Infrared study of intercomponent interactions in a switchable hydrogen-bonded rotaxane

Jagesar, D.C., Hartl, F. ORCID: https://orcid.org/0000-0002-7013-5360, Buma, W.J. and Brouwer, A.M. (2008) Infrared study of intercomponent interactions in a switchable hydrogen-bonded rotaxane. Chemistry- A European Journal, 14 (6). pp. 1935-1946. ISSN 0947-6539 doi: 10.1002/chem.200701531

Abstract/Summary

The macrocycle in rotaxane 1 is preferentially hydrogen bonded to the succinamide station in the neutral form, but can be moved to the naphthalimide station by one-electron reduction of the latter. The hydrogen bonding between the amide NH groups of the macrocycle and the C=O groups in the binding stations in the thread was studied with IR spectroscopy in different solvents in both states. In addition, the solvent effect on the vibrational frequencies was analyzed; a correlation with the solvent acceptor number (AN) was observed. The conformational switching upon reduction could be detected by monitoring the hydrogen-bond-induced shifts of the v(CO) frequencies of the C=O groups of the succinamide and the reduced naphthalimide stations. The macrocycle was found to shield the encapsulated station from the solvent: wavenumbers of v(CO) bands of the C=O groups residing inside the macrocycle cavity remain unaffected by the solvent polarity.