1. Department of Chemistry, Hanyang University, 17 Haengdang-Dong, Seongdong-Gu, Seoul 133-791, South Korea; Materials Center, Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, South Korea; and Environment and Energy Division 35-3, Korea Institute of Industrial Technology, Hongcheon, Ipjangmyeon, Cheonansi, Chungnam 330-825, South Korea