An Azide-Substituted Triarylborane: A Key Compound for the Facile Synthesis of Fluorescent Triarylboranes Bearing Triazole Moieties as Connectable π-Conjugated System Linkages

Tris(4-azido-2,6-dimethylphenyl)borane was readily synthesized from an amino-substituted triarylborane using tert-butyl nitrite and trimethylsilylazide. This compound can easily be converted into triarylboranes bearing various π-conjugated moieties with triazole ring π-linkers through a Huisgen cycloaddition. UV/Vis absorption spectra and DFT calculations suggested that constructing a triazole linker successfully extended the π-conjugated system of triarylboranes. Triarylboranes obtained using this method maintained their fluorescent nature. In particular, the triarylborane linking N,N-dimethylaminophenyl groups with triazole rings exhibited notable visible solvatofluorochromism and fluorescence color change upon addition of a fluoride anion.