1. Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry and Materials Science Northwest University Xi'an 710069 P. R. China
2. Shanghai Synchrotron Radiation Facility of Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201204 P. R. China
3. Department of Gastroenterology the First Affiliated Hospital of Xi'an Jiaotong University Xi'an 710061 P. R. China
4. State Key Laboratory of Luminescent Materials and Devices South China University of Technology Guangzhou 510640 P. R. China
5. Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates South China University of Technology Guangzhou 510640 P. R. China