Issue 22, 2023

Mechanochemical reactivity of a multimodal 2H-bis-naphthopyran mechanophore

Abstract

Multimodal mechanophores that react under mechanical force to produce discrete product states with uniquely coupled absorption properties are interesting targets for the design of force-sensing polymers. Herein, we investigate the reactivity of a 2H-bis-naphthopyran mechanophore that generates thermally persistent mono-merocyanine and bis-merocyanine products upon mechanical activation in solution using ultrasonication, distinct from the thermally reversible products generated photochemically. We demonstrate that a force-mediated ester C(O)–O bond scission reaction following ring opening establishes an intramolecular hydrogen bond, locking one merocyanine subunit in the open form. Model compound studies suggest that this locked subunit confers remarkable thermal stability to bis-merocyanine isomers possessing a trans exocyclic alkene on the other subunit, implicating the formation of an unusual trans merocyanine isomer as the product of mechanochemical activation. Density functional theory calculations unexpectedly predict a thermally reversible retro-cyclization reaction of the bis-merocyanine species that could explain the mechanochemical generation of the unusual trans merocyanine isomer.

Graphical abstract: Mechanochemical reactivity of a multimodal 2H-bis-naphthopyran mechanophore

Supplementary files

Article information

Article type
Paper
Submitted
29 မတ် 2023
Accepted
02 မေ 2023
First published
10 မေ 2023

Polym. Chem., 2023,14, 2717-2723

Author version available

Mechanochemical reactivity of a multimodal 2H-bis-naphthopyran mechanophore

S. K. Osler, M. E. McFadden, T. Zeng and M. J. Robb, Polym. Chem., 2023, 14, 2717 DOI: 10.1039/D3PY00344B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements