Synthesis and characterization of oxadisilole-fused 1H-benzo[f]indazoles and 1H-naphtho[2,3-f]indazoles

Oxadisilole-fused 1H-benzo[f]- and 1H-naphtho[2,3-f]indazoles have been synthesized by the 1,3-dipolar cycloaddition reactions of benzo- or naphtho-oxabicycloalkenes with nitrile imines generated in situ from N-arylhydrazonoyl chlorides followed by deoxygenation and aromatization. The photophysical, redox and thermal properties of these compounds have been characterized. Some of the indazoles show potential as deep-blue emitters for OLED applications as a result of their high fluorescence quantum yields and good thermal stabilities. Oxadisilole-fused 1H-benzo[f]- and 1H-naphtho[2,3-f] indazoles have been synthesized by the 1,3-dipolar cycloaddition of benzo- or naphtho-oxabicycloalkenes with nitrile imines followed by deoxygenation and aromatization. Their photophysical, redox and thermal properties show that some of the indazoles show potential as deep-blue emitters for OLED applications.