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Enhanced electronic coupling in tetraaryl molecular junctions with osmium(iv) centers
Luana Zagami1, Mukund Sharma1, Andrew Fraire1
1Department of Chemistry, University of Southern California Los Angeles CA 90089 USA.
Chemical Science
|June 25, 2026
Summary
Replacing central atoms in molecular wires with osmium enhances electronic coupling and charge transport. This breakthrough offers new possibilities for molecular electronics and advanced materials.
Area of Science:
- Molecular electronics
- Materials science
- Supramolecular chemistry
Background:
- Tetraphenylmethane motifs are key in molecular electronics but sp3-hybridized centers hinder pi-conjugation.
- Improving electronic coupling and charge transport in molecular systems is a significant challenge.
Purpose of the Study:
- To investigate the use of tetravalent transition metals as central atoms in molecular wires.
- To enhance electronic coupling and enable bias-dependent charge transport control.
- To compare the performance of osmium(iv) based molecular wires with organic analogues.
Main Methods:
- Scanning tunnelling microscope-based break junction measurements of single-molecule conductance.
- Electrochemical and spectroscopic studies.
- First-principles calculations.
Main Results:
- Osmium(iv) complexes showed significantly reduced conductance decay with length compared to organic analogues.
- Conductance of osmium(iv) wires was electrochemically modulated up to 80x higher than silane analogues in polar media.
- Osmium(iv) wires exhibited more delocalized frontier orbitals and smaller HOMO-LUMO gaps.
Conclusions:
- Transition metal tetraaryl complexes, specifically osmium(iv), are promising building blocks for molecular circuits.
- Replacing group 14 central atoms with tetravalent transition metals enhances electronic coupling and charge transport.
- Osmium(iv) based molecular wires offer tunable and efficient charge transport properties.
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