Synthesis, Photophysical Properties, and Aromaticity of Pyrazine-Fused Tetrazapentalenes

Pyrazine-fused 1,2,6,6a-tetrazapentalenes (PyTeAP) are zwitterionic tricyclic compounds exhibiting an original pattern with four consecutive nitrogen atoms. They were obtained by a challenging cyclization through the formation of a N-N bond under thermolytic conditions. Ten derivatives were synthesized, and the original scaffold of PyTeAP was confirmed by single-crystal X-ray diffraction analysis of one derivative. Examination of their photophysical properties in solution revealed blue fluorescence with lambda em = 416-426 nm. Theoretical investigations of the aromaticity in these compounds through magnetic criteria evidenced the presence of a dominant 14-electron circuit at the periphery.

Automated summary

Pyrazine-fused 1,2,6,6a-tetrazapentalenes (PyTeAP) are zwitterionic tricyclic compounds with a unique pattern of four consecutive nitrogen atoms. Ten derivatives were successfully synthesized and the original scaffold of PyTeAP was confirmed through X-ray diffraction analysis. These compounds exhibited blue fluorescence in solution and theoretical investigations confirmed their aromaticity.