Fig. 6. Normalised sinusoidal curves for the respective protagonist IR bands listed in Table S2.† All signals are normalised between 0 and 1, with the response at 3655 cm^–1 ([Cu²⁺(OH^–)]⁺) set to 0° phase angle and all other species adjusted accordingly. These species are listed in Table S2† and correspond to band intensity responses due to black = 1258 cm^–1, red = 1436 cm^–1, blue = 1606 cm^–1, green = 2158 cm^–1, purple = 3182 cm^–1, orange = 3655 cm^–1.