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Molecular photoconductor with simultaneously photocontrollable localized spins
Toshio Naito1, Tomoaki Karasudani, Shigeki Mori
1Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan. tnaito@ehime-u.ac.jp
Journal of the American Chemical Society
|September 6, 2012
Summary
UV light transforms an insulating crystal into a magnetic conductor by triggering a reversible photochemical reaction. This process creates photocurrents and localized spins, demonstrating optical control over material properties.
Area of Science:
- Materials Science
- Solid-State Physics
- Photochemistry
Background:
- Molecular crystals offer tunable electronic properties.
- Controlling conductivity and magnetism in materials is a key research area.
- Photochemical reactions can induce significant changes in material states.
Purpose of the Study:
- To investigate the photoinduced reversible switching of a molecular crystal's electronic and magnetic properties.
- To explore the mechanism behind the transformation from a nonmagnetic insulator to a magnetic conductor.
- To understand the role of charge transfer transitions in photoconductivity and photomagnetism.
Main Methods:
- Synthesis and characterization of the BPY[Ni(dmit)(2)](2) molecular crystal.
- UV irradiation experiments to induce and observe property changes.
- Photocurrent measurements to quantify conductivity changes.
- Electron spin resonance (ESR) spectroscopy to detect localized spins.
Main Results:
- UV irradiation reversibly converts the insulating, nonmagnetic BPY[Ni(dmit)(2)](2) crystal into a magnetic conductor.
- A significant increase in conductivity (1 order of magnitude) and the generation of localized spins were observed under UV light.
- The observed phenomena are attributed to a photochemical redox reaction and charge transfer transitions.
- The material exhibits reversible optical control, switching between an ionic salt and a charge-transfer complex state.
Conclusions:
- BPY[Ni(dmit)(2)](2) is a novel material exhibiting reversible photoswitching between insulating and magnetic conductive states.
- Photoconductivity and photomagnetism are driven by UV-induced charge transfer and redox reactions.
- This work demonstrates a pathway for optically controlling the electronic and magnetic properties of molecular materials.
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