F. Du Prez

Design of a thermally controlled sequence of triazolinedione-based click and transclick reactions

H.A. Houck, K. De Bruycker, S. Billiet, B. Dhanis, H. Goossens, S. Catak, V. Van Speybroeck, J.M. Winne, F. Du Prez
Chemical Science
8 (4), 3098-3108


The reaction of triazolinediones (TADs) and indoles is of particular interest for polymer chemistry applications, as it is a very fast and irreversible additive-free process at room temperature, but can be turned into a dynamic covalent bond forming process at elevated temperatures, giving a reliable bond exchange or ‘transclick’ reaction. In this paper, we report an in-depth study aimed at controlling the TAD – indole reversible click reactions through rational design of modified indole reaction partners. This has resulted in the identification of a novel class of easily accessible indole derivatives that give dynamic TAD-adduct formation at significantly lower temperatures. We further demonstrate that these new substrates can be used to design a directed cascade of click reactions of a functionalized TAD moiety from an initial indole reaction partner to a second indole, and finally to an irreversible reaction partner. This controlled sequence of click and transclick reactions of a single TAD reagent between three different substrates has been demonstrated both on small molecule and macromolecular level, and the factors that control the reversibility profiles have been rationalized and guided by mechanistic considerations supported by theoretical calculations.

Open Access version available at UGent repository
Green Open Access

Triazolinediones enabling ultrafast and reversible click chemistry for facile design of healable and reshapable polymers

S. Billiet, K. De Bruycker, F. Driessen, H. Goossens, V. Van Speybroeck, J. Winne, F. Du Prez
Nature Chemistry
6 (9), 815-821


With its focus on synthetic reactions that are highly specific and reliable, ‘click’ chemistry has become a valuable tool for many scientific research areas and applications. Combining the modular, covalently bonded nature of click-chemistry linkages with an ability to reverse these linkages and reuse the constituent reactants in another click reaction, however, is a feature that is not found in most click reactions. Here we show that triazolinedione compounds can be used in click-chemistry applications. We present examples of simple and ultrafast macromolecular functionalization, polymer–polymer linking and polymer crosslinking under ambient conditions without the need for a catalyst. Moreover, when triazolinediones are combined with indole reaction partners, the reverse reaction can also be induced at elevated temperatures, and the triazolinedione reacted with a different reaction partner, reversibly or irreversibly dependent on its exact nature. We have used this ‘transclick’ reaction to introduce thermoreversible links into polyurethane and polymethacrylate materials, which allows dynamic polymer-network healing, reshaping and recycling.

Solvent Effects on Free Radical Polymerization Reactions: The Influence of Water on the Propagation Rate of Acrylamide and Methacrylamide

B. De Sterck, R. Vaneerdeweg, F. Du Prez, M. Waroquier, V. Van Speybroeck
43 (2), 827–836


The polymerization of acrylamide (AA) and methacrylamide (MAA) was studied by an extensive set of computational methods with a particular focus on the possible influence of water molecules on the propagation reaction. An extensive set of electronic structure methods was tested, consisting of B3LYP, BMK, MPWB1K, MP2, and B2-PLYP of which some include dispersion effects. The effect of water on the transition state is modeled in two different ways. Explicit water molecules are added to the system, showing that replacing the hydrogen bond that dominates the transition state structure by a water-mediated hydrogen bond, results in more stable, more feasible transition states. This effect is the largest for AA polymerization, a monomer that is known to experience a larger solvent effect than MAA. Additionally, a conductor-like polarizable continuum model (C-PCM) is applied on both the transition states in gas phase and the ones bearing explicit water molecules. This model has a dramatic effect on all the propagation rates, raising them by about 3 orders of magnitude. The inclusion of explicit water molecules gives insight into the role of water molecules and the formation of prereactive complexes. The relative rate of polymerization of AA with regard to MAA is well reproduced for a trimeric propagating radical with inclusion of explicit water molecules or by using an implicit solvation model at the BMK and MPWB1K level of theory.

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