1,4-Diaryl-7,10-dimethoxyquinoxalino[2,3-b]quinoxalines and Their Dihydro Derivatives: Redox Switching of NIR Absorption and Fluorescence

Due to the high-lying HOMO of the substituents and the low-lying LUMO inherited by the heterocyclic skeleton, the title quinoxalinoquinoxalines 1 exhibit absorption bands which extend to the NIR region, whereas the dihydro derivatives 2 are less colored but emit strong green fluorescence. Thus, the present pairs can serve as novel redox dyes for drastic spectral changes.