Pentacyclic Nano-Trefoil.

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Cyclen-based ligands are versatile scaffolds in coordination chemistry.
• Silver(I) complexes with macrocyclic ligands can exhibit interesting structural dynamics.
• Selective guest encapsulation in solid-state is a key challenge in host-guest chemistry.

Purpose of the Study:

• To synthesize and characterize novel tetra-armed cyclen ligands and their silver(I) complexes.
• To investigate the structural transformations of silver(I) complexes with varying molar ratios.
• To explore the solid-state encapsulation capabilities of the resulting complexes, particularly for benzene.

Main Methods:

• Synthesis of a tetra-armed cyclen ligand with pyridylbenzyl and difluorobenzyl groups.
• Preparation and structural characterization of silver(I) complexes using techniques like X-ray crystallography.
• Analysis of reversible structural transformations between dimeric and pentacyclic trefoil complexes.
• Investigation of selective benzene and deuterated benzene encapsulation in the solid state.

Main Results:

• A novel tetra-armed cyclen ligand (1) and its silver(I) complexes were successfully prepared and characterized.
• Reversible structural transformation between 2:2 dimeric and 3:5 pentacyclic trefoil complexes was observed based on Ag+/1 molar ratio.
• The 3:5 trefoil complex demonstrated selective encapsulation of benzene and [D6]benzene in the solid state.
• Benzene inclusion was stabilized by specific C-H···F-C interactions between the guest and the ligand.

Conclusions:

• Tetra-armed cyclen ligands can form dynamic silver(I) complexes with tunable structures.
• The pentacyclic trefoil complex exhibits selective host-guest properties for aromatic molecules.
• C-H···F-C interactions play a crucial role in stabilizing the encapsulated guest molecules in the solid state.