Theoretical Framework for Predicting Dynamic Covalent Exchange Based on Proton Affinities and Proton-Transfer...

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Chemistry

Background:

• Acylsemicarbazides (ASC) are dynamic covalent motifs enabling tunable polymer networks.
• ASC-based systems offer a balance of mechanical robustness, reprocessability, and stability.
• Understanding ASC bond exchange kinetics is crucial for designing advanced materials.

Purpose of the Study:

• To establish design principles for predicting acylsemicarbazide bond exchange kinetics.
• To elucidate factors influencing the rate of ASC bond dissociation.
• To guide the rational design of dynamic covalent networks.

Main Methods:

• Density functional theory calculations.
• Detailed kinetic studies of ASC dissociation mechanisms.
• Experimental measurement of ASC compound dissociation rates.

Main Results:

• Dissociation rates correlate with the proton affinity of the N-H bond adjacent to R2.
• Proton-transfer assistance is essential for efficient bond exchange.
• Water, neighboring ASCs, and hydrazides significantly lower the activation barrier for dissociation.

Conclusions:

• Proton affinity serves as a predictive tool for ASC dissociation rates.
• Autocatalysis via proton transfer is a key mechanism in ASC polymeric networks.
• Findings facilitate the rational design of reversible polymers and dynamic covalent networks.