Synthesis, Structures and Photophysical Properties of Asymmetric Fulvene-[b]-fused BODIPYs

Herein, we developed a one-pot procedure to synthesize novel fulvene-[b]-fused BODIPYs from alpha-(2-alkynylphenyl)-pyrrole and acylpyrrole, using 5-exo cyclization as the key transformation. Compared to benzene-[b]-fused BODIPYs, although they have similar chemical compositions, their structures and properties significantly differ from each other, which can be attributed to the less aromaticity of the fulvene linker than benzene. Notably, fulvene-[b]-fused BODIPY 1 b exhibits helical-twisted core skeleton, intensified red-shifted absorption, and peak fluorescence. In addition, the pathway of this one-pot reaction and the mechanism of POCl3 mediated 5-exo cyclization have been proposed by a combining experimental and computational study. In this work, we reported the one-pot synthesis, structures, and properties of novel fulvene-[b]-fused BODIPYs, in comparison with benzene-[b]-fused BODIPYs. The different structures and properties can be attributed to the less aromaticity of the fulvene linker than benzene. A new BODIPY with helical-twisted core skeleton and intensified red-shifted absorption was developed.+image