1. Organic and Carbon Nanomaterials Unit Okinawa Institute of Science and Technology Graduate University 1919‐1 Tancha, Onna‐son Kunigami‐gun Okinawa 904‐0495 Japan
2. Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing 100190 P. R. China
3. College of Chemistry and Chemical Engineering Central South University Changsha Hunan 410083 P. R. China