Figure 1 (a) Schematic representation of the self-assembly ofM1- based SPs to form Poly[2]catenane networks by addingM2 and M3 . (b) 1H NMR spectra (400 MHz, CDCl3, 298 K) of (I) M1 , (II) M3 , a mixture of 50 mmol M1 and 5 mmol M3 after (III) 2 h, (IV) 4 h, (V) 8 h, and (VI) 20 h. (c) 1H NMR spectra (400 MHz, CDCl3, 298 K) of (I) M1 , (II)M3 , (III) M2 , a mixture of 50 mmol M1 , 5 mmolM3 and 90 mmol M2 after (IV) 2 h, (V) 4 h, (VI) 8 h, and (VII) 20 h. (d) FT-IR spectra of M1 , M2 ,M3 , the mixture of M1 (50 mmol) and M3 (5 mmol), M1 (50 mmol) and M2 (90 mmol), M1 (50 mmol), M2 (90 mmol) and M3 (5 mmol). Note that all the mixtures were first dissolved M1 in solvent for 15 min before the addition of other monomers (M2 , M3 ) to ensure the formation of SPs first.
As shown in Figure 1c, 0.1 equiv. of M3 and 1.8 equiv. ofM2 were added into 50 mmol M1 , this was done in order to keep the amount of aldehyde groups in M2 and M3 consistent with the amounts of amino groups in the M1 -based SPs. The aldehyde peaks of M2 and M3 were almost no longer decreasing after 8 h, while at the same time the imide peaks that appeared in the range of 8.20-8.50 ppm were no longer changing. This proved that the reaction between the amino groups of M2 ,M3 and the M1 -based SPs promoted to generate imine bonds.[23] Infrared spectroscopy (IR) assessments were also conducted on M1 , M2 , M3 , as well as their mixture corresponding M1 and M2 , M1 andM3 , M1 , M2 and M3 . As shown in Figure 1e, compared to the individual spectra of M1 ,M2 , and M3 , it could be found that the vibrational peaks of the spectra of their mixtures were distinctly different: a C=N stretching vibration peak at 1654 cm-1 was detected in the mixtures. These results also proved that M1 reacted withM2 and M3 .[24]