1. Department of Chemistry, School of Science, Kwansei-Gakuin University, Uegahara, Nishinomiya 662, Japan, Department of Physics, North-Eastern Hill University, Shillong-790322, India, Department of Chemistry, Faculty of Science and Engineering, Saga University, Saga 840, Japan, Mitsubishi Chemical Corporation, Yokohama Research Center, 1000 Kamoshida-cho, Aoba-ku, Yokohama 227, Japan, and Institute of DNA Medicine, The Jikei University School of Medicine, Nishi-shinbashi, Minato-ku, Tokyo 105, Japan