1. Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), School of Chemistry & Chemical Engineering of Guangxi Normal University, Guilin 541004, P.R. China
2. Laboratoire de Chimie de Coordination Organique, CNRS-UMR7140, Université de Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg Cedex, France