1College
of Chemistry and Chemical Engineering, Southwest Petroleum University, No. 8 Xindu Road, Chengdu 610500, P. R. China
2Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
3School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798