Bistridentate Ruthenium(II)polypyridyl-Type Complexes with Microsecond 3MLCT State Lifetimes: Sensitizers for Rod-Like Molecular Arrays
Bistridentate Ruthenium(II)polypyridyl-Type Complexes with Microsecond 3MLCT State Lifetimes: Sensitizers for Rod-Like Molecular Arrays
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DOI：
10.1021/ja804890k
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发表时间：
2008-11-19
影响因子：
15
通讯作者：
Hammarstrom, Leif
中科院分区：
文献类型：
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作者：
Abrahamsson, Maria;Jager, Michael;Hammarstrom, Leif
合成了一系列基于新型2，6-二（喹啉-8-基）吡啶（dqp）配体的双三齿多吡啶钌（II）配合物，并研究了它们的物理化学性质。配合物是适合取代在4-位的中央吡啶与保守的准C-2 V对称性，这允许扩展到异构体自由，棒状分子阵列的电子和能量转移的矢量控制。对母体[Ru（dqp）（2）]（2+）配合物（1）进行的DIFT计算预测，由于较大的配体咬合角，其比典型的双三齿配合物[Ru（tpy）（2）]（2+）（tpy是2，2 '：6'，2“-三联吡啶）具有更多的八面体结构，这通过X射线晶体学得到证实。一个强的可见光吸收带，在491 nm处的最大值被分配到金属到配体的电荷转移（MLCT）过渡，基于时间依赖性DIFT计算。1显示了从其最低激发态（（MLCT）-M-3）的室温发射（Phi = 0.02），该激发态具有非常长的寿命（τ = 3 μ s）。长寿命是由于更强的配体场，因为更多的八面体结构，这使得通过短寿命的金属中心态的通常占主导地位的活化衰变在升高的温度下也不重要。合成了一系列吡啶4位上带有给电子和/或接受电子取代基的dqp配合物，并与1。一个前所未有的（MLCT）-M-3态寿命为5.5 μ s的证明了基于dqpCO（2）Et的同配络合物。1的良好的光敏剂性质，如高消光系数，高激发态能量和长寿命，和可调的氧化还原电位，保持取代后。此外，母体配合物1被证明是显着的光稳定性，并显示出高的反应性，在光诱导的电子和能量转移反应与典型的能量和电子受体和供体：甲基紫精，四硫富瓦烯，和9，10-二苯基蒽。这类新的配合物构成了一个很有前途的起点，为建设线性，棒状分子阵列的光敏化反应和人工光合作用和分子电子学的应用。
A series of bistridentate ruthenium(II) polypyridyl-type complexes based on the novel 2,6-di(quinolin-8-yl)pyridine (dqp) ligand have been synthesized and their photophysical properties have been studied. The complexes are amenable to substitution in the 4-position of the central pyridine with conserved quasi-C-2v symmetry, which allows for extension to isomer-free, rod-like molecular arrays for vectorial control of electron and energy transfer. DIFT calculations performed on the parent [Ru(dqp)(2)](2+) complex (1) predicted a more octahedral structure than in the typical bistridentate complex [Ru(tpy)(2)](2+) (tpy is 2,2':6',2 ''-terpyridine) thanks to the larger ligand bite angle, which was confirmed by X-ray crystallography. A strong visible absorption band, with a maximum at 491 nm was assigned to a metal-to-ligand charge transfer (MLCT) transition, based on time-dependent DIFT calculations. 1 shows room temperature emission (Phi = 0.02) from its lowest excited ((MLCT)-M-3) state that has a very long lifetime (tau = 3 mu s). The long lifetime is due to a stronger ligand field, because of the more octahedral structure, which makes the often dominant activated decay via short-lived metal-centered states insignificant also at elevated temperatures. A series of complexes based on dqp with electron donating and/or accepting substituents in the 4-position of the pyridine was prepared and the properties were compared to those of 1. An unprecedented (MLCT)-M-3 state lifetime of 5.5 mu s was demonstrated for the homoleptic complex based on dqpCO(2)Et. The favorable photosensitizer properties of 1, such as a high extinction coefficient, high excited-state energy and long lifetime, and tunable redox potentials, are maintained upon substitution. In addition, the parent complex 1 is shown to be remarkably photostable and displays a high reactivity in light-induced electron and energy transfer reactions with typical energy and electron acceptors and donors: methylviologen, tetrathiofulvalene, and 9,10-diphenylanthracene. This new class of complexes constitutes a promising starting point for the construction of linear, rod-like molecular arrays for photosensitized reactions and applications in artificial photosynthesis and molecular electronics.