Fig. 1

A Fluorescence spectra of HTI (10 μM) in water and various organic solvents. B Fluorescence spectra of HTI (10 μM) in mixed solvents with different proportions of methanol and glycerin. C Dependence of Log I on Log η. Log(I₆₁₇) = 0.3419 log η + 1.709 (R² = 0.9935). D Fluorescence responses of HTI (10 μM) for various analytes in H₂O or H₂O/Gly (1/1, v/v). Analytes (HTI, 10 μM; other analytes, 100 μM): 1, Only probe; 2, Zn(OAc)₂; 3, FeSO₄; 4, CoCl₂; 5, CaCl₂; 6, MgSO₄; 7, NaF; 8, NaBr; 9, NaI; 10, KO₃; 11, NaNO₂; 12, Na₂SO₃; 13, H₂O₂; 14, Glucose; 15, Cys; 16, Tyr; 17, Pro; 18, Gly; 19, Val; 20, Ala. λ_ex = 500 nm. E UV–vis absorption spectra of ABDA (50 μM) with HTI (10 μM) upon various periods of white light irradiation (60 mW cm⁻²). F Changes of absorption intensity of ABDA solution at 378 nm upon irradiation for different times