Femtosecond 2D-IR spectroscopy has been used to study the structure of a [2]rotaxane composed of a benzylic amide macrocycle that is mechanically interlocked onto a succinamide-based thread. Both the macrocycle and the thread contain carbonyl groups, and by determining the coupling between the stretching modes of these groups from the cross-peaks in the 2D-IR spectrum, the structure of the macrocycle-thread system has been probed. Our results demonstrate that 2D-IR spectroscopy can be used to observe structural changes in molecular devices on a picosecond time scale.


Larsen, O. F. A., Bodis, P., Buma, W. J., Hannam, J. S., Leigh, D. A., & Woutersen, S. (2005). Probing the structure of a rotaxane with two-dimensional infrared spectroscopy. PNAS, 102, 13378–13382. doi:10.1073/pnas.0505313102