Unlocking Structurally Nontraditional Naphthyridine-Based Electron-Transporting Materials with C–H Activation–Annulation

The inherent benefits of C–H activation have given rise to innovative approaches in designing organic optoelectronic molecules that depart from conventional methods. While theoretical calculations have suggested the suitability of the 2,6-naphthyridine scaffold for electron transport materials (ETMs) in organic light-emitting diodes (OLEDs), the existing synthetic methodologies have proven to be insufficient for the construction of multiple arylated and fully aryl-substituted molecules. Herein, we present a solution for the synthesis of 2,6-naphthyridine derivatives, with the rhodium-catalyzed consecutive C–H activation–annulation process of fumaric acid with alkynes standing as the pivotal step within this strategy. The ETMs, purposefully designed and synthesized based on the 2,6-naphthyridine framework, exhibit an impressively high glass-transition temperature (T_g) of 282 °C and high electron mobility (μ_e), setting a new benchmark for ETMs in OLEDs with a μ_e exceeding 10^–2 cm² V^–1 s^–1. These materials prove to be versatile ETM candidates suitable for red, green, and blue phosphorescent OLED devices.