Pure Appl. Chem., 2006, Vol. 78, No. 12, pp. 2247-2259
doi:10.1351/pac200678122247
On the way to supramolecular photochemistry at the single-molecule level*
Christian Schäfer1, Björn Decker1, Matthias Letzel1, Francesca Novara1, Rainer Eckel2, Robert Ros2, Dario Anselmetti2, and Jochen Mattay1
1Organic Chemistry I, Department of Chemistry, University of Bielefeld,P.O. Box 100131, 33501 Bielefeld, Germany; 2Applied Biophysics, Department of Physics, University of Bielefeld, P.O. Box 100131, 33501 Bielefeld, Germany
Abstract:
Two examples of artificial supramolecular host-guest systems derived from resorc[4]arenes (calix[n]arenes based on resorcinol) and ammonium ions as guests have been studied by atomic force microscopy (AFM). For the first time, real single-molecule events have been determined for this type of supramolecular complexes and off-rates as well as molecular parameters of single-molecule aggregates such as the depths of the binding pocket (molecular length parameter) could be measured by applying the methods of dynamic force spectroscopy. In addition, this technique was also applied to differentiate between the two states (open and closed) of a photoswitchable resorc[4]arene-anthracene tweezer. An investigation of the exchange rates of various complexes in the gas phase by means of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry confirmed the results of the AFM study.
Keywords: atomic force microscopy; mass spectrometry; photoswitches; resorc[4]arenes; single-molecule processes.
*Paper based on a presentation at the XXIst Symposium on Photochemistry, 2-7 April 2006, Kyoto, Japan. Other presentations are published in this issue, pp. 2193-2359.
All articles from the XXIst Symposium on Photochemistry, Kyoto, Japan, 2–7 April 2006.