Fig. 9

The color changes upon gradual addition of different equiv. of cyanide anion (A) upon addition of 10 equiv. of different anions (B) and upon mixing 10 equiv. of cyanide anion and another competing anion (5 equiv. + 5 equiv. each) (C). A Image of CN⁻ responsive PTZON (from left to right: 0–10 equiv.); B in the presence of 10 equiv of different anions (from left, CN⁻, Br⁻, I⁻, F⁻, Cl⁻, NO₃⁻, NO₂⁻, SO₄²⁻, AcO⁻, ClO₄⁻, blank); c in the presence of 5 equiv. of CN⁻ and 5 equiv. of different anions (from left, blank, Br⁻, I⁻, F⁻, Cl⁻, NO₃⁻, NO₂⁻, SO₄²⁻, AcO⁻, ClO₄⁻, CN⁻)