Paper in Angewandte Chemie

Radical-Pairing Interactions in a Molecular Switch Evidenced by Ion Mobility Spectrometry and Infrared Ion Spectroscopy



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Radical-Pairing Interactions in a Molecular Switch Evidenced by Ion Mobility Spectrometry and Infrared Ion Spectroscopy

 

 

Affiliations

  • 1 University of Liege: Universite de Liege, UR Molsys, BELGIUM.
  • 2 Radboud University: Radboud Universiteit, Felix Laboratory, NETHERLANDS.
  • 3 Northwestern University, Department of Chemistry, UNITED STATES.
  • 4 University of Liege: Universite de Liege, UR Molsys, Allee du Six Aout, 11 - Quartier Agora, 4000, Liege, BELGIUM.

Abstract

The digital revolution sets a milestone in the progressive miniaturization of working devices and in the underlying advent of molecular machines. Foldamers involving mechanically entangled components with modular secondary structures are among the most promising designs for molecular switch-based applications. Characterizing the nature and dynamics of their intramolecular network following the application of a stimulus is the key to their performance. Here, we use non-dissociative electron transfers as a reductive stimulus in the gas phase and probe the consecutive co-conformational transitions of a donor-acceptor oligorotaxane foldamer using electrospray mass spectrometry interfaced with ion mobility and infrared ion spectroscopy. The comparison of collision cross section distributions for analogous closed-shell and radical molecular ions sheds light on their respective formation energetics while variations in their respective infrared absorption bands evidence different intramolecular organizations as the foldamer gets compact. These differences are compatible with the advent of radical-pairing interactions.

Keywords: IR spectroscopy; Ion Mobility; Mass Spectrometry; donor-acceptor systems; supramolecular chemistry.

 

Link : DOI: 10.1002/anie.202014728

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