Mechanochemical Reactivity of a 1,2,4-Triazoline-3,5-dione-Anthracene Diels-Alder Adduct

Hao-Chun Chang; Min-Chieh Liang; Van-Sieu Luc; Chelsea Davis; Chia-Chih Chang

doi:10.1002/asia.202300850

Mechanochemical Reactivity of a 1,2,4-Triazoline-3,5-dione-Anthracene Diels-Alder Adduct

Chem Asian J. 2024 Jan 2;19(1):e202300850. doi: 10.1002/asia.202300850. Epub 2023 Nov 24.

Authors

Hao-Chun Chang^{1

2}, Min-Chieh Liang^{1

2}, Van-Sieu Luc^{1

3

4}, Chelsea Davis⁵, Chia-Chih Chang^{1

2}

Affiliations

¹ Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, No. 1001, Daxue Rd. East Dist., Hsinchu City, 300093, Taiwan.
² Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan.
³ Sustainable Chemical Science and Technology (SCST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei, 11529, Taiwan.
⁴ Institute of Chemistry, Academia Sinica, Taipei, 11529, Taiwan.
⁵ Department of Mechanical Engineering, University of Delaware, Newark, Delaware, 19716, U.S.A.

PMID: 37938167
DOI: 10.1002/asia.202300850

Abstract

Force-responsive molecules that produce fluorescent moieties under stress provide a means for stress-sensing and material damage assessment. In this work, we report a mechanophore based on Diels-Alder adduct TAD-An of 4,4'-(4,4'-diphenylmethylene)-bis-(1,2,4-triazoline-3,5-dione) and initiator-substituted anthracene that can undergo retro-Diels-Alder (rDA) reaction by pulsed ultrasonication and compressive activation in bulk materials. The influence of having C-N versus C-C bonds at the sites of bond scission is elucidated by comparing the relative mechanical strength of TAD-An to another Diels-Alder adduct MAL-An obtained from maleimide and anthracene. The susceptibility to undergo rDa reaction correlates well with bond energy, such that C-N bond containing TAD-An degrades faster C-C bond containing MAL-An because C-N bond is weaker than C-C bond. Specifically, the results from polymer degradation kinetics under pulsed ultrasonication shows that polymer containing TAD-An has a rate constant of 1.59×10^-5 min^-1 , while MAL-An (C-C bond) has a rate constant of 1.40×10^-5 min^-1 . Incorporation of TAD-An in a crosslinked polymer network demonstrates the feasibility to utilize TAD-An as an alternative force-responsive probe to visualize mechanical damage where fluorescence can be "turned-on" due to force-accelerated retro-Diels-Alder reaction.

Keywords: 1,2,4-triazoline-3,5-dione; polymer mechanochemistry; retro-Diels-Alder reaction; stress-sensing.

Abstract

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