1,3a,6a-Triazapentalene Systems: Towards Extended Planar Materials

Key words

nitrogen heterocycles - click chemistry - mechanochromism

Significance

Designing linearly bonded aromatic systems with a planar form introduces new materials with highly conductive properties for potential applications in molecular wires. A recently developed 1,3a,6a-triazapentalene (TAP) has been developed as a novel fluorescent chromophore with a 10π-electron system in a compact bicyclo[3.3.0]octane skeleton (highlighted core of 5). The dimer and trimer (8 and 10, respectively) were synthesized sequentially and characterized by a linear connection in planar form with alternating charges between the linked monomers.

 

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Comment

Tap units were synthesized by click reactions of alkynes (1) with azidotriflate (2), which could be extended by sequential reactions repeating the same procedure. The alternating charge led to unique fluorescence properties derived from changes in the aggregation state under concentrated conditions. Extension of the bonded systems also resulted in increased fluorescence in the solid state and fluorescence change upon mechanical grinding.

 

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