I recently solved a crystal structure of a drug exporter bound to methylviologen (paraquat). When I was placing the substrate into the binding pocket, I realized that the two phenyl rings can rotate relative to each other, whereas I was expecting to see a planar molecule. Does anyone know how to find out whether methylviologen (paraquat) is a planar substrate or not?
Dear Ali Kermani in salts of methylviologen the central 4,4'-bipyridine unit is normally absolutely planar. For a typical example, please have a look at the following useful article in which the crystal structure of a methylviologen salt is described (paraquat is the corresponding dichloride salt):
Crystal Structure of 1,1′-dimethyl-[4,4′-bipyridine]-1,1′-diium tetrachloridozincate(II), C12H14Cl4N2Zn
Article Crystal Structure of 1,1′-dimethyl-[4,4′-bipyridine]-1,1′-di...
Fortunately this paper has been posted as public full text on RG, so that you can freely download it as pdf file.
However, the central bond between the two pyridyl rings is a single bond which allows for free rotation. Thus, depending on the steric requirements (e.g. in a binding pocket) it may well happen that the two rings are in a skewed or even perpendicular arrangement.
Good luck with your research!
- Badges
- Science topic
- Similar topics
- Engineering
- Petroleum Engineering
- Oil