Modulation of ΔEST and room temperature phosphorescence in carbazole derivatives†
Abstract
A simple strategy to modulate the singlet–triplet energy gap in 3,6-diaryl-N-acetophenylcarbazole derivatives is developed. Different substituents significantly influenced ΔEST, which is correlated for the first time with the singlet–triplet state dipole moments. Phosphorescence at ambient conditions in powder form (τ is up to 248 μs) and ultra long lifetime (up to 2.2 s) at 77 K is observed.