Thieno[3,2-b]thiophene-based bridged BODIPY dimers: synthesis, electrochemistry, and one- and two-photon photophysical properties

Abstract

Four BODIPY dyes (6a–6d) with electron-donating or electron-withdrawing groups at the meso-position were synthesized by the Sonogashira coupling reaction of 2,5-diethynylthieno[3,2-b]thiophene with mono-iodo-BODIPY moieties. All compounds were fully characterized by ¹H NMR and MALDI-TOF MS. Their photophysical and electrochemical properties were studied by UV-visible absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, two-photon excitation spectroscopy and cyclic voltammetry. These conjugated dyes exhibit interesting photophysical properties such as a high molar extinction coefficient, large Stokes shift and high two-photon absorption cross section σ₂.