1. Fakultät für Chemie und Pharmazie, Universität Regensburg, 93040 Regensburg, Germany
2. GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
3. Chemistry Department, Faculty of Science, Benha University, 13518 Benha, Egypt
4. Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK