The cucurbit[7]uril effect on reference substances for NMR in deuterium oxide solution

Abstract

The effect of macrocyclic molecule cucurubit[7]uril on the chemical shifts of internal reference substances for NMR studies in deuterium oxide solution and the cause were investigated.

Ambient temperature 1H/13C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D2O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples

“…For example, recent work on the cucurubit [7]uril system revealed large shifts of methyl lines from DSS and TSP to lower frequencies. 8 Thus, as shown above, the behavior of the trimethylsilyl (Me 3 Si) group of DSS or TSP can still be a 'surprise'. However, in my opinion, some information on using DSS as an NMR standard has generally been incomplete in the literature, especially for its 13 C nuclei.…”

“…As a result, DSS is widely used with varying success. For example, recent work on the cucurubit[7]uril system revealed large shifts of methyl lines from DSS and TSP to lower frequencies 8 . Thus, as shown above, the behavior of the trimethylsilyl (Me 3 Si) group of DSS or TSP can still be a ‘surprise’.…”