Fluorescence intensity (λ_em = 483 nm) of compound 1-Cu²⁺ to various amino acids: the first bars represent the fluorescence intensity upon addition of 4 equivalents of various amino acids; the second bars represent the fluorescence intensity after subsequent addition of 2 equivalents of GSH to the non-sulfhydryl amino acids solution, respectively.

<p>Fluorescence intensity (λ_em = 483 nm) of compound 1-Cu²⁺ to various amino acids: the first bars represent the fluorescence intensity upon addition of 4 equivalents of various amino acids; the second bars represent the fluorescence intensity after subsequent addition of 2 equivalents of GSH to the non-sulfhydryl amino acids solution, respectively.</p

Synthesis procedures of the thiols probe (compound 1-Cu²⁺).

<p>Synthesis procedures of the thiols probe (compound 1-Cu²⁺).</p

Fluorescence responses of compound 1-Cu²⁺ (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution upon the addition of increasing GSH.

Insert: fluorescence titration profile at 483 nm upon the addition of GSH (excited at 445 nm).</p

UV-vis titration of compound 1 (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution upon addition of Cu²⁺.

<p>Inset: UV-vis titration profile of compounds <b>1</b> upon addition of Cu²⁺, the absorption was recorded at 480 nm.</p

Fluorescence emission spectra of compound 1 (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution with successive addition of Cu²⁺.

<p>Insert: fluorescence titration profile at 483 nm upon the addition of Cu²⁺ (excited at 445 nm).</p