1. Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States
2. Department
of Chemistry, Northeast Normal University, Changchun 130024, P. R. China
3. Department
of Chemistry, Shantou University, Guangdong 515063, P. R. China
4. School
of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, P. R. China