Fig. 26. UV-vis absorption spectra of 119 upon addition of 5 equiv. of salts (Na⁺, K⁺, Ag⁺, Cu⁺, Mg²⁺, Zn²⁺, Ca²⁺, Sn²⁺, Cu²⁺, Ni²⁺, Mn²⁺, Pb²⁺, Cd²⁺, Ba²⁺, Hg²⁺, Fe²⁺, Co²⁺, Fe³⁺, Al³⁺ and Cr³⁺ in a CH₃CN/HEPES. Colorimetric response of 119 with Co²⁺.