Synthesis and Characterization of Polyacetyltetrazine from Hydrazonoyl via [3+3] Self-Polycycloaddition

Over the past decade, tetrazines have emerged as key molecules in metal complexation, anion binding, and molecular recognition. However, limited research has focused on combining tetrazine rings into the polymer backbones.

This research aimed to focus on synthesizing novel 1,2,4,5-polyacetyl-tetrazines through 1,3-dipolar self-cycloaddition. In this process, bis-α-keto-hydrazonoyl compounds, in the presence of a base, were rapidly converted into bisnitrilimine intermediates. These intermediates then underwent head-to-tail self-polymerization via 1,3-dipolar cycloaddition, resulting in the formation of poly(1,2,4,5-polyacetyltetrazines). The polymers were found to be soluble in various organic solvents, resistant to oxidative degradation, and thermally stable. Characterization of these compounds was performed using techniques, such as proton and carbon nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA).

In this study, polyacetyl-tetrazines were synthesized by employing a [3+3] selfcycloaddition mechanism, involving the reaction of hydrazonoyl compounds to form six-membered tetrazine rings within the polymer backbone.

The synthesis of new polyacetyltetrazines validated the effectiveness of this method. This method will be useful due to its low cost, mild reaction conditions, and the commercial availability of the chemicals. It could potentially offer a novel pathway for synthesizing tetrazine-based polymers with unique properties.