Fig. 5: 1H NMR of the rotaxane translational isomers.
From: Controlled assembly of rotaxane translational isomers using dual molecular pumps
Comparison of the 1H NMR spectra of (a) DP•6PF6 and its rotaxane translational isomers, (b) R1•10PF6, (c) R2•10PF6, (d) R3•14PF6, and e R4•14PF6. Spectra were recorded in CD3CN at 298 K and a field strength of 600 MHz. Key shifts demonstrating the mechanically interlocked nature of these compounds, and the changes between pumping cycles, are labeled. In particular, the presence of a CBPQT4+ ring on the central collecting chain, as in R1•10PF6 and R3•14PF6, is demonstrated by the upfield shift of H-16 of the linker and H-17 of the triazole unit from the aromatic region to 3.5–4.5 ppm. Rings on the terminal chain; as in R2•10PF6, R3•14PF6, and R4•14PF6; are evidenced by the upfield shifting of the H-42 to H-49 alkane resonances. The additional ring density of R4•14PF6 results in upfield shifting of H-35 of the second IPP unit.
