Research

PhotoMagnetic Switches (PMS).

The research activity of our group is focused on the development and investigation of new molecular switches, molecules that exists in two forms (states), such that one form of the molecule can be switched to another form by changing the temperature, applied pressure, irradiation with light, or other stimuli. Since molecular switches can be as small as a single molecule, they open a new era in modern nanotechnology and could play a central role in the miniaturization of processors, sensors and memory devices in the future.

The molecular switches being developed in our group are coordination compounds of late transition metals that can be controlled by light, the so called molecular photoswitches. Our primary long-term goal is to develop new types of molecular photoswitches, magnetic properties of which can be changed at single molecular level at room temperature in the solid state.

In order to achieve this goal the cooperative work in several branches of chemistry is required: Organic chemistry is used as a tool for designing new photoactive ligands. Coordination chemistry is the main instrument to construct target metal complexes. Photochemistry plays a crucial role in evaluation of the photophysical properties of new photoactive ligands and metal complexes. The properties of the switches are investigated by several spectroscopic methods including electronic absorption, Mössbauer, EPR and NMR spectroscopy as well as magnetic susceptibility measurements and electrochemisty. The development of new ligand systems and metal complexes is assisted by the predictions obtained from theoretical calculations.

 

Project 1. PMS on the base of spin-crossover metal complexes with photoactive ligands

Spin-crossover (SCO) metal complexes are among the best known classes of molecular bistable systems. Their optical, magnetic and other physicochemical properties can be switched by changing the temperature, applying pressure, or irradiation with light. Although photoswitching in SCO complexes is well documented in the light-induced excited spin state trapping (LIESST) effect discovered in middle eighties, this effect is usually operative at low temperatures T < 50 K. This imposes serious limitations for its application in genuine photodevices.

We develop novel metal complexes which will overcome the low-temperature limitations of the LIESST effect. We aim at introducing photoactive ligands to the SCO complexes in such a way that photoisomerization of the photoactive ligand will modify the ligand field. This light-driven modulation should result in a spin transition at the metal ion in SCO complexes that may be accomplished at room temperature.

 

Project 2. PMS on the base of valence-tautometic metal complexes with photoactive ligands

---soon---

 

 

Photocatalysis (future project)

 

Updated: 29.03.2011 by MMK

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