International Summer School PROGRAM - Laboratoire d'Infochimie ...

Towards a Light Driven Proton Pump
Britta Hesseler,
Melanie Zindler, Ulrich Lüning*
Otto-Diels-Institut für Organische Chemie, Olshausenstr. 40, 24098 Kiel, GER
bhesseler@oc.uni-kiel.de, luening@oc.uni-kiel.de
Light driven uphill transport of protons is an essential process in nature. In the
photosynthetic apparatus, light energy is used to pump protons across a cell membrane.
Scheme 1 depicts our model system. The proton transfer is realized by a photoswitchable
acid, like 2-(2,4-dinitrobenzyl)pyridine (DNBP), attached to a rotaxane.
Scheme 1: Uphill proton transfer by a rotaxane. Due to electrostatic repulsion the macrocycle moves
along the axle.
Upon irradiation, the photo-switchable acid tautomerizes to a more acidic form and
switches back in a thermal reaction (scheme 2).
Scheme 2: Tautomers of DNBP with different acidity.
Several novel DNBP derivatives were successfully synthesized and for this, a new
method to obtain di- and trinitrobenzyl substituted pyridine derivatives was
developed. [1] Furthermore several axles and macrocycles [2]
were synthesized to build a
[2]rotaxane via a slipping process.
R
R
R
I
H
N
N
O
Scheme 3: Synthesized axles and macrocycles for the rotaxane formation.
O
O
R
R
R = H, t-butyl
[1] A. Frey, C. Goeschen, C. Näther, U. Lüning, R. Herges, J. Phys. Org. Chem. 2010, 23, 1093-1098.
[2] U. Lüning, E. Mak, M. Zindler, B. Hartkopf, R. Herges, Eur. J. Org. Chem. 2010, 4932-4940.
R
‚
R
O
N
27
-
39
O
O O
R‘= H, OMe