Fig. 2. (a) Time-dependent absorption changes (0–120 min: purple to blue; 120–400 min blue to orange) of L1 (5 × 10–4 M) in MCH after irradiation for 30 min with a 370 nm LED lamp at 283 K; inset: plot of A360vs. time at 283 K, and photographs showing the irradiated clear L1cis + trans monomer (left) to turbid L1trans aggregates (right). (b) Time-dependent 1H-NMR changes at 283 K of L1 (5 × 10–4 M) after irradiation for 30 min with a 370 nm LED lamp in MCH-d14. Black encircled green peaks correspond to cis isomer. (c) Scheme showing reversible trans–cis isomerization. (d) AFM image of L1 (5 × 10–4 M) on HOPG upon UV-irradiation for 30 min in MCH and ageing at 283 K for 400 min with corresponding cross-section analysis along the yellow line.
