1. Department of Chemistry, Faculty of Sciences, Zanjan University 45195-313, Zanjan, I.R. Iran
2. Fakultät für Chemie und Pharmazie, Ludwig-Maximilians-Universität München, Butenandtstraße 5 – 13, Haus D, D-81377 München, Germany
3. NUI Galway, School of Chemistry, Galway, Ireland