Synthesis and properties of azulene-functionalized BODIPYs†
A series of azulene-functionalized BODIPY derivatives have been synthesized via a Suzuki–Miyaura cross-coupling reaction. The introduction of 2-azulenyl moieties onto the BODIPY core results in more red-shifted absorption bands than those observed for 1-azulenyl functionalization. Upon protonation by TFA, a blue shift of the main absorption band of the 2-azulenyl-substituted compounds is observed along with a decrease in intensity, and a new weaker peak is observed at long wavelength. In contrast, the absorption of the 1-azulenyl-substituted compounds is almost unchanged upon protonation.