| Budget Amount *help |
¥10,600,000 (Direct Cost: ¥10,600,000)
Fiscal Year 2004: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2003: ¥7,500,000 (Direct Cost: ¥7,500,000)
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| Research Abstract |
The design of structurally defined hybrid materials consisting of organic compounds and small metal species is one of the interesting subjects in materials science because of their inherently different natures and possible synergetic effects. Polyoxometalates, anionic clusters of early transition metal oxides, are attractive inorganic building blocks because of their discrete structures and notable acid-base, redox, and photochemical properties that lead to a vast range of applications. Recently, we have found that the tonic crystals composed of Keggin polyoxotungstate anion and sodium complex of calix[4]arene-adopt characteristic 3D packing structures, such as porous and monolayr-like domain-separated structures. However, these potentially useful crystalline materials were structurally unstable towards the thermal treatment that causes the elimination of the included solvate molecules. This observation motivated us to explore more structurally stable hybrid crystals by the molecular design of the calixarene units, and also attempt the interlocking the original packing structures by cross-linking among the calixarene units. In the present study, we found that the use of a calix[4]arene having two ethoxycarbonylmethoxy groups at the lower rim gave a an ionic crystal with thermally stable 1D micropores, to which small alcohols were preferentially trapped due to the amphiphilic pore environment. We also found that solid hybrid assemblies prepared from cimmamoyl-appended calixarenes gave, upon UV light irradiation, polyoxometalate-containing calixarene polymers as the result of soild-phase [2+2] photodimerization. Infrared studies revealed that the composition of the polymer product is almost identical to that before polymerization, indicating that the inorganic anions were trapped within the calixarene-polymer matrix.
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