1. Department of Chemistry and State Key Laboratory of Physical Chemistry for Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (P. R. China), Fax: (+86) 592‐2185192
2. Nantong Huafeng Chemical Co. Ltd., Nantong, Jiangsu, 226531 (P. R. China)