Bioinspired Luminescent Europium-Based Probe Capable of Discrimination between Ag⁺ and Cu⁺

Due to their similar coordination properties, discrimination of Cu+ and Ag+ by water-soluble luminescent probes is challenging. We have synthesized LCC4Eu, an 18 amino acid cyclic peptide bearing a europium complex, which able bind one or ion the side chains two methionines, histidine 3-(1-naphthyl)-l-alanine. In this system, naphthyl moiety establishes cation−π interaction with these cations. It also acts as antenna for sensitization Eu3+ luminescence. Interestingly, when excited at 280 nm, LCC4Eu behaves turn-on probe (+150% Eu emission) turn-off (−50% emission). Shifting excitation wavelength 305 nm makes responsive (+380% but not other physiological Thus, uniquely capable discriminating from Cu+. A detailed spectroscopic characterization based on steady-state time-resolved measurements clearly demonstrates that relies electronic energy transfer naphthalene triplet state states lowers 700 2400 cm–1 Cu+, respectively. Spectroscopic data point modulation efficiency caused differential red shift triplet, deciphering luminescence response toward