School of Materials, Arizona State University, Tempe, Arizona 85287, United States.
Inorg Chem. 2010 Dec 20;49(24):11276-86. doi: 10.1021/ic100740e. Epub 2010 Nov 22.
In order to investigate the ground state and excited state properties of Pt(N(∧)C(∧)N)X, we have prepared a series of Pt complexes, where N(∧)C(∧)N aromatic chelates are derivatives of m-di(2-pyridinyl)benzene (dpb) and X are monoanionic and monodentate ancillary ligands including halide and phenoxide. Facile synthesis of platinum m-di(2-pyridinyl)benzene chloride and its derivatives, using controlled microwave heating, was reported. This method not only shortened the reaction time but also improved the reaction yield for most of the Pt complexes. Two Pt(N(∧)C(∧)N)X complexes have been structurally characterized by X-ray crystallography. The change of functional group does not affect the structure of the core Pt(N(∧)C(∧)N)Cl fragment. Both molecules pack as head-to-tail dimers, each molecule of the dimer related to the other by a center of inversion. The electrochemical studies of all Pt complexes demonstrate that the oxidation process occurs on the metal-phenyl fragment and the reduction process is associated with the electron accepting groups like pyridinyl groups and their derivatives. The maximum emission wavelength of the Pt(N(∧)C(∧)N)X complexes ranges between 471 and 610 nm, crossing the spectrum of visible light. Most of the Pt complexes are strongly luminescent (Φ = 0.32-0.63) and have short luminescence lifetimes (τ = 4-7 μs) at room temperature. The lowest excited state of the Pt(N(∧)C(∧)N)X complexes is identified as a dominant ligand-centered (3)π-π* state with some (1)MLCT/(3)MLCT character, which appears to have a larger (1)MLCT component than their bidentate and tridentate analogs. This results in a high radiative decay rate and high quantum yield for Pt(dpb)Cl and its analogs. However, the excited state properties of the Pt(N(∧)C(∧)N)X complexes are strongly dependent on the nature of the electron-accepting groups and substituents to the metal-phenyl fragment. A rational design will be needed to tune the emission energies of the Pt(N(∧)C(∧)N)X complexes over a wide range while maintaining their high luminescent efficiency.
为了研究 Pt(N(∧)C(∧)N)X 的基态和激发态性质，我们制备了一系列 Pt 配合物，其中 N(∧)C(∧)N 芳族螯合物是间二(2-吡啶基)苯(dpb)的衍生物，X 是单价和单齿辅助配体，包括卤化物和酚氧。我们报道了使用控制微波加热方便地合成铂间二(2-吡啶基)苯氯化物及其衍生物。这种方法不仅缩短了反应时间，而且提高了大多数 Pt 配合物的反应收率。通过 X 射线晶体学对两个 Pt(N(∧)C(∧)N)X 配合物进行了结构表征。功能基团的变化不影响核心 Pt(N(∧)C(∧)N)Cl 片段的结构。两个分子都以头尾二聚体的形式包装，每个二聚体分子通过中心反演相关。所有 Pt 配合物的电化学研究表明，氧化过程发生在金属-苯基片段上，还原过程与吡啶基及其衍生物等电子接受基团相关。Pt(N(∧)C(∧)N)X 配合物的最大发射波长范围在 471nm 到 610nm 之间，跨越可见光光谱。大多数 Pt 配合物具有很强的发光性（Φ=0.32-0.63），在室温下具有短的发光寿命（τ=4-7μs）。Pt(N(∧)C(∧)N)X 配合物的最低激发态被确定为以配体为中心的（3）π-π*态，具有一些（1）MLCT/(3)MLCT 特征，与它们的双齿和三齿类似物相比，具有更大的（1）MLCT 成分。这导致 Pt(dpb)Cl 及其类似物具有高辐射衰减率和高量子产率。然而，Pt(N(∧)C(∧)N)X 配合物的激发态性质强烈依赖于电子接受基团和金属-苯基片段的取代基的性质。需要进行合理的设计，以在保持高发光效率的同时，在较宽的范围内调节 Pt(N(∧)C(∧)N)X 配合物的发射能。
