1. State Key Laboratory of Elemento-Organic Chemistry Tianjin Key Lab for Rare Earth Materials and Applications School of Materials Science and Engineering Nankai University Tianjin 300350 P. R. China
2. Department of Chemistry The University of Akron Akron OH 44325–3601 USA
3. College of Chemistry and Chemical Engineering Central South University Changsha 410083, Hunan P. R. China