An experimental and theoretical study of dimethylaminostyryl BODIPY-perylenetetracarboxylic derivative dyads: synthesis, properties and DFT calculation

Abstract

Dimethylaminostyryl BODIPY-perylene tetracarboxylic derivative (PTAC and PBI) dyads, OMePTAC-BODIPY, PTAC-BODIPY and PBI-BODIPY, were synthesized and investigated by spectral and DFT methods. UV-Vis absorption spectra revealed that the absorption coefficients in the region from 350 nm to 600 nm were distinctly enhanced by incorporation of perylene tetracarboxylic derivatives into the BODIPY block. Due to the photo-induced electron transfer effect, the fluorescence of the dyads was strongly quenched. Differential pulse voltammograms (DPV) were involved to evaluate the energy levels of the dyads. The oxidation peaks are almost exactly the same located at 0.53 eV vs. Ag/AgCl, and the reduction peaks occurred at −1.1 eV, −1.0 eV and −0.5 eV, shifted toward positive potential values, for OMePTAC-BODIPY, PTAC-BODIPY and PBI-BODIPY respectively, indicating that the LUMO levels of dimethylaminostyryl BODIPY-perylene tetracarboxylic derivatives dyads are precisely designed by variating acceptor units from BODIPYs meso-position. Singlet oxygen (¹O₂) experiments uncovered that ¹O₂ is much impeded along with the increase of the electron affinity of the electron acceptor units. The rates for the charge separation (k_CS) and charge recombination (k_CR) were deduced by the Marcus equation, for OMePTAC-BODIPY and PTAC-BODIPY, the k_CS (10¹¹ s⁻¹) are approximately three orders of magnitude faster than k_CR (10⁸ s⁻¹), which will be beneficial to the photoelectric conversion and energy storage process.