1. Division of Organic Chemistry and Biochemistry Rudjer Bosković Institute P.O.B. 180 HR-10002 Zagreb Croatia
2. Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas 79409-1061 USA
3. Institute for Theoretical Chemistry University of Vienna Währingerstrasse 17 A-1090 Vienna Austria
4. School of Pharmaceutical Sciences and Technology Tianjin University Tianjin 300072 P.R.China