Opto-electrochemistry of pyridopyrazino[2,3-b]indole Derivatives

Here, pyridopyrazino[2,3-b]indole based D–A assembly was designed and synthesized with modulation of various electron-donating/withdrawing substituent and characterized by various spectroscopic methods. Pyridopyrazino[2,3-b]indole derivatives show inbuilt intramolecular charge transfer (ICT) transition which established D–A building in molecules and induces blue-green emission in the solution state. However, solid-state emission characteristics explore the emission property of some molecules towards aggregation-induced emission (AIE) effect which leads to the formation of emissive nano aggregates in THF/H₂O mixture. Alteration of substituent on pyridopyrazino[2,3-b]indole segment effectively tune electrochemical property and resulting LUMO energy level was found to be comparable with reported electron transporting/n-type materials. These properties and good thermal stability indicate that molecules have the potential to be used as solid-state emitter and n-type materials in optoelectronic devices.

Graphical Abstract

: Pyridopyrazino[2,3-b]indole derivatives possess inbuilt intramolecular charge-transfer to reveal donor-acceptor assembly within a molecule. Opto-electrochemical properties of it greatly influenced by an inductive and mesomeric effect caused by a substituted group. Strong solid-state emission owned by some molecule display AIE phenomenon. Additionally, LUMO value of derivatives exhibits electron-transporting ability hence could be used in organic electronics.