Solvent-free isomerization of trialkoxy-heptazine derivatives featuring efficient intermolecular rearrangements†

Graphitic carbon nitrides (GCNs) have garnered broad research interest due to their potential in various applications. This study reveals a unique characteristic of heptazine, a repeating structural unit of GCN. Trialkoxy-heptazine, Hz(OR)₃, undergoes nearly quantitative isomerization to trialkylheptazine-trione, HzTO-R₃, under solvent-free conditions. While most quantitative isomerizations proceed intramolecularly, this isomerization occurs through intermolecular rearrangement reactions. The isomerization introduces three carbonyl groups, drastically altering the physical properties of the parent molecules and making them ideal for stimuli-responsive materials. Since this isomerization proceeds efficiently under solvent-free conditions, it can potentially be integrated into GCN-based materials, offering significant promise for the development of novel GCN-based materials and their applications.