1. Chemistry Department University College London 20 Gordon Street London WC1E 0AJ UK
2. Department of Chemistry Quaid-i-Azam University Islamabad 453208 Pakistan
3. Department of Chemistry Federal Urdu University of Arts, Sciences and Technology Karachi 75300 Pakistan
4. H.E.J. Research Institute of Chemistry International Center for Chemical and Biological Sciences University of Karachi Karachi 75270 Pakistan