Synthesis, spectroscopic characterization, one and two-photon absorption properties of β-β linked BODIPY dimers

Abstract

Five β-β linked BODIPY dimers (d1-d5) with different electron-donating/withdrawing groups at the meso-position were synthesized through improved synthetic methods. All compounds were characterized by 1H and 13C NMR and HRMS. The single crystal X-ray analyses indicate that d4 and d5 display a linear coplanar conformation with two linked BODIPY moiety. Their photophysical and electrochemical properties have been investigated by UV–vis absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, two-photon excited spectroscopy and cyclic voltammetry. The β-β linked BODIPY dimers exhibit a prominent red shift from the visible region to the red/near-infrared region of their absorption and emission spectra, large Stokes shifts and moderate two-photon absorption cross section σ2 with different groups at the meso-position.