Allosteric Binding‐Induced Intramolecular Mechanical‐Strain Engineering

• Published in: Angewandte Chemie Vol. 134; no. 18
• Main Authors: Ma, Wenxian, Cheng, Tingting, Liu, Fang‐Zi, Liu, Yan, Yan, KaKing
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 25.04.2022
• Subjects: Alkanes; Allosteric properties; Binding; Chemical bonds; Chemistry; Cleavage; Conformation; Conformational analysis; Covalent bonds; Helix Inversion; Host–Guest Chemistry; Mechanochemistry; Molecular Switch; Polymers; Reactivity; Strain; Supramolecular Chemistry; Zinc
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202202213

Recently, polymer mechanochemistry has attracted much scientific interest due to its potential to develop degradable polymers. When the two ends of a polymer chain experience a linear pulling stress, molecular strain builds up, at sufficiently strong force, a bond scission of the weakest covalent bond results. In contrast, bond‐breaking events triggered by conformational stress are much less explored. Here, we discovered that a Zn salen complex would undergo conformational switching upon allosteric complexation with alkanediammonium guests. By controlling the guest chain length, the torsional strain experienced by Zn complex can be modulated to induce bond cleavage with chemical stimulus, and reactivity trend is predicted by conformational analysis derived by DFT calculation. Such strain‐release reactivity by a Zn(salen) complex initiated by guest binding is reminiscent of conformation‐induced reactivity of enzymes to enable chemical events that are otherwise inhibited. Analogous to allosteric enzymes, guest binding introduces a directional pulling or pushing force that acts on the reverse side of a Zn salen complex. This tunable intramolecular force promotes various degrees of conformational and torsional strain, as predicted by both classical conformational analysis and DFT. This strain energy can be further applied to cleave chemical bonds, and the efficiency can be tuned by the identity of allosteric guest.