1. Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea, Korea Research Institute of Standards and Science, Daejeon 305-600, Korea, Department of Chemistry, Sogang University, Seoul 121-742, Korea, Department of Chemistry, Dong-Eui University, Busan 614-714, Korea, and Department of Chemistry, Chungnam National University, Daejeon 305-764, Korea