1. Department of General and Organic Chemistry, Faculty of Applied Sciences, Free University of Brussels V.U.B., Pleinlaan 2, Brussels B-1050, Belgium
2. Department of Chemistry, Northwest University, ShaanXi, Xian 710 069, China
3. High Resolution NMR Centre, Free University of Brussels V.U.B., Pleinlaan 2, Brussels B-1050, Belgium