One-Pot 'Click' Synthesis of Ring-in-Rings Complexes with Customizable π-Stacked Dyads

We report an efficient one-pot aqueous synthesis of ring-in-rings complexes featuring customizable π-stacked dyads. Conventional methods for such complexes often suffer from poor solubility and low yields due to irreversible kinetically controlled reactions. To overcome these limitations, we developed a strategy combining noncovalent preassembly with efficient dynamic covalent bonding to secure a ring-in-rings complex as the exclusive thermodynamic product. Through complexation with cucurbit[8]uril (CB[8]), a folded conformation was induced in an aldehyde-functionalized bis(phenylpyridinium) derivative, predisposing the reactive aldehyde groups to promote acylhydrazone condensation with aromatic dihydrazides. The method achieves high conversion and purity, enabling direct single-crystal growth without the need for purification. We successfully synthesized π-stacked dyads across diverse aromatic moieties, including five distinct single-crystal structures demonstrating dimeric cofacial stacking. Kinetic analysis reveals that CB[8] complexation increases the ceiling temperature of the condensation reaction, rendering the process both thermodynamically and kinetically favorable. The modular nature of this strategy allows for precise tuning of photophysical properties by simply altering the linker lengths and the central aromatic cores, providing a facile platform for exploring structure-function relationships in ring-in-rings complexes and beyond.