1. Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan
2. Department of Chemistry, College of Liberal Arts, University of Saga, Honjo-machi, Saga 840, Japan
3. Institute of DNA Medicine, The Jikei University School of Medicine, Nishi-Shinbashi, Minato-ku, Tokyo 105, Japan