1. Beijing Key Laboratory of Photoelectronic/, Electrophotonic Conversion Materials; School of Chemistry and Chemical Engineering; Beijing Institute of Technology; Beijing 100081 P. R. China
2. Department of Chemistry; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
3. Department of Physical and Environmental Science; University of Toronto Scarborough; 1265 Military Trail Toronto Ontario M1C 1A4 Canada
4. Department of Chemistry; Oakland University; 2200 North Squirrel Road Rochester Michigan 48309 USA