Fig. 2: Mechanical activation of chain-centred knot 1, gate 2 and linear ligand 3.
a, Mechanical activation of chain-centred knot 1 and isolation of the resulting fragments. Conditions: (i) ultrasound (20 kHz, 11.5 W cm−2, 1 s on/2 s off), CH3CN, 5–10 °C, 180 min; (ii) NaOH. b, The overlay of gel-permeation chromatography traces at various sonication times of chain-centred knot 1 (tetrahydrofuran, 1 ml min−1) is consistent with a rupture in the central region of the polymer. c, Partial 1H NMR (500 MHz, CDCl3) spectra of knot 1 before (i) and after (ii) sonication, along with a reference compound (iii), indicate opening of the gate adduct through mechanical activation. d, Mass spectrometry (electrospray ionisation high-resolution mass spectrometry, negative ion mode) identification of fragments 4, 5 and 6 in the hydrolysed post-sonication mixture. e, Structure of chain-centred gate (2) and linear ligand (3). f, Dissociation kinetics of chain-centred knot (1), gate (2) and linear ligand (3). Mt = Mn at time t, M0 = Mn at 0 min. Solid lines correspond to a linear fit; R2 (goodness of fit) = 0.963, 0.976 and 0.988 for 1, 2 and 3, respectively. Each point corresponds to the average of three sonication experiments. Data are presented as means ± s.e.m. Coloured areas indicate 95% confidence levels.
