1. Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
2. Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321, Egypt
3. School of Chemistry, University of St Andrews, Andrews KY16 9ST, UK
4. Department of Chemistry, Khalifa University, Abu Dhabi 999041, United Arab Emirates