Three-state light switch of [Ru(phen)2dppz]2+:: Distinct excited-state species with two, one, or no hydrogen bonds from solvent
Three-state light switch of [Ru(phen)2dppz]2+:: Distinct excited-state species with two, one, or no hydrogen bonds from solvent
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DOI：
10.1021/jp037967k
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发表时间：
2004-05-20
影响因子：
2.9
通讯作者：
Lincoln, P
中科院分区：
文献类型：
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作者：
Olofsson, J;Önfelt, B;Lincoln, P
dppz（联吡啶并[3，2-a：2 '，3'-c]吩嗪）的钌配合物由于其环境敏感的发光而引起广泛的兴趣，并被用作例如DNA的光谱探针。用荧光光谱和单光子计数法研究了“光开关”配合物[Ru（phen）（2）dppz]（2+）（phen = 1，10-菲咯啉）在水、甘油、乙二醇、1，2-和1，3-丙二醇中激发态的失活过程.在所有的溶剂中发现异常的温度依赖性（增加量子产率和激发态寿命随温度的升高）。模型独立的分析表明，只有两个发射物种，溶剂和温度不变的发射光谱的配置文件，是足以占所有的数据在多元醇溶剂。在所有溶剂中，两种物质的比例的Van't霍夫图在较高温度下呈线性，表明两种物质快速热平衡，但在最粘稠的溶剂甘油中温度较低除外。具有正阿伦尼乌斯活化能的微观速率常数的系统的动力学建模需要第三个非发射物质，该物质被分配到与溶剂具有两个氢键的激发态，而前两个物质被分配到单氢键和非氢键激发态物质。-键合激发态物质。高纯度[Ru（phen）（2）dppz]（2+）在水溶液中的发光强度随温度的升高而增加，但没有波长漂移，这一发现支持了上述结论。
The ruthenium complexes of dppz (dipyrido[3,2-a:2',3'-c]phenazine) have found wide interest due to their environment-sensitive luminescence and are used, for example, as spectroscopic probes for DNA. The deactivation process for the excited state of the "light-switch" complex [Ru(phen)(2)dppz](2+) (phen = 1,10-phenanthroline) has been studied in water, glycerol, ethylene glycol, and 1,2- and 1,3-propandiol by using fluorescence spectroscopy and single photon counting. In all solvents anomalous temperature dependence is found (increasing quantum yield and excited-state lifetime with increasing temperature). Model-independent analysis shows that only two emissive species, with solvent- and temperature-invariant emission spectral profiles, are sufficient to account for all the data in the polyol solvents. Van't Hoff plots of the ratio of the two species are linear at higher temperatures in all solvents, indicating rapid thermal equilibration of the two species, except for lower temperatures in the most viscous solvent glycerol. Kinetic modeling of the system with microscopic rate constants with positive Arrhenius activation energies requires a third nonemissive species, which is assigned to an excited state with two hydrogen bonds from the solvent, whereas the first two species are assigned to the mono-hydrogen-bonded and non-hydrogen-bonded excited-state species. This assignment is supported by the observation of a growing luminescence intensity as temperature is increased, but no wavelength shift, of high-purity [Ru(phen)(2)dppz](2+) in water solution.