1. Department of Chemistry, Korea University, 1 Anam-dong, Seoul, S. Korea 136-701, Department of Science Education, Chosun University, Kwangju, S. Korea 501-759, Department of Chemistry, The Catholic University of Korea, Pucheon, S. Korea, 420-743, and Department of Chemistry, Korea University, Jochiwon, Chungnam, S. Korea 339-700