1. Center for Molecular Design and Synthesis, Department of Chemistry and School of Molecular Science (BK-21), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-Dong, Yuseong-Gu, Daejeon 305-701, Korea, Department of Chemistry, Seonam University, Namwon 590-711, Korea, ICORP Entropy Control Project, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan, and Department of Molecular Chemistry, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan