Dynamic covalent chemistry (DCvC) has been strongly integrated into diverse research fields, and has enabled easy access to a variety of combinatorial libraries, 2-D macrocycles, and 3-D molecular cages that target many important applications, such as drug discovery, biotechnology, molecular separation, light harvesting, etc. DCvC relies on the reversible formation and breaking of rather strong covalent bonding within molecules. Therefore it combines the error-correction capability of supramolecular chemistry and the robustness of covalent bonding. Compared to those supramolecular interactions, dynamic covalent reactions usually have slower kinetics and require the assistance of catalysts to achieve rapid equilibrium. Although the scope of dynamic covalent reactions is rapidly expanding, the reversible reactions suitable for DCvC are still very limited. The identification and development of new dynamic reactions and catalysts would be critical for the further advancement of DCvC. This review covers the recent development of dynamic covalent reactions as well as their applications.

A series of phenylene vinylene macrocycles (PVMs) bearing substituents with various sizes and electronic properties have been synthesized through a one-step acyclic diene metathesis macrocyclization approach and their aggregation behaviors have been investigated. In great contrast to the aggregation of the analogous phenylene ethynylene macrocycles, which aggregate only when substituted with electron-withdrawing groups, these PVMs undergo exceptionally strong aggregation, regardless of the electron-donating or -withdrawing characters of the substituents. The unusual aggregation behavior of the PVMs is further investigated with thermodynamic and computer modeling studies, which show a good agreement with the recently proposed direct through-space interaction model, rather than the polar/π model. The high aggregation tendency of PVMs suggests the great potential of this novel class of shape-persistent macrocycles in a variety of applications, such as ion channels, host-guest recognition, and catalysis.

The title macrocycles (PVMs) are obtained in one step.

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