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Updated: Jan 26, 2026

Measuring Light-Switching Behavior Using an Occupancy and Light Data Logger
Published on: January 16, 2020
Light-Controlled Conformational Switch of an Aromatic Oligoamide Foldamer
Bappaditya Gole1, Brice Kauffmann2, Victor Maurizot1
1CBMN (UMR5248), Univ. Bordeaux - CNRS - IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France.
Abstract:
An aromatic oligoamide sequence composed of a light-responsive diazaanthracene-based aromatic β-sheet flanked by two variable diameter helical segments was prepared. Structural investigations revealed that such oligomers adopt two distinct conformations: a canonical symmetrical conformation with the two helices stacked above and below the sheet, and an unanticipated unsymmetrical conformation in which one helix has flipped to directly stack with the first helix. Photoirradiation of the foldamer led to the quantitative, and thermally reversible, formation of a single photoproduct resulting from the [4+4] cycloaddition of two diazaanthracenes within the aromatic β-sheet. NMR and crystallographic studies revealed a parallel arrangement of the diazaanthracene photoproduct and a complete conversion into a symmetrical conformation requiring a rearrangement of all unsymmetrical conformers. These results highlight the potential of foldamers, with structures more complex than isolated helices, for the design of photoswitches showing nontrivial nanometer scale shape changes.
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