Fig. 6. (A) Chemical structures of bis-urea benzene derivatives; (B) comparison of solution, gel and solid state 13C NMR spectra of 4a: (a) 61.1 mM in DMSO-d 6; (b) 5.4 mM in CDCl3; (c) 47.7 mM in CDCl3; (d) 13C CP MAS NMR of the solid and (e) toluene-d 8 gel of 4a. Reproduced with permission from ref. 42 © Wiley-VCH.
