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Study of Spectroscopic and Photochemical Behavior of Zeolite Supramolecules

沸石超分子的光谱和光化学行为研究

基本信息

批准号：
10640487
负责人：
KOJIMA Masanobu
金额：
$ 1.98万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

In order to elucidate the spectroscopic and photochemical behavior of guest molecules included in zeolite nanocavities, we (1) took the spectroscopic measurements of the BrΦnsted and Lewis acidities in the cavities, and studied (2) the dark reaction of aromatic alkenes caused by the BrΦnsted and Lewis acid sites, (3) the effects of alkali-metal cations in the cavities on the cis-trans photoisomerization of stilbene and azobenzene, and (4) the effects of alkali-metal cations in the cavities on the photooxygenation of aromatic alkenes. From these investigations, we obtained the following significant information about the cavities:1. Using 2-quinolone as a probe, the BrФnsted and Lewis acidities in the cavities were determined more precisely than by previous procedures such as the Hammett method.2. When electron-rich aromatic alkenes were adsorbed in proton-exchanged zeolites, their dark reaction proceeded readily due to the BrΦnsted and Lewis acid sites in the cavities. Therefore, it seems likely that alkali-metal cation exchanged zeolites are suitable photochemical reaction vessels for the alkenes.3. It was found that the co-adsorbed water in the cavities accelerated the above dark reactions.4. Due to the electrostatic interaction between guest molecules and metal cations in the cavities, the photodimerization of styrenes and the intramolecular cycloaddition of stilbenes were suppressed. As a result, the photooxygenation of the alkenes occurred more efficiently in the cavities than in solutions.5. It was found that the photochemical behavior of guest molecules adsorbed in the cavities depends on the site in which the molecules electrostatically interact with the metal cations.These results clearly indicate that the characteristics of zeolite cavities can be explained to regulate the photochemical behavior of guest molecules.

为了阐明沸石纳米腔中包含的客体分子的光谱和光化学行为，我们(1)对腔中BrΦnsted和Lewis酸进行了光谱测量，并研究了(2)BrΦnsted和Lewis酸位点引起的芳烃暗反应，(3)腔中碱金属阳离子对二苯乙烯和偶氮苯顺反光异构化的影响。(4)腔内碱金属阳离子对芳烃光氧化反应的影响。从这些调查中，我们获得了以下关于蛀牙的重要信息：使用2-喹诺酮作为探针，比以前的方法（如Hammett方法）更精确地测定了腔中的BrФnsted和Lewis酸。当富电子芳烃被吸附在质子交换的沸石中时，由于孔洞中的BrΦnsted和Lewis酸位点，它们的暗反应很容易进行。因此，碱金属阳离子交换沸石很可能是适合烯烃的光化学反应容器。结果表明，空腔中共吸附的水加速了上述暗反应的发生。由于客体分子与腔内金属阳离子之间的静电相互作用，苯乙烯的光二聚化和二苯乙烯的分子内环加成被抑制。结果，烯烃的光氧化作用在空腔中比在溶液中更有效地发生。研究发现，吸附在空腔中的客体分子的光化学行为取决于分子与金属阳离子静电相互作用的位置。这些结果清楚地表明，可以解释沸石空腔的特性来调节客体分子的光化学行为。