Precision Nanocluster-Based Toroidal and Supertoroidal Frameworks Using Photocycloaddition-Assisted Dynamic Covalent...

Area of Science:

• Nanotechnology
• Materials Science
• Supramolecular Chemistry

Background:

• Atomically precise nanoclusters (NCs) are building blocks for self-assembled superstructures.
• Current methods rely on non-covalent interactions, limiting reversible assembly.
• Long-range reversible self-assembly via dynamic covalent chemistry on NCs remains unexplored.

Purpose of the Study:

• Investigate long-range reversible self-assembly of NCs using dynamic covalent chemistry.
• Demonstrate the formation of hierarchical superstructures via photocycloaddition reactions.
• Explore applications in photocontrolled drug delivery.

Main Methods:

• Synthesis of Au25 nanoclusters with thiolated umbelliferone ligands.
• Utilizing [2+2] photocycloaddition for self-assembly.
• Characterization using electron microscopy, AFM, and electron tomography.
• Demonstration of a drug release model using 5-fluorouracil.

Main Results:

• Au25 NCs self-assemble into colloidal toroids via photocycloaddition.
• Toroids further assemble into macroscopic supertoroidal honeycomb frameworks.
• Demonstrated reversible loading and unloading of an anticancer drug.
• Hierarchical assembly from spherical aggregates to toroids to honeycomb structures observed.

Conclusions:

• Dynamic covalent chemistry on NC surfaces provides a route for hierarchical multifunctional frameworks.
• Photocontrolled assembly and disassembly enable applications in drug delivery.
• This approach offers facile construction of advanced nanomaterials.