Figure 5.

Selective cyclic tetramer dissociation. (a–d) Temperature-dependent CD spectra in toluene of (a) a 1:1 GdC + Aa₁U mixture, (b) a 1:1 AdU + Ga₁C mixture, (c) a 1:1:1 iGiC + Aa₁U + Ga₂C mixture, and (d) a 1:1:1 GdC + Ga₁C + Ga₂C mixture. (e, f) Downfield region of the ¹H NMR spectra of a 1:1 mixture of GC + AU in (e) CDCl₃ with increasing temperature or (f) CDCl₃:CCl₄ (2:3) with increasing DMSO-D₆ content. (g) Downfield region of the ¹H NMR spectra of a 1:1 mixture of GC + iGiC in CDCl₃ with increasing DMSO-D₆ content. In the last mixture, the ¹H signals of the c(iGiC)₄ species are initially broad due to strong aggregation in pure CDCl₃. A small amount of DMSO needs to be added to achieve complete solubility. For proton NMR codes, see Figure 1.