I made it with <a href="https://en.wikipedia.org/wiki/ChemTool" class="extiw" title="wikipedia:ChemTool">ChemTool</a> and <a href="https://en.wikipedia.org/wiki/Inkscape" class="extiw" title="wikipedia:Inkscape">Inkscape</a>.
<a href="//commons.wikimedia.org/w/index.php?title=User:Isilanes&amp;action=edit&amp;redlink=1" class="new" title="User:Isilanes (page does not exist)">Isilanes</a>
2007-05-12
<span class="int-own-work" lang="en">Own work</span>