Effect of electron-acceptor strength of zeolite on the luminescence decay rate of Ru(bpy)_3^2+ incorporated within zeolites
Effect of electron-acceptor strength of zeolite on the luminescence decay rate of Ru(bpy)_3^2+ incorporated within zeolites
复制标题
沸石电子受体强度对沸石内Ru(bpy)_3^2发光衰减率的影响
DOI：
10.1039/b605469b
复制
发表时间：
2006
影响因子：
3.1
通讯作者：
K. B. Yoon
中科院分区：
文献类型：
--
作者：
Nobuyuki Taira;M. Saitoh;S. Hashimoto;H. Moon;K. B. Yoon
我们对三（2,2′-联吡啶）钌（II）配合物Ru(bpy)_3^2+在沸石X和Y的超笼中与各种碱金属阳离子交换进行了时间分辨率发光和瞬态吸收研究。Ru(bpy)_3^2+*的发光衰减平均寿命（光致电子转移速率的度量）随着主体电子受体强度的增加而减小，该强度由Sanderson电负性标度表示。这一结果有力地说明了沸石载体对Ru(bpy)_3^2+*起电子受体的作用。然而，我们无法在瞬态吸收光谱中检测到Ru(bpy)_3^3+，这很可能是由于Ru(bpy)_3^3+的吸收系数很低以及净PET的效率低。为了进行上述观察，必须使用脱水沸石基质，以允许客体Ru（II）配合物与主体框架之间的直接相互作用。本研究在精心控制的实验条件下，证明了沸石载体在掺入Ru(bpy)_3^2+的PET过程中的积极作用。该报告证明了沸石宿主可以作为电子受体的事实，尽管在过去沸石被证明起电子给体的作用。
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.