There are dozen molecular editor for chemistry and biology , but very few of them are open source (or even free for education), and the lasts are feature-limited. Thus, XDrawChem  can draw quiet complicated molecules, but draws them not very beautifully. In the other side, this open source program can export images in SVG format, used as default in Inkscape , a famous vector editor, which is used to produce very beautiful drawings.
Our action is:
First, draw the molecule (or parts of it) in XDrawChem, then export the image in SVG format:
|Draw part of the future molecule (Tinuvin 320) in XDrawChem|
Open and edit the SVG file in Inkscape, and don't forget to convert text to path, if you want to edit the file in other system:
|Tinuvin 320 (antioxidant)|
Finally, save as pdf to use in a LaTeX document, or export to PNG to use in OpenOffice.org.