1. Research Centre for Spectrochemistry and Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Chemistry, Banaras Hindu University; Varanasi 221005, India, and Institute of Molecular Science and Department of Applied Chemistry, National Chiao Tung University; 1001 Ta Hsueh Road, Hsinchu 300, Taiwan