Nine nonplanar BOPYIN derivatives are prepared by two steps in one pot. The relationship between the BOPYIN structures and the optical properties is investigated systematically. The work illustrates that donating group modification on the pyrrole unit and π-enlargement on the indole unit may promote the red shift of photophysical spectra synergistically.
Borondifluoride-3,3-dimethyl-2-[2-(2-pyrrolyl) ethenyl] indole (BOPYIN), a seven-membered, nonplanar boron complex, features typical photophysical properties, such as relatively large Stokes shift. Herein, a series of BOPYINs are prepared by a two-step, one-flask synthesis. Based on the modification position, these derivatives could be divided into three sections, including withdrawing substituted dyes, dyes with donating substitution on the pyrrole unit, and dyes with further π-enlarged substitution on indole unit. The relationship between diverse modified structures and photophysical properties are systematically discussed by experiments and DFT calculations. This work illustrates that donating-group modifications on pyrrole and π-enlargement on the indole unit may promote the red shift of the photophysical spectra synergistically.Zum Volltext