Constructing π-Stacked Supramolecular Cage Based Hierarchical Self-Assemblies via π···π Stacking and Hydrogen Bonding

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Coordination Chemistry

Background:

• Constructing complex supramolecular cages from multiple subunits via weak interactions is challenging.
• π-stacked supramolecular cages have remained largely unexplored.
• Hierarchical self-assembly offers a route to intricate molecular architectures.

Purpose of the Study:

• To report the first series of π-stacked supramolecular cages (π-MX-cages).
• To investigate the hierarchical self-assembly of these cages.
• To demonstrate the versatility of π-MX-cages in encapsulating various guest molecules and stabilizing reactive species.

Main Methods:

• Assembly of π-MX-cages from 16 [MXL]+ ions (M = Mn2+, Co2+; X = Br-, SCN-, Cl-; L = tris(2-benzimidazolylmethyl)amine) utilizing 18 intermolecular π-stacking interactions.
• Characterization of tetrahedral cage structures with vertexes and edges formed by [MXL]+ ions.
• Exploration of guest encapsulation and hierarchical superstructure formation by varying M2+/X- pairs.

Main Results:

• Successful synthesis of π-stacked cages (π-MX-cages) with tetrahedral geometry.
• Demonstrated hierarchical self-assembly driven by π-stacking and hydrogen bonding.
• π-MnBr-cages encapsulated acetonitrile or cis-1,3,5-cyclohexanetricarbonitrile and inorganic clusters.
• π-CoSCN-cages stabilized reactive sulfur-containing species.
• π-CoCl-cages facilitated the formation of inorganic mesoporous frameworks with H2PO4- ions.

Conclusions:

• The study presents a novel class of π-stacked supramolecular cages.
• These cages exhibit remarkable versatility in hierarchical self-assembly and guest incorporation.
• The findings open new avenues for designing functional supramolecular materials based on π-π stacking interactions.