Symmetry-Regulated Argentophilic Interactions via Homochiral Proline Dodecamers

Although the argentophilic interaction has been reported in the ligand-supported interactions in crystal engineering, the controllable chemical flexibility of such an interaction, which can alter the properties of corresponding materials in response to changes, is very lacking. To fulfill such a task, providing a flexible surrounding to support metallophilic interaction is the key. Herein, we reveal that the controllable argentophilic interaction within the confined domain of a homochiral proline dodecamer complex, [(l-Pro)₁₂+2Ag]²⁺ is possible. By combining electrospray ionization mass spectrometry, infrared photodissociation spectroscopy, and quantum chemical calculations, we show that the <i>C</i>₃-symmetric proline dodecamer encapsulates two silver ions, manifesting a caged argentophilic interaction and enhanced homochiral selectivity for the unit of proline. It reveals the existence of both argentophilic interaction or a four-center two-electron bonding motif is possible, underscoring the intricate interplay between symmetric constraints and electronic effects within the confined domain. This job shows the new possibility of constructing flexible domain-confined secondary interactions with self-assembling of designed biomolecules, marking the roles of symmetry and electron transformation on the controllability of such interactions.