Responsive luminescent probes emitting in the near-infrared (NIR) are in high demand today for biological applications as they allow for the easy and unambiguous discrimination of autofluorescence. Due to their luminescence properties, lanthanide ions offer an interesting alternative to classical organic fluorescent dyes. This has stimulated the development of lanthanide-based responsive probes. Nevertheless, responsive probes that can operate in water with NIR-emitting lanthanide ions are scarce. In this communication, zinc fingers are shown to be versatile scaffolds to elaborate a variety of Zn -responsive probes based on lanthanide emission and featuring desirable properties for the selective detection of Zn in experimental conditions close to cellular. Of special interest is a NIR-emitting probe relying on Nd emission.

The interest in ratiometric luminescentp robes that detecta nd quantify as pecific analyte is growing. Owing to their special luminescence properties, lanthanide(III) cationso ffer attractive opportunities for the design of dual-color ratiometric probes. Here, the design principle of hetero-bis-lanthanide peptidec onjugates by using native chemical ligation is described for perfect control of the localization of each lanthanide cation within the molecule. Two zinc-responsive probes, r-LZF1 Tb j Cs124 j Eu and r-LZF1 Eu j Cs124 j Tb are described on the basis of az inc finger peptide andt wo DOTA(DOTA = 1,4,7,10-tetraaza-cyclododecane-1,4,7,10-tetra-acetic acid) complexes of terbium and europium.B oth display dual-color ratiometric emission in response to the presence of Zn 2 + .B yu sing as creening approach, anthracene was identified for the sensitization of the luminescence of two near-infrared-emitting lanthanides, Yb 3 + and Nd 3 +. Thus, two novel zinc-responsive hetero-bis-lanthanide probes, r-LZF3 Yb j Anthra j Nd and r-LZF3 Nd j Anthra j Yb were assembled, the former offeringaneat ratiometric response to Zn 2 + with emission in the near-infrared around1 000 nm, which is unprecedented.