47243-AC4
New Multi-Redox Heterocycles for Materials Applications
Heterocyclic compounds with multi-redox properties are of interest for materials and biological applications. In this context, we have focused on two new heterocycles containing fused [1,2,4]triazine and [1,2,4,5]tetrazine rings as potential 1-electron redox systems. During the first year of the PRF funding, we have developed a practical method for the preparation of a fused ring triazinium cation (pyrido[1,2-c]benzo[d][1,2,4]triazinium). The formation of the cation is accomplished by photochemical cyclization under pH neutral conditions in MeCN or aqueous MeCN solutions, and the product is isolated in >75% yields. The developed method is, in principle, suitable for the preparation of functionalized derivatives, incorporation of the triazinium into more complex chemical structures, and tailoring the molecular and bulk properties of the material. Therefore, the work has recently been extended to the triazinium substituted with alkoxy and carboxy groups. We also investigate the formation of pyrido[1,2-c][1,2,4,5]tetrazine. Our preliminary results indicate that the desired heterocyclic skeleton is formed in a cyclization process albeit in low yields. Optimization of reaction conditions and search for alternative methods are currently being investigated.
