Taira Nobuyuki, Saitoh Masashi, Hashimoto Shuichi, Moon Hyung Rang, Yoon Kyung Byung
Chemistry Department and Advanced Engineering Courses, Gunma College of Technology, Maebashi, Gunma 371-8530, Japan.
Photochem Photobiol Sci. 2006 Sep;5(9):822-7. doi: 10.1039/b605469b. Epub 2006 Jul 6.
We carried out time-resolved luminescence and transient absorption studies of tris(2,2'-bipyridine)ruthenium(ii) complex, Ru(bpy)3(2+) assembled in the supercages of zeolites X and Y exchanged with various alkali metal cations. The average lifetime of the luminescence decay, a measure of the photoinduced electron transfer (PET) rate, of Ru(bpy)3(2+)* was found to decrease with increasing the electron-acceptor strength of the host which is represented by the Sanderson's electronegativity scale. This result strongly suggests that the zeolite host plays the role of electron acceptor for Ru(bpy)3(2+)*. However, we could not detect Ru(bpy)3(3+) in the transient absorption spectra, most likely due to very low absorption coefficient of Ru(bpy)3(3+) and to the low efficiency of net PET. For the above observation to be made, it is essential to employ the dehydrated zeolite hosts to allow direct interaction between the guest Ru(ii) complex and the host framework. The present study demonstrates the active role of the zeolite hosts during the PET of incorporated Ru(bpy)3(2+) under the carefully controlled experimental conditions. This report demonstrates the fact that the zeolite hosts can serve as electron acceptors although in the past zeolites were shown to play the role of electron donors.
我们对组装在与各种碱金属阳离子进行交换的X型和Y型沸石超笼中的三（2,2'-联吡啶）钌（II）配合物Ru(bpy)₃²⁺进行了时间分辨发光和瞬态吸收研究。发现Ru(bpy)₃²⁺*的发光衰减平均寿命（光诱导电子转移（PET）速率的一种度量）随着以桑德森电负性标度表示的主体电子受体强度的增加而降低。该结果强烈表明沸石主体对Ru(bpy)₃²⁺*起到电子受体的作用。然而，我们在瞬态吸收光谱中未检测到Ru(bpy)₃³⁺，这很可能是由于Ru(bpy)₃³⁺的吸收系数非常低以及净PET效率较低。为了进行上述观察，使用脱水的沸石主体以使客体Ru（II）配合物与主体骨架之间能够直接相互作用至关重要。本研究证明了在精心控制的实验条件下，沸石主体在掺入的Ru(bpy)₃²⁺的PET过程中所起的积极作用。本报告证明了尽管过去沸石被证明起到电子供体的作用，但沸石主体可以作为电子受体这一事实。
