1. School of Pharmaceutical Science and Technology; Tianjin University; Tianjin 300072 P. R. China
2. Departamento de Química; Instituto Tecnológico de Aeronáutica; São José dos Campos 12228-900 São Paulo Brazil
3. Institute for Soil Research; University of Natural Resources and Life Sciences Vienna; Peter-Jordan-Strasse 82, A- 1190 Vienna Austria
4. Institute for Theoretical Chemistry; University of Vienna, A-; 1090 Vienna Austria