Deep-blue thermally activated delayed fluorescence of a CF3-substituted carbene–metal–amide complex

Abstract

A gold-based carbene–metal–amides (CMA) complex, BICAuBGCF3, with a 2-(trifluoromethyl)-benzoguanidine amide (L) ligand was prepared in good yields and characterized. The CF₃-substituted amide donor ligand resulted in a 0.27 eV stabilization of the highest occupied molecular orbital (HOMO) and a wide energy gap of 2.97 eV. In fluid media, the complex experiences dynamic behavior between two isomeric forms, which reduces the blue luminescence quantum yield to 43%. In the solid state, the complex shows bright deep-blue thermally activated delayed fluorescence at 432 nm with 60% luminescence quantum yield owing to a small singlet triplet energy gap (ΔE_ST) down to 54 meV. Radiative rates (k_r) were calculated to be up to 1.4 × 10⁶ s⁻¹ in amorphous polystyrene media, demonstrating the BICAuBGCF3 complex as a p_romising material for optoelectronic applications.