Triphenylphosphine-bonded coumaranone dyes realize dual color imaging of mitochondria and nucleoli

A sort of new triphenylphosphine-bonded fluorescence probes have been prepared, which enable dual-color fluorescence imaging of mitochondria and nucleoli in living cells. [Display omitted] •3-Coumaranone offers excellent opportunities for fluorescence probe design.•The first example to use triphenylphosphonium (TPP)-bonded dyes for RNA imaging.•The proposed probes can discriminate mitochondria and nucleoli via dual-color emissions.•The morphological changes of nucleoli upon drug stress have been evaluated by the synthetic probes. Probing intracellular organelles with fluorescent dyes offers opportunities to understand the structures and functions of these cellular compartments, which is attracting increasing interests. Normally, the design principle varies for different organelle targets as they possess distinct structural and functional profiles against each other. Therefore, developing a probe with dual intracellular targets is of great challenge. In this work, a new sort of donor–π–bridge–acceptor (D-π-A) type coumaranone dyes (CMO-1/2/3/4) have been prepared. Four fluorescent probes (TPP@CMO-1/2/3/4) were then synthesized by linking these coumaranone dyes with an amphiphilic cation triphenylphosphonium (TPP). Interestingly, both TPP@CMO-1 and TPP@CMO-2 exhibited dual color emission upon targeting to two different organelles, respectively. The green emission is well localized in mitochondria, while, the red emission realizes nucleoli imaging. RNA is the target of TPP@CMOs, which was confirmed by spectroscopic analysis and computational calculation. More importantly, the number and morphology changes of nucleoli under drug stress have been successfully evaluated using TPP@CMO-1.