Naphthalene-fused BODIPY with large Stokes shift as saturated-red fluorescent dye for living cell imaging

A new fluorescent dye of 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) was prepared by fusing naphthalene unit to the zig-zag edge of BODIPY core by oxidization with iron (III) chloride. The naphthalene-fused BODIPY exhibits significant bathochromic shifts in both absorption and fluorescence spectrum compared with the non-fused BODIPY. In addition, the dye emits strong saturated-red fluorescence with a quantum yield of 55% and an enlarged Stokes of 56 nm in CHCl3 due to the formation of dimers and the desymmetrization of the molecule, which can be used to image living cells by fluorescence microscopy. Cell imaging experiments demonstrated its potential application as a probe in bio-organisms due to its excellent imaging effect and large Stokes shift. (C) 2015 Elsevier Ltd. All rights reserved.