Valence Tautomeric Molecular Switches

Similarly to spin-crossover metal complexes, valence tautomeric (VT) metal complexes offer great opportunity to control their magnetic and other physicochemical properties by external stimuli. The switching of the electronic structure and associated properties in VT systems with light is difficult to achieve: temperatures below 20 K are generally required to stabilize photoinduced states.

By introducing efficient and robust organic photochromes into VT complexes we create “smart” molecular systems that allow controlling the spin and oxidation state of coordinated metal ions and thus the associated magnetic properties of materials with light at room temperature. Similarly to spin-crossover molecular switches, the reversibility of photoswitching process can be utilized to design rewritable memories, whereas the addressing of spin and oxidation states at the single molecule level can lead to the development of ultrahigh-density memory units.

Thus, valence tautomeric metal complexes were switched chemically at room temperature, which allows a previously unknown control of magnetic properties of solutions. A new concept “Coordination-Induced Valence Tautomerism” (CIVT) was introduced to molecular magnetism.

 

We switched valence tautomeric metal complexes with light at room temperature for the very first time, which allows a unique control of magnetic properties of solutions. A new concept “Ligand-Driven Light-Induced Valence Tautomerism” (LD-LIVT) was introduced to the field of molecular magnetism.

Publications:

Low-spin to low-spin valence tautomeric transition in cobalt bis-dioxolenes.
M. Mörtel, J. Oschwald, A. Scheurer, T. Drewello, M. M. Khusniyarov,
Dalton Trans. 2024, 53, 4098. link

Molecular Valence Tautomeric Metal Complexes for Chemosensing.
M. Mörtel, J. Oschwald, A. Scheurer, T. Drewello, M. M. Khusniyarov,
Inorg. Chem. 2021, 60, 14230–14237. link

Bidirectional Photoswitching of Magnetic Properties at Room Temperature: Ligand-Driven Light-Induced Valence Tautomerism.
A. Witt, F. W. Heinemann, M. M. Khusniyarov,
Chem. Sci. 2015, 6, 4599–4609. link

Modulation of Magnetic Properties at Room Temperature: Coordination-Induced Valence Tautomerism in a Cobalt Dioxolene Complex.
A. Witt, F. W. Heinemann, S. Sproules, M. M. Khusniyarov,
Chem. Eur. J. 2014, 20, 11149–11162. link