Dipole Switching by Intramolecular Electron Transfer in Single-Molecule Magnetic Complex [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄]

Area of Science:

• Molecular Magnetism
• Quantum Chemistry
• Materials Science

Background:

• Single-molecule magnets (SMMs) exhibit quantum mechanical properties at the molecular level.
• Controlling the dipole moment of SMMs is crucial for applications in molecular spintronics and quantum computing.
• Intramolecular electron transfer is a potential mechanism for dynamic manipulation of SMM properties.

Purpose of the Study:

• To investigate intramolecular electron transfer in [Mn12O12(O2CR)16(H2O)4] complexes.
• To understand the role of ligands and lattice distortions in electron transfer dynamics.
• To determine the feasibility of switching the molecular dipole moment via controlled electron transfer.

Main Methods:

• Density Functional Theory (DFT) with onsite Coulomb energy correction (DFT + U) was employed for energetic calculations.
• Analysis of lattice distortions and their impact on electron localization.
• Computational modeling of electron transfer pathways, including superexchange-mediated tunneling.

Main Results:

• Lattice distortions are essential for stabilizing localized electron states on the outer ring of the Mn12 complex.
• The lowest-energy electron transfer pathway involves superexchange-mediated tunneling through the complex's center.
• Energy barriers for charge transfer range from 0.4 to 54 meV, depending on ligand substitution and isomer.
• Reversing the molecular dipole moment requires an electric field strength of 0.01–0.04 V/Å.

Conclusions:

• Intramolecular electron transfer is a viable mechanism for switching the dipole moment of Mn12 SMMs.
• Ligand choice and structural flexibility significantly influence the energetics and feasibility of dipole switching.
• The study provides a computational framework for designing SMMs with tunable dipole moments for advanced applications.