苯基吡啶衍生物，L = 单齿阴离子配体）兼具三齿多吡啶配位的稳定性以及三种独立可变配体的可调性。在此，基于先前报道的化合物Ir(tpy)(ppy)Cl（tpy = 2,2':6',2″-三联吡啶，ppy = 2-苯基吡啶）制备了这一系列新的发光体。所得到的配合物为单一立体异构体，通过X射线晶体学明确确定了配体的几何结构。对这些材料的电化学分析表明，通过ppy官能化和改变单齿配体的场强可轻松实现最高占据分子轨道（HOMO）的调制。发射光谱显示出类似的调制，用氰化物取代氯化物后，发射光从橙色转变为绿蓝色。许多新化合物在室温下表现出令人印象深刻的磷光，寿命接近3 μs，量子产率达到28.6%。将新的发光体用作光催化产氢的光敏剂表明，与常用的Ir(ppy)2(bpy)（bpy = 2,2'-联吡啶）光敏剂相比，它们在配位溶剂中的光稳定性有所增强。然而，在循环伏安法和质谱的氧化还原过程中，它们单齿配体的结合成为不稳定性的一个来源。为所有化合物提供了电子结构的密度泛函理论（DFT）建模，以阐明实验性质。
