1. Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong, P.R. China
2. Département de Chimie, Université de Sherbrooke, 2550 Boul. Université, Sherbrooke, PQ, J1K 2R1 Canada
3. Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
4. Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China