Halogen bonding versus hydrogen bonding induced 2D self-assembled nanostructures at the liquid-solid interface...

Area of Science:

• Supramolecular chemistry
• Materials science
• Surface science

Background:

• Understanding molecular self-assembly is crucial for designing advanced materials.
• Controlling intermolecular interactions, such as hydrogen and halogen bonds, is key to directing self-assembly.
• The liquid-solid interface offers a unique platform for studying self-organized nanostructures.

Purpose of the Study:

• To investigate the 2D self-assembly of a novel bifunctional molecule, 5-bromo-2-hexadecyloxy-benzoic acid (5-BHBA).
• To explore the influence of different solvents and concentrations on the self-organization of 5-BHBA.
• To elucidate the roles of cooperative and competitive halogen and hydrogen bonds in directing nanoarchitecture formation.

Main Methods:

• Experimental investigation using scanning tunneling microscopy (STM).
• Theoretical analysis using density functional theory (DFT) calculations.
• Study of self-assembly at the liquid-solid interface in 1-octanoic acid and n-hexadecane solvents.

Main Results:

• Formation of distinct nanoarchitectures (dimers, trimers, tetramers) in 1-octanoic acid driven by various intermolecular interactions.
• Observation of self-assembled linear patterns in n-hexadecane, primarily through hydrogen bonding.
• Demonstration that solvent polarity and molecule-solvent interactions dictate the balance of cooperative and competitive bonding.

Conclusions:

• The interplay of halogen and hydrogen bonds effectively controls 2D self-assembled nanostructures at the liquid-solid interface.
• Solvent choice significantly impacts the type and stability of self-assembled patterns.
• This research provides novel insights into designing and inducing specific 2D nanostructures through tailored intermolecular interactions.