Photodissociation of B–N Lewis Adducts: A Partially Fused Trinaphthylborane with Dual Fluorescence

The synthesis of a planarized trinaphthylborane
with partially
fused structure is presented. This compound shows not only high chemical
and thermal stability but also sufficient Lewis acidity to form Lewis
adducts with pyridine derivatives in solution. The B–N Lewis
adducts exhibit unprecedented photodissociation behavior in the excited
state, reminiscent of the photogeneration of carbenium ions from triarylmethane
leuco dyes. Consequently, these B–N Lewis adducts exhibit dual
fluorescence emission arising from the initial tetracoordinate B–N
adducts and the photodissociated tricoordinate boranes.