Figure 6.

One-dimensional NMR spectra of CH and FOS. (A) Comparison of ¹H NMR spectra of 1 mM FOS (blue), 3 mM CH (red), and a mixture of the two (black) at pH 6.5. This spectrum was unchanged after 6 days. (B) ³¹P-NMR spectra of 1 mM FOS with 3 mM CH. No ring-opened FOS (~16 ppm) was observed after 6 days. (C) ³¹P-NMR spectrum of 1 mM FOS and 104 mM CH at pH 6.5. The broadened FOS signal was much harder to detect.