Fig. 7. (a) Substrate induced generation of a macromolecular catalyst. The cyclic substrate 13 promotes the dimerization of the catalyst M to form an active ternary complex M213, capable of catalyzing a decarboxylative Mannich reaction. (b) Conversion of 13 over time with the varying mol% of the macromolecular catalyst. (c) Change of the initial reaction rate with varying concentration of the macromolecular catalyst. Adapted from ref. 32 with permission from John Wiley and Sons. (d) The presence of a threshold amount of Zn²⁺ (>20 mol%) induces the formation of catalytic complex 17 that initiates a cascade of events to yield 21 which sequestrates Zn²⁺ away from 17, leading to restoration of 16 and subsequent loss of catalytic ability. (e) Formation of 21 was achieved only after the addition of a certain threshold concentration of zinc(ii) to a mixture of 16, 18 and 20. Adapted from ref. 33 with permission from the American Chemical Society.