Figure 2
From: Make Caffeine Visible: a Fluorescent Caffeine “Traffic Light” Detector
NMR titration experiments of CO against caffeine.
(a)1H NMR titration of CO with caffeine (amine). From bottom spectrum to top spectrum, they represent different molar ratios of CO against caffeine, from pure CO (n = 0) to much caffeine excess (n = 32). n is the equivalent of caffeine to CO. (b)1H NMR titration of CO with caffeine (7.70–6.30 ppm range). Inset refers to the proton labelling scheme. The detailed NMR condition has been depicted in Methods.
