PHOTOCHEMICAL ENERGY-STORAGE IN A SPATIALLY ORGANIZED ZEOLITE-BASED PHOTOREDOX SYSTEM

Zeolites are often employed as organizational media or supports for en trapped or adsorbed transition-metal catalysts and photocatalysts(1-6) . In such applications, the individual catalytic species have been ass ociated with the framework structure of the zeolite in a purely statis tical (randomized) arrangement A synthetic strategy developed recently (7) has shown how a much higher level of organization can be obtained, so pointing the way to the generation of systems in which two or more active components can be arranged-both spatially and in terms of reac tivity-within the zeolite host to enhance the efficiency of a desired catalytic reaction. Here ive describe an application of this approach to photochemical storage of light energy. Such an application requires efficient photoinduced charge transfer between donor and acceptor mol ecules to form long-lived charge-separated states: the competing therm al back electron transfer reaction must be minimized, This is achieved in our system by arranging the active components (donor, acceptor and a 'sensitizing' intermediate molecule) such that they occupy adjacent cages within the zeolite framework and results in unprecedented level s of net charge-separation efficiency.