Figure 3.

(a) Temperature-dependent changes in the UV–vis absorption spectrum of trans-SG1 (0.4 mM) in toluene during cooling at a rate of 1.0 K/min. (b) Cryo-TEM image of SP-SG1 formed by trans-SG1 (0.4 mM) after supramolecular polymerization in toluene. (c) Calculated self-assembled structure of trans-SG1 using the ONIOM approach (wB97X-D/def2SVP//wB97X-D/6-31G(d)//UFF). The distance between the urea groups in the dimer is 1.8 nm. (d) Degree of aggregation (α_agg, estimated from the UV–vis absorption at 373 nm) of trans-SG1 (c_T = 0.4 mM) as a function of temperature upon cooling and heating at different rates (0.5–2.0 K/min). (e) Natural logarithm of the reciprocal of c_T as a function of the reciprocal of T_e (van’t Hoff plot). (f) Schematic illustration of the nucleation–elongation process of trans-SG1.³²