Controlling thermal reactivity with different colors
Hannes A. Houck
, Filip E. Du Prez
& Christopher Barner-Kowollik
The ability to switch between thermally and photochemically activated reaction channels with
an external stimulus constitutes a key frontier within the realm of chemical reaction control.
Here, we demonstrate that the reactivity of triazolinediones, powerful coupling agents in
biomedical and polymer research, can be effectively modulated by an external photonic ﬁeld.
Speciﬁcally, we show that their visible light-induced photopolymerization leads to a quanti-
tative photodeactivation, thereby providing a well-deﬁned off-switch of their thermal reac-
tivity. Based on this photodeactivation, we pioneer a reaction manifold using light as a gate to
switch between a UV-induced Diels–Alder reaction with photocaged dienes and a thermal
addition reaction with alkenes. Critically, the modulation of the reactivity by light is reversible
and the individually addressable reaction pathways can be repeatedly accessed. Our
approach thus enables a step change in photochemically controlled reactivity, not only in
small molecule ligations, yet importantly in controlled surface and photoresist design.
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George Street, Brisbane QLD 4000, Australia.
Macromolecular Architectures, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstraße 18, 76131
Institut für Biologische Grenzﬂächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-
Polymer Chemistry Research Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular
Chemistry, Ghent University, Krijgslaan 281 S4-bis, 9000 Gent, Belgium. Correspondence and requests for materials should be addressed to
F.E.D.P. (email: ﬁlip.firstname.lastname@example.org) or to C.B-K. (email: email@example.com)