1. Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency (JST), 3-5 Sanbanchou, Chiyoda-ku, Tokyo 102-0075, Japan; Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226 8503, Japan; and Department of Chemistry and Materials Science, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan