Jozef Hodyl PhD Thesis - Theses - Flinders University

spectrum for the material was then attained at a spin rate of 5 kHz with a recycledelay time of 4 s utilising TOSS (TOtal Suppression of Spinning Sidebands)software to eliminate the appearance of spinning side-bands. Solution 13 C NMRspectra (proton decoupled) were also obtained in DMSO-d 6 for the guest species toallow chemical shift assignment of their resonances, for example, as shown inFigure 6.6 for 2,6-dihydroxybenzoic acid and 2,6-dihydroxybenzoate.180 160 140 120 100 ppm 180 160 140 120 100 ppmFigure 6.6 Solution 13 C{ 1 H} NMR spectra of (A) 2,6-dihydroxybenzoic acid and (B) sodium 2,6-dihydroxybenzoate obtained in DMSO-d 6 .Both of the above spectra show sharp singlet resonances for each of the fiveinequivalent carbon atoms present in 2,6-dihydroxybenzoic acid and 2,6-dihydroxybenzoate. However, the 13 C spectra seen in solution do not mirror thoseseen in the 13 C solid state NMR, as evidenced by the spectra obtained for 2,6-dihydroxybenzoic acid and sodium 2,6-dihydroxybenzoate, depicted in Figure 6.7.Spectra A and B for 2,6-dihydroxybenzoic acid and sodium 2,6-dihydroxybenzoate show line broadening with extra resonances for C3 and C4 in2,6-dihydroxybenzoic acid, and C3, C4 and C5 in sodium 2,6-dihydroxybenzoate.113