JAPAN NANONET BULLETIN - 42nd Issue - April 14, 2005

Design of defined hybrid assemblies composed of inorganic metal clusters and organic compounds

Nano-sized metal cluster compounds with sizes intermediate between molecules and bulk materials have been of considerable interest recently as building blocks for bottom-up approaches in nanotechnology because of properties such as quantum-size effects and specific surface structures. Currently, we are designing well-defined assemblies between organic compounds and metal nanoclusters through the use of supramolecular forces. Some of our projects include the design of 1) a single-cluster-confined organic cage architecture (Fig. 1), 2) a semiconductor cluster whose surface is modified by organic compounds with multiple functionalities, and 3) a polyoxometalate/organic composite crystal with unique superstructures (Fig. 2). In these systems, the inorganic multi-metal components are located in organic environments with unique chemical and physical properties, which can be fine-tuned since it is easy to modify the organic molecules. Considering the possible synergetic effects between the organic and inorganic components, these hybrid architectures have potential applications as novel catalysts and materials.

Fig. 1 Large Image
Possible structure of a hexaporphyrin cage confining a single Au55 cluster.

Fig. 2 Large Image
3D microporous network structure of a hybrid crystal composed of a Keggin polyoxotungstate and a calix[4]arene derivative.

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