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Join Dr Sarah Pike (School of Chemistry at Birmingham University) for a seminar on multi-stimuli-responsive foldamers. Also on Microsoft Teams

Foldamers are synthetic helical oligomers that adopt stable secondary conformations in solution reminiscent of the folding behaviour of some natural systems.1 These artificial systems are of great interest to chemists due to their wide-ranging applications in a diverse array of fields including supramolecular chemistry, crystal engineering, synthesis and materials chemistry.2 In recent years, there has been an explosion in reports of responsive foldamers that can demonstrate stimuli-controlled changes to their scaffold,3 but literature examples of multi-stimuli-responsive foldamers remain rare.4

Herein, we report on dual, light-responsive and redox-active foldamers that demonstrate reversible and robust stimuli-induced behaviour (Fig. 1a).5 UV/Vis, 1H NMR and circular dichroism (CD) spectroscopy and cyclic voltammetry have been used to establish the reversibility and robust nature of the light- and redox-driven behaviour of these new foldamers (Fig. 1b). Minimal levels of fatigue are observed for these systems even upon multiple cyclic treatments with irradiative/non-irradiative and oxidative/reductive conditions. This work paves the way towards the creation of stimuli-responsive foldamers of increasing sophistication capable of demonstrating reversible and robust responses to multiple distinct stimuli.

Figure 1. a) Dual, achiral light-responsive and redox-active foldamer; b) CD spectra of a related chiral dual-responsive foldamer before irradiation (blue line) and at the photo-stationary state (PSS) (dashed red line) after irradiation of a 6.1 × 10-5 M dichloromethane sample with 365 nm for 10 min. Grey lines show the thermal relaxation of a chiral dual-responsive observed over 80 min. Inset shows light- and thermally-driven cycles of E/Z-isomerisation of the azo bonds of a chiral dual-responsive foldamer.

References

[1] a) G. Guichard and I. Huc, Chem. Commun. 2011, 47, 5933; b) B. A. F. Le Bailly and J. Clayden, Chem. Commun. 2016, 52, 4852.

[2] C. M Goodman, S. Choi, S. Shandler and W. F DeGrado, Nat. Chem. Biol., 2007, 38, 252.

[3] Z. Hu and S. Hecht, Chem. Commun., 2016, 52, 6639.

[4] M. H.-Y. Chen, S. Y.-L. Leung and V. W.-W. Yam, J. Am. Chem. Soc., 2019, 141, 12312.

[5] A. R. Davis, J. O. Dismorr, L. Male, J. H. R. Tucker and S. J. Pike, Chem. Eur. J., 2024, e202402423.

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