Single-Molecule Conductance Behavior of Molecular Bundles

Area of Science:

• Molecular electronics
• Supramolecular chemistry
• Surface science

Background:

• Controlling molecular orientation in junctions is key for functional molecular devices.
• Current methods using multipodal compounds offer control but reduce surface coverage.
• An alternative approach is needed to enhance orientation control and surface coverage.

Purpose of the Study:

• To investigate a novel method for creating multimodal compounds by forming molecular bundles via metal coordination.
• To assess the surface binding and conductance properties of these molecular bundles.
• To determine if this approach offers improved control over junction geometry without compromising individual molecular wire function.

Main Methods:

• Synthesis of iron(II) and cobalt(II) complexes with specific bipyridine and bis(methanimine) ligands.
• Characterization of complexes using X-ray photoelectron spectroscopy (XPS) for surface binding analysis.
• Measurement of single-molecule conductance and density functional theory (DFT) calculations to evaluate electronic properties.

Main Results:

• Successfully formed monometallic and bimetallic complexes (molecular bundles).
• XPS confirmed all complexes bind to gold surfaces via thiomethyl groups in a specific orientation.
• Single-molecule conductance and DFT calculations showed each molecular wire functions independently within the bundle.

Conclusions:

• Metal-coordinated molecular bundles offer a viable strategy for controlling molecular junction geometry.
• This approach achieves good surface coverage while preserving the intrinsic conductance of individual molecular wires.
• The findings present a promising pathway for developing advanced molecular electronic devices.