T‐Shaped Benzimidazole Derivatives as Blue‐Emitting Materials: The Role of C2 Substituents on Photophysical Properties

Abstract

The synthesis, characterization and photophysical properties of as eries of T-shaped benzimidazole derivatives decorated with triphenylamine donors at positions C4 and C7 and variousa romatic units at C2 are reported. The absorption properties of the dyes are predominantly influenced by the electronic properties of the benzimidazole and triphenylamine units,w hereas the emission characteristics are determined by the nature of the aromatic segment at C2. All the compounds display blue emission with moderate quantum yields in solution and solid states. They displayed multiple quasi-reversible oxidations originating from the triphenylamine units, demonstrating the electronic communication between these moieties. In addition, they showed high thermal stabilityw ith decomposition onset temperatures greater than 384 8C. The excited-state lifetime of the dyes varied in the range 2.00-6.18 ns. Ap yrene-containing dye exhibited the longest lifetimei nt he series, attributable to the formation of excimers in the excited state.