1. State Key Laboratory of Luminescent Materials and Devices Institute of Polymer Optoelectronic Materials and Devices South China University of Technology Guangzhou 510640 P. R. China
2. Molecular Materials and Nanosystems Institute for, Complex Molecular Systems Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
3. Present address: Department of Organic Chemistry University of Murcia 30100 Murcia Spain