Single-Molecule Spin Switch Based on Voltage-Triggered Distortion of the Coordination Sphere

Area of Science:

• Molecular Electronics
• Coordination Chemistry
• Spin Crossover Materials

Background:

• Single-molecule electronics offer potential for miniaturized devices.
• Controlling molecular properties with external stimuli is crucial for device functionality.
• Iron(II) spin crossover complexes are known for their switchable magnetic properties.

Purpose of the Study:

• To introduce a new single-molecule-switching concept.
• To investigate the electric field-induced spin state switching of iron(II) complexes.
• To correlate molecular design with switching behavior in electronic junctions.

Main Methods:

• Synthesis of heteroleptic iron(II) complexes with varying dipole moments.
• Investigation of charge transport properties using mechanically controlled break-junction techniques.
• Statistical analysis of voltage-dependent bistability in molecular junctions.

Main Results:

• Demonstrated a novel single-molecule-switching mechanism based on electric field-induced distortion of the iron(II) coordination sphere.
• Observed voltage-dependent bistability in molecular junctions, which increased with the intrinsic dipole moment of the iron(II) complexes.
• Identified a constant threshold electric field required for switching, supporting the proposed mechanism.

Conclusions:

• The study presents a viable single-molecule-switching concept utilizing coordination-sphere-dependent spin states of iron(II) complexes.
• The findings highlight the potential of designing molecular switches by tuning dipole moments and exploiting electric field effects.
• This work paves the way for developing novel molecular electronic devices with tunable functionalities.