Surface-Confined Macrocyclization via Dynamic Covalent Chemistry

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Surface-confined synthesis offers a route to complex molecular nanostructures like macrocycles.
• On-surface macrocyclization faces challenges in selectivity for monodisperse and multicomponent structures.

Purpose of the Study:

• To report the on-surface formation of [6 + 6] Schiff-base macrocycles via dynamic covalent chemistry.
• To investigate methods for selective synthesis of monodisperse macrocycles on surfaces.
• To understand the factors influencing macrocycle formation over oligomers or polymers.

Main Methods:

• Utilized dynamic covalent chemistry for on-surface macrocyclization.
• Employed in situ scanning tunneling microscopy (STM) for real-time imaging.
• Integrated density functional theory (DFT) and molecular dynamics (MD) simulations for mechanistic insights.

Main Results:

• Achieved formation of two-dimensional crystalline domains of [6 + 6] Schiff-base macrocycles.
• Demonstrated control over product formation (oligomers, macrocycles, polymers) by adjusting alkyl substituent length.
• Identified synergistic effects of surface confinement and solvent in promoting macrocyclization.

Conclusions:

• On-surface dynamic covalent chemistry enables the selective synthesis of well-defined macrocycles.
• Alkyl chain length is a critical parameter for controlling supramolecular assembly on surfaces.
• Surface confinement and solvent play crucial roles in directing molecular self-assembly and macrocyclization.