We recently did a lab/demo using the NMR to observe Na ions in sodium complexes in our Inorganic Class. I understand most of the post lab questions, but there are a few that still have me stumped. Essentially what we did was create two samples: in one we added NaI to 18-crown-6 ether (with enough deuterated acetone to lock the signal) and in the other we just added NaI to deuterated acetone. 1M NaCl was used as a standard. The resulting peak of the Crown solutiion was shifted downfield approximately -17 ppm from the NaCl standard. The peak from the Na in pure acetone was only about -1.7 ppm down from the standard. My questions are as follows:

1) How would you make the Na-23 NMR peaks "sharper" for NaI/18-crown-6 ether samples?

2)Why did we acquire all spectra without rotationg the sample?

3) Why are Na-23 peaks shifted to lower ppm values when sodium is encapsulated by 18-crown-6 ether

4) How would our results change if a cryptand, such as [2,2,2]crypt was used instead of 18-crown-6 ether.