1. School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, U.K., Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Campus Cantoblanco, 28049 Madrid, Spain, Department of Chemical Engineering, Chungbuk National University, Chungbuk 361-763, Korea, and Division of Chemical Engineering, Hanbat National University, Taejon 305-719, Korea