1. Contribution from the Johann Wolfgang Goethe-Universität Frankfurt/M., Institut für Physikalische und Theoretische Chemie, Marie-Curie-Str. 11, D-60439 Frankfurt/M., Germany, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and National Creative Research Initiative Center for Superfunctional Materials, Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Pohang 790-784, Korea