Reversible Adaptation to Photoinduced Shape Switching by Oligomer–Macrocycle Interconversion with Component Selection in a Three‐State Constitutional Dynamic System

Light irradiation of the molecular photoswitch 1 ‐E causes isomerization into the 1 ‐Z configuration stabilized by an internal hydrogen bond. 1 ‐E bears aldehyde groups allowing for dynamic covalent reaction with linear diamines. On photoinduced E/Z shape switching of 1 in presence of diamines, the system undergoes interconversion between two states, a non‐cyclic oligomeric one and a macrocyclic one, corresponding respectively to the E and Z configurations of 1 . With a mixture of linear α,ω‐diamines, 1 ‐E yields non‐selective dynamic oligomers by random incorporation of diamine components. Photoswitching to the 1 ‐Z form leads to constitutional adaptation with preferential formation of the macrocycle incorporating the best suited diamine, H₂N(CH₂)₇NH₂. In presence of metal cations, the E form switches from its unbound W shape to its coordinated U shape and yields the macrocycle resulting from the selective incorporation of the diamine H₂NCH₂CH₂OCH₂CH₂NH₂ that contains an additional O coordination site. Taken together, the results obtained describe constitutional adaptation in a triple state system: an oligomeric one and two different macrocyclic ones generated in response to two orthogonal agents, a physical stimulus, light, or a chemical effector, metal cations. These three states present, towards the incorporation of diamine components, respectively no selection, photoselection and metalloselection.