Fig. 10. (A) ¹³C NMR spectra of compound 6b; (a) solution state; (b) ¹³CP MAS NMR spectrum of the synthesis product recrystallized from acetonitrile; (c) ¹³C CP MAS NMR spectrum of 2% (w/v) benzene gel. (B) ¹³C NMR spectra of compound 6c; (a) solution state; (b) ¹³C CP MAS NMR spectrum of the synthesis product recrystallized from acetonitrile and (c) ¹³C CP MAS NMR spectrum of 4% (w/v) toluene-d ₈ gel. Reproduced with permission from ref. 45 Copyright © 2010 Royal Society of Chemistry.