Photochemical reaction dynamics of molecules adsorbed into zeolites as revealed by time-resolved spectroscopic techniques.

1. 芳烃与沸石相互作用的荧光光谱研究荧光光谱结果揭示了蒽吸附在沸石上的显著行为，这取决于沸石的负载水平、水化状态以及沸石的化学组成。在脱水的NaX和NaY分子筛框架中，蒽分子与Na^+离子络合，并在高负载水平上络合。它们在Na^+离子的作用下形成二聚体。此外，我们的荧光光谱研究显示，在大量水和其他溶剂分子存在的情况下，在相对较高的负载下形成了蒽晶体。因此，我们发现，在沸石超笼中，访客芳香分子的动态行为严重依赖于沸石框架、访客物种和共吸附物之间相互作用的平衡。特别是共吸附水。我们发现，在足够低的蒽负载水平下，衰减率与水、甲醇和吡啶的量有关，而正己烷对其影响不大。三重态衰减速率的增强可归因于自猝灭事件，即基态蒽猝灭三重态。由此可见，当沸石腔中含有足够数量的共吸附溶剂，以屏蔽预期吸附蒽的阳离子位置时，蒽分子具有高度的可移动性。客体的高迁移率可能是由于少量对沸石骨架具有强亲和力的溶剂分子的作用释放了蒽与沸石壁的吸附相互作用。相反，大量的共吸附溶剂预计会干扰笼网中蒽的运动，因为它们是如此拥挤，足以填满笼间相互连接的窗口以及笼的很大一部分体积。分子筛中的分子扩散系数本文提出了一种新的基于光化学的实验方法来测定芳香物质在分子筛上吸附的扩散常数。该技术基本上观察了脉冲激光辐照产生的激发探针的淬火动力学。所述探针分子要么失活，要么被笼状网络内迁移的另一分子（猝灭剂）猝灭。采用连续时间随机游走（CTRW）模型对淬火动力学进行了分析。除了估算了蒽和唑烯在NaY中的扩散系数外，本研究还显示了相邻笼中分子之间的远程反应，反映了笼网的开放式结构。少

1. Flurescence Spectroscopic Investigation of the Interaction of aromatics with ZeolitesThe fluorescence spectroscopic results revealed a remarkable behavior of anthracene adsorbed into zeolites depending on the loading level and the state of hydration of the zeolites as well as the chemical composition of the zeolites. Anthracene molecules are suggested to be complexed with Na^+ ions in the zeolite frameworks of dehydrated NaX and NaY, and at high loading levels. they form dimers under the influence of Na^+ ion. Additionally, our fluorescence spectroscopic investigation revealed the formation of anthracene crystals at relatively high loadings in the presence of a large amount of water and other solvent molecules. Thus we found that the dynamic behavior of the guest aromatic molecules within the zeolite supercages are critically dependent upon the balance of interactions among the zeolite frameworks, guest species and coadsorbates. especially coadsorbed water.2. Effect of Coadsorbed So … More lventsWe found that at a sufficiently low loading level of anthracene the decay rate is dependent on the amount of water, methanol and pyridine but scarcely affected by n-hexane. The enhanced triplet decay rate was found to be ascribable to a self-quenching event, i.e. the triplet quenching by ground-state anthracene. Thus a picture was given that anthracene molecules are highly mobile when the zeolite cavities are loaded with the coadsorbed solvents in quantities sufficient to shield the cationic sites at which anthracene is supposed to be adsorbed. The high mobility of the guest species is presumably caused by the liberation of adsorption interaction of anthracene with the zeolite walls by the action of small quantities of the solvent molecules with strong affinity towards the zeolite frameworks. On the contrary, large quantities of the coadsorbed solvens are expected to interfere with the movement of anthracene in the cage networks because they are so crowded enough to fill the interconnecting windows between cages as well as a large portion of the cage volume.3. Molecular Diffusivity in ZeolitesWe present a new experimental technique based on photochemistry for acquiring diffusion constants of aromatic species adsorbed in zeolites. The technique basically observes the quenching kinetics of excited probes produced by the pulsed-laser irradiation. The probe molecules are expected either to deactivate or to undergo quenching by another molecule (a quencher) migrating within the cage networks. The quenching kinetics were analyzed by applying the CTRW (continuous time random walk) model. In addition to the estimation of the diffusion coefficient for anthracene and azulene in NaY, the present study showed the indication of the long-range reaction between molecules residing in the neighboring cages, reflecting open structure of the cage network. Less