Figure 2. Synthesis and characterization of s-Gel.

(a) Synthesis and schematic representation of s-Gel. DMF = N,N-dimethylformamide. (b) UV-vis spectrum of s-Gel (black line) showing the red-shifting of λ_max to 724 nm compared to copper acetate (red line). This red shift is indicative of the formation of Cu-m-BDC paddlewheel complexes. (c) SAXS/WAXS curve depicting the spacing between Cu₂₄L₂₄ MOCs within s-Gel as well as the form factor of MOC junctions. (d) Frequency sweep rheology curve for s-Gel (5.3 wt. %) swollen to equilibrium in DMF. (e) Stress relaxation data for s-Gel. The red line corresponds to fitting of the data using the Kohlrausch stretched exponential model, which provide the characteristic relaxation time τ. Inset: Image of s-Gel cut into several pieces (left). Placing the mashed sample in a mold and applying pressure leads to complete healing (right).