Study of Spectroscopic and Photochemical Behavior of Zeolite Supramolecules

为了阐明沸石纳米空穴中客体分子的光谱和光化学行为，我们（1）对空穴中的BrΦnsted和刘易斯酸进行了光谱测量，并研究了（2）由BrΦnsted和刘易斯酸中心引起的芳香烯烃的暗反应，（3）空穴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）空穴中碱金属阳离子对芳香烯烃光氧化反应的影响。从这些研究中，我们获得了以下重要信息的空腔：1。以2-喹诺酮为探针，比Hammett法等方法更精确地测定了牙洞内的Br nsted和刘易斯酸度.当富电子芳香烯烃吸附在质子交换沸石中时，由于空穴中的BrΦnsted酸中心和刘易斯酸中心，它们的暗反应易于进行。因此，碱金属阳离子交换沸石可能是烯烃的合适光化学反应容器.研究发现，空穴中的共吸附水加速了上述暗反应.由于空穴中客体分子与金属阳离子之间的静电相互作用，苯乙烯的光二聚反应和二苯乙烯的分子内环加成反应受到抑制。结果表明，在空穴中烯烃的光氧化反应比在溶液中更有效.发现吸附在空穴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作用的位置，这些结果清楚地表明沸石空穴的特性可以解释为对客体分子光化学行为的调节。

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.