1. Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan, Facolta di Farmacia, Università degli Studi “G. D'Annunzio”, I-66100 Chieti, Italy, and Faculty of Chemistry, University of Wroclaw, 14, F. Joliot-Curie, 50-383 Wroclaw, Poland