Transition-Metal-Free Cascade C–N Bond Formation: An Effective Strategy for the Synthesis of β-Carboline N-Fused Imidazolium Acetates and Estimation of their Light-Emitting Properties

Abstract A simple, efficient, and practical metal-free protocol has been devised to synthesize imidazopyrido[3,4-b]indole-based fluorophores decorated with carbazole/β-carboline/pyridine scaffolds via three consecutive C–N bond formations in a single operation. A wide range of aromatic amines (2-aminopyridines, 3-aminocarbazole, and anilines) were successfully applied to synthesize the complex imidazolium ions. The significant features of this strategy include high efficiency, mild and environmentally benign reaction conditions, no chromatographic purification, and broad substrate scope with excellent yields of the isolated products. Moreover, excellent photophysical properties (ΦF up to 85%) were exhibited by these fluorophores.