Synthesis, optical, and electrochemical properties, and theoretical calculations of BODIPY containing triphenylamine

Abstract

© 2016 Wiley Periodicals, Inc. The boron dipyrromethene (BODIPY) triads consisting of two triphenylamine units as electron donor (D) and BODIPY core as electron acceptor (A; B3, and B4) have been synthesized using facile palladium cross-coupling reactions to broaden the absorption of the BODIPY dyes. All dyes and intermediates were characterized by 1H NMR, 11B NMR, 13C NMR, and 19F NMR spectroscopies, UV–Vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and time-dependent density functional theory calculations. It was found that an increase in conjugation to the BODIPY core systematically extended the absorption and emission wavelength maxima. As a consequence, B4 containing the D–π–A–π–D structure, exhibited the longest absorption and emission maxima at 597 and 700 nm, respectively, with 1.8 eV in optical bandgap. The 96 nm red-shifted absorption of B4 as compared to the unsubstituted BODIPY (B1) indicated the effective electronic communication between triphenylamine and BODIPY. This suggested that the proper alignment of triphenylamine and BODIPY triad could lead to broader absorption and suitable low energy bandgap. Furthermore, the molecular modeling has been employed to analyze the electronic and optical properties of the dyes. We found that the optical, electrochemical, and theoretical bandgaps of all dyes were in good agreement.