A triarylboron-based binuclear Zn(II) complex as a two-photon fluorescent probe for simultaneous multicolor imaging of the cell membrane, endoplasmic reticulum, and nucleolus.

The visualization of subcellular structures is critical for understanding their intracellular function. We prepared two triarylboron-based multinuclear Zn2+ complexes, TAB-1-3Zn2+ and TAB-2-2Zn2+, which can be used as fluorescent probes for nucleoside polyphosphate (NPP) and RNA because their multi Zn2+ center can selectively combine with the phosphate side chain of NPP or RNA, accompanied by a corresponding fluorescence change. Among them, TAB-2-2Zn2+ is more suitable than TAB-1-3Zn2+ for live cell imaging because of its excellent cell membrane permeability resulting from amphiphilicity. Since the various membrane structures in cells are also composed of phosphoric acid bilayers, TAB-2-2Zn2+ may also be used to image various membrane structures. Various colocalization experiments further confirmed that TAB-2-2Zn2+ can achieve clear simultaneous imaging of the cell membrane, the endoplasmic reticulum, and the nucleolus. Graphical abstract.