Dynamic Covalent Spiropyran Exchange for Rapid Structural Diversification

Angewandte Chemie International Edition, vol. 64, pp. e202419531

Abstract

Here we disclose that spiropyrans are able to undergo dynamic covalent exchange via their corresponding merocyanine isomers. In the latter, the indolinium moieties can be exchanged by a Michael-type addition-elimination sequence, in which a methylene indoline attacks a merocyanine and subsequently the initial indoline fragment is cleaved. The rate and position of the exchange equilibrium strongly depend on the reaction conditions as well as the substitution pattern on the methylene indoline fragments. Importantly, spiropyran cross exchange is catalyzed by indolinium salts and provides the opportunity for rapid in situ structural diversification of spiropyrans. This was used as synthetic tool to access various, hitherto inaccessible spiropyrans as potential dual-color photoinitiators for xolography. Moreover, we foresee application to screen dynamic covalent libraries of spiropyrans for photochromic properties and to exploit their light-sensitivity to bias the thermal equilibrium.

Authors 3

1. Alwin Drichel Aachen Institute of Technical and Macromolecular Chemistry DWI-Leibniz-Institut für Interaktive Materialien: DWI-Leibniz-Institut fur Interaktive Materialien AG Hecht GERMANY

   RWTH Aachen University · DWI – Leibniz Institute for Interactive Materials

   Affiliation as printed

   DWI-Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52074 Aachen Germany

   Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 1 52074 Aachen Germany

   DWI-Leibniz-Institut für Interaktive Materialien: DWI-Leibniz-Institut fur Interaktive Materialien AG Hecht GERMANY

2. Yves Garmshausen
   Affiliation as printed

   xolo GmbH Volmerstraße 9B 12489 Berlin Germany

   xolo GmbH R&D GERMANY

3. Stefan Hecht corresponding Aachen Institute of Technical and Macromolecular Chemistry

   RWTH Aachen University · DWI – Leibniz Institute for Interactive Materials · Humboldt-Universität zu Berlin

   Affiliation as printed

   Center for the Science of Materials Berlin Humboldt-Universität zu Berlin Zum Großen Windkanal 2 12489 Berlin Germany

   DWI-Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52074 Aachen Germany

   Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Str. 2 12489 Berlin Germany

   Institute of Technical and Macromolecular Chemistry RWTH Aachen University Worringerweg 1 52074 Aachen Germany

   Humboldt-Universität zu Berlin Department of Chemistry, Laboratory of Organic Chemistry and Functional Materials Brook-Taylor-Str. 2 12489 Berlin GERMANY