Robust Organic Radical Molecular Junctions Using Acetylene Terminated Groups for C-Au Bond Formation

Area of Science:

• Molecular electronics
• Organic spintronics
• Materials science

Background:

• Organic paramagnetic and electroactive molecules are key for molecular electronics and spintronics.
• Current limitations include poor stability and reproducibility of molecule/electrode contacts.

Purpose of the Study:

• To synthesize a persistent organic radical with terminal alkyne groups for forming Au-C σ bonds.
• To investigate the stability of self-assembled monolayers and electron transport in single-molecule junctions.

Main Methods:

• Synthesis of organic radical with alkyne functionalities.
• Formation and characterization of self-assembled monolayers on gold.
• Measurement of electron transport through single-molecule junctions.
• Density functional theory and quantum transport calculations.

Main Results:

• The synthesized linker forms robust covalent Au-C σ bonds.
• This leads to more stable self-assembled monolayers and better-defined molecule/electrode contacts compared to sulfur-based linkers.
• Single-molecule junctions exhibit reduced variability in conductance values.
• Experimental and computational results align, confirming the enhanced junction properties.

Conclusions:

• Alkynyl linkers provide a robust and reproducible method for interfacing electroactive molecules with gold electrodes.
• This approach overcomes limitations of traditional sulfur-based linkers.
• The findings pave the way for more reliable molecular electronic and spintronic devices.