Chiral nanostructuring of multivalent macrocycles in solution and on surfaces

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Synthesis

Background:

• Development of homochiral macrocycles is crucial for creating complex molecular architectures.
• Introducing multivalency and controlled self-assembly are key challenges in macrocyclic chemistry.
• Chiral nanostructures have significant potential in catalysis, sensing, and advanced materials.

Purpose of the Study:

• To design and synthesize a novel, functionality-rich, homochiral macrocycle with D2 symmetry.
• To explore the self-assembly behavior of the macrocycle upon metal ion coordination.
• To investigate the formation of chiral nanostructures using the macrocycle-metal hybrid and C60.

Main Methods:

• Synthesis of a homochiral macrocycle using enantiopure 1,1'-binaphthyl synthons via room temperature esterification.
• Coordination chemistry involving the macrocycle's pyridine moieties and Pd(2+) ions.
• Circular dichroism spectroscopy to detect macrocyclic conformational changes.
• Surface-confined nanostructuring experiments with the macrocycle-Pd(2+) hybrid and C60.

Main Results:

• Successful synthesis of a D2-symmetric, homochiral macrocycle incorporating four pyridine units for multivalency.
• Formation of chiral ordered mono-, dimeric macrocycles, or multimeric aggregates upon Pd(2+) addition, dependent on solvent and conditions.
• Observation of significant macrocyclic conformational rearrangement upon metal binding.
• Generation of chiral nanofibres through surface-confined nanostructuring of the macrocycle-Pd(2+) hybrid with C60.

Conclusions:

• The novel homochiral macrocycle serves as a versatile platform for constructing ordered supramolecular assemblies.
• Pd(2+) coordination induces predictable self-assembly and conformational changes, leading to chiral architectures.
• The macrocycle-Pd(2+)-C60 system enables the formation of functional chiral nanofibres, opening avenues for advanced nanomaterials.