Exploring tunable optical and electrochemical properties of donor–π–acceptor imidazole derivatives for organic electronics

Organic materials with tunable photophysical properties are vital for advanced light-emitting and charge-transport technologies. However, designing molecules that combine strong fluorescence with high thermal stability remains a significant challenge. This study presents the synthesis of four novel imidazole-based donor–π–acceptor (D–π–A) small molecules, IM3OMe , IM3Me , IM3F , and IM4F , tailored for organic electronic applications. A five-step synthetic route, incorporating isocyanide chemistry and Suzuki–Miyaura coupling, enabled selective substitution at the imidazole 5-position and the attachment of a carbazole donor unit. Structural characterization was performed using NMR, FTIR, and high-resolution mass spectrometry. The compounds exhibited solvent-dependent absorption and violet fluorescence, with large Stokes shifts (120–125 nm in EtOAc; 146–147 nm in DMSO). Fluorinated derivatives demonstrated enhanced fluorescence in low-polarity solvents. Electrochemical analysis revealed reversible redox behavior and tunable charge transport properties. Notably, IM3OMe displayed the smallest bandgap (0.844 eV), while fluorinated analogues exhibited lower charge-transfer resistance and longer electron lifetimes. Thermal analysis indicated that electron-donating substituents reduced thermal stability, whereas fluorinated derivatives enhanced it, with IM4F showing the highest thermal robustness. The data presented in this study provide valuable insights into the structure-property relationships of these newly explored imidazole-based D–π–A systems.