Synthesis and Multisite Host–Guest Recognition of Unsymmetrical Tetraphenylethene-Based Hexacationic Cages

Abstract

The development of robust synthetic methodologies for constructing persistent molecular hosts including macrocycle and cage structures represents a central objective in supramolecular chemistry, enabling precise host–guest recognition in solution. In this work, we efficiently synthesized a series of unsymmetrical hexacationic molecular cages (1–3) based on tetraphenylethene (TPE) building blocks. These cages possess unsymmetrical cavities that integrate structural rigidity with conformational adaptability, thereby enabling multisite recognition polycyclic aromatic hydrocarbons (PAHs) in organic media and hydrophobic near-infrared dyes in aqueous media through multiple noncovalent interactions. These combined interactions significantly enhance host–guest binding affinity. Moreover, the effective host–guest complexation facilitates efficient fluorescence resonance energy transfer (FRET) from the cage to encapsulated dye guests. This work not only provides a straightforward strategy for constructing unsymmetrical molecular cages but also establishes a versatile platform for the development of high-performance molecular recognition systems and photofunctional materials.