1. Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
2. Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712-1224, USA
3. InnovoTEX, Inc. 3800 N. Lamar Blvd, Austin, Texas 78756, USA
4. Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, P. R. China
5. Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, P. R. China