The molecular mechanism of dual emission in terpyridine transition metal complexes--ultrafast investigations of photoinduced dynamics.
The molecular mechanism of dual emission in terpyridine transition metal complexes--ultrafast investigations of photoinduced dynamics.
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三联吡啶过渡金属配合物双发射的分子机制——光致动力学的超快研究。
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发表时间：
2011
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影响因子：
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通讯作者：
J. Popp
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作者：
Ronald Siebert;A. Winter;U. Schubert;B. Dietzek;J. Popp
温度依赖性发光实验与飞秒时间分辨瞬态吸收光谱相结合，破译了在配体框架内具有共轭发色团的单核铁、钌和氧三吡啶配合物的光诱导激发态弛豫途径。本文提出的配合物构成了一类配位化合物，克服了大多数三联吡啶过渡金属配合物通常观察到的较差的发射性质。如前所述，配合物在室温下显示出由配体中心和金属到配体的电荷转移态引起的双重发射。本文对室温双发光的分子机理进行了实验研究。实验结果表明，在配体中心S(1)态的光激发下，激发态流形内发生了超快分支反应。这种分支发生在靠近frank - condon吸收点的“热”激发态几何结构中，并且在~ 100 fs内，即我们的实验装置的时间分辨率。超快微分吸收实验和温度相关发光数据的结合不仅可以得出关于观察到的双发射的分子机制的结论，而且还可以构建定量的雅布隆斯基图，从而详细描述确定现有系统显着发光特性的激发态拓扑。
Temperature dependent luminescence experiments are combined with femtosecond time-resolved transient absorption spectroscopy to decipher the photoinduced excited-state relaxation pathway in mononuclear Fe, Ru and Os terpyridine complexes bearing a conjugated chromophore within the ligand framework. The herein presented complexes constitute a class of coordination compounds, which overcome the poor emission properties commonly observed for most terpyridine transition metal complexes. As reported earlier, the complexes reveal dual emission at room temperature stemming from ligand centered and metal-to-ligand charge-transfer states. The molecular mechanism of the room temperature dual luminescence is addressed experimentally in this contribution. The experimental results indicate an ultrafast branching reaction within the excited-state manifold upon photoexcitation of the ligand-centered S(1) state. This branching occurs from a "hot" excited state geometry close to the Franck-Condon point of absorption and within ∼100 fs, i.e. the temporal resolution of our experimental setup. The combination of ultrafast differential absorption experiments and temperature-dependent luminescence data allows not only to draw conclusions about the molecular mechanism underlying the observed dual emission but also to construct quantitative Jablonski diagrams and, thereby, to detail the excited-state topology determining the remarkable luminescence properties of the systems at hand.