Asymmetric anthracene-fused BODIPY dye with large Stokes shift: Synthesis, photophysical properties and bioimaging

A new asymmetric fluorescent dye of the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) class was prepared by fusing an anthracene unit to the zig-zag edge of the BODIPY core by an FeCl3-mediated oxidative cyclodehydrogenation reaction and the photophysical properties of the new BODIPY analogue were investigated. The anthracene-fused BODIPY exhibits significant bathochromic shifts in both absorption and fluorescence maxima compared with a related non-fused BODIPY. In addition, the anthracene-fused BODIPY exhibited a small energy gap (1.81 eV), large Stokes shift and high photo stability. Especially, the emission of the dye extended into the deep red (similar to 640 nm) region. The extensive pi conjugation is responsible for the red-shifted emission. Moreover, the dye emits strong saturated, red fluorescence with a quantum yield of 40% and an enlarged Stokes shift of 1425 cm(-1) (53 nm) in CHCl3, which can be used to image living cells by fluorescence microscopy. Cell imaging experiments demonstrated its potential application as a probe in bioorganisms due to its excellent imaging contrast. (C) 2015 Elsevier Ltd. All rights reserved.