Visual observation of contact-induced intercrystalline migration of aromatic species adsorbed in zeolites by fluorescence microscopy
Visual observation of contact-induced intercrystalline migration of aromatic species adsorbed in zeolites by fluorescence microscopy
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DOI：
10.1002/cphc.200400167
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发表时间：
2004-10-18
期刊：
影响因子：
2.9
通讯作者：
Yamashita, S
中科院分区：
文献类型：
--
作者：
Hashimoto, S;Yamashita, S
晶间迁移和迁移辅助化学反应的物理接触中的沸石颗粒之间的吸附的芳香族物质的可视化荧光显微镜结合粒子操作技术。利用特定沸石颗粒的发光颜色特性来跟踪分子的迁移，所述发光颜色特性源自吸附物种的特定光化学。两个例子是相关的时间依赖性的迁移过程的可视化：一个客人，两套沸石晶体系统：chrysophyll（Chry）-负载沸石Na+-X（沸石X的钠形式）晶体被放置在与未加载的Tl+-X（铊交换的X）晶体接触，并允许在室温下静置。最初，仅从Na+-X颗粒中检测到Chry的蓝色荧光，但随后，从Tl+-X中可辨别出绿色磷光发射的发展，这表明Chry从Na+-X迁移到Tl+-X晶体。两个客物种系统：将供电子Chry负载的Na+-X晶体与电子接受7，2，4，5-四氰基苯（TCNB）负载的Na+-X或Na+-Y晶体接触。随着时间的推移，前一体系（Chry/Na+-X和TCNB/Na+-X）产生的Chry-TCNB电荷转移复合物的发射主要来自Chry的迁移，而后一体系（Chry/Na+-X和TCNB/Na+-Y）产生的发射主要来自TCNB的迁移。本研究表明，客体的迁移有一定的方向，这取决于沸石主体和主客体或主客体相互作用的性质。
Intercrystalline migration and a migration-assisted chemical reaction of adsorbed aromatic species between zeolite particles in physical contact were visualized by fluorescence microscopy coupled with a particle manipulation technique. The luminescence color characteristics of particular zeolite particles originating from the specific photochemistry of adsorbed species was exploited to follow the migration of the molecules. Two examples are shown that are relevant to the visualization of the time-dependent migration process: A one guest-two sets of zeolite crystals system: chrysene (Chry)-loaded zeolite Na+-X (the sodium form of zeolite X) crystals were placed in contact with unloaded Tl+-X (thallium-exchanged X) crystals and allowed to stand at room temperature. Initially, the blue fluorescence of Chry was detected only from the Na+-X particles, but later, the development of green phosphorescence emission was discernible from the Tl+-X, which suggests that Chry migrated from the Na+-X to the Tl+-X crystals. A two guest-species systems: Electron-donating Chry-loaded Na+-X crystals were placed in contact with electron-accepting 7,2,4,5-tetracyanobenzene (TCNB)-loaded Na+-X or Na+-Y crystals. With time, the former system (Chry/Na+-X and TCNB/Na+-X) gave rise to the emission of Chry-TCNB charge-transfer complexes resulting mainly from the migration of Chry while the latter system (Chry/Na+-X and TCNB/Na+-Y) afforded the same emission resulting largely from the migration of TCNB. The present investigation reveals that there is a certain direction for guest migration depending on the zeolite host and the nature of host-guest or guest-guest interaction.