Borylated Arylamine–Benzothiadiazole Donor–Acceptor Materials as Low-LUMO, Low-Band-Gap Chromophores

Fused and ladder-type benzothiadiazole–arylamine donor–acceptor C,N-chelated boron complexes were synthesized through direct electrophilic C–H borylation. The frontier molecular orbital energy levels of the borylated materials then could be modulated through variation of the exocyclic boron substituents by transmetalation with different diarylzinc reagents. The borylated materials possessed low band gaps and low LUMO energy levels with a number of examples also showing significant absorbance at >700 nm; however, low photoluminescence quantum yields were found for all these borylated compounds.