1. Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
2. Institute of Soil Research, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria
3. School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P.R. China
4. Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A1090 Vienna, Austria