1. Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
2. Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany
3. Department of Chemistry, King Fahd University of Petroleum and Minerals, P.O. Box 5048, Dhahran 31261, Kingdom of Saudi Arabia