Site-specific electronic couplings in dyads with MLCT excited states. Intramolecular energy transfer in isomeric Ru(ii)-Ru(ii) cyclometalated complexes
Site-specific electronic couplings in dyads with MLCT excited states. Intramolecular energy transfer in isomeric Ru(ii)-Ru(ii) cyclometalated complexes
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具有 MLCT 激发态的二元体中的位点特异性电子耦合。
DOI：
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发表时间：
2007
影响因子：
3.1
通讯作者：
F. Scandola
中科院分区：
文献类型：
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作者：
M. Polson;C. Chiorboli;S. Fracasso;F. Scandola
合成并表征了棒状双核配合物[（ttpy）Ru（tpy-ph_2-phbpy）Ru（ttpy）]^4+和[（ttpy）Ru（tpy-ph_2-tpy）Ru（phtbpy）]^4+。在这两种配合物中，多吡啶Ru（ii）中心具有（NNN）Ru（NNN）和（NNN）Ru（CNN）配位环境。这两种异构体的不同之处在于环化碳是位于桥上还是位于末端配体上。这两种复合物具有几乎相同的能级，但MLCT激发态的不同（桥接或终端）配体定位。因此，它们非常适合于研究激发态局部化对分子内能量转移动力学的可能影响。事实上，超快光谱测量产生不同的能量转移时间常数的两种异构体，与桥环化复合物（2.7 ps）比终端环化的一个（8.0 ps）更快。这种差异可以用Dexter能量转移的不同电子因素来解释。这项研究突出了涉及MLCT激发态的无机二联体中分子内能量转移的特殊复杂性。
The rod-like binuclear complexes [(ttpy)Ru(tpy-ph_2-phbpy)Ru(ttpy)]^4+ and [(ttpy)Ru(tpy-ph_2-tpy)Ru(phtbpy)]^4+ (for abbreviations, see text) have been synthesized and characterized. In both complexes, the polypyridine Ru( ii ) centers have (NNN)Ru(NNN) and (NNN)Ru(CNN) coordination environment. The two isomeric species differ in whether the cyclometalating carbon resides on the bridging or on the terminal ligand. The two complexes have virtually identical energy levels, but MLCT excited states of different (bridging or terminal) ligand localization. They are thus ideally suited to investigate possible effects of excited-state localization on intramolecular energy transfer kinetics. In fact, ultrafast spectroscopic measurements yield different energy transfer time constants for the two isomers, with the bridge-cyclometalated complex (2.7 ps) being faster than the terminal-cyclometalated one (8.0 ps). This difference can be explained in terms of different electronic factors for Dexter energy transfer. The study highlights the peculiar intricacies of intramolecular energy transfer in inorganic dyads involving MLCT excited states.