1. Department of Chemistry; Quaid-i-Azam University; Islamabad 45320 Pakistan
2. Department of Materials Science and Engineering; Iowa State University; Ames Iowa 50011 USA
3. University of Peshawar; Institute of Chemical Sciences; Peshawar 25120 Pakistan
4. Laboratory of Advanced Polymer Materials, Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 PR China
5. Department of Chemistry; University of Malaya; Lembah Pentai Kuala Lumpur 50603 Malaysia