. 2009 Nov 25;14(12):4838–4848. doi: 10.3390/molecules14124838
© 2009 by the authors;
licensee Molecular Diversity Preservation International, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
Figure 4.
Bipolar structures.