Systems with switchable domains on the molecular or supramolecular level on a nanoscopic or mesoscopic scale. One goal is to enable a highly efficient information storage and conductor. Towards this end, a promising and challenging field is the study of compounds with electronic multistability. A considerable interest is devoted to materials containing transition metals and exhibiting appealing properties of molecular bistability.

• 1964 TISC
• 1970 PISC
• 1984 LIESST
• 1998 LITH
• 1999 LiPTH
• 2000 SF-LIESST
• 2000 AIMS

Size, Shape and PES selective detection of molecules from the gas phase, such as an atmosphere of a planet.

• for the next NASA mars mission in 2003 (Athena rover).
• industrial application
  • New Molecular Sensors allow to use the Moessbauer Effect as Hygrometer
    F. Renz, P.A. de Souza Jr., G. Klingelhöfer, H.A. Goodwin, P. Gütlich
    ISIAME, Book of Abstracts, Norfolk, Virginia, USA, 13.-18.8.2000.
    
  • Molecular Sensors for Terrestrial and Extraterrestrial Application
    F. Renz, P.A. de Souza Jr., G. Klingelhöfer, H.A. Goodwin, P. Gütlich
    ICMM, San Antonio, Texas, USA, 2000.

(supramolecular optically switchable transition-metal-complexes; discovered in 1999)

• Photophysics, Photochemistry
• Optical storage and switch
  
  
  • F. Renz, P. Gütlich, H. Spiering,
    German Patent Application 1999, Aktz. 199 46 646 7
    
    
  • Strong Field Iron(II) Complex Converted by Light into a Long-Lived High-Spin State
    F. Renz,H. Oshio, V. Ksenofontov, M. Waldeck, H. Spiering, P. Gütlich,
    Angew. Chem. Int. Ed. 2000, 39, No. 20, 3699-3700

(optically switchable transition-metal-complexes)

• Photophysics, Photochemistry
• Optical storage and molecular switching at room temperature
  
  • LIGHT PERTURBED HYSTERESIS IN AN IRON(II) SPIN-CROSSOVER COMPOUND OBSERVED BY THE MÖSSBAUER EFFECT
    F. Renz, H. Spiering, H. A. Goodwin, P. Gütlich
    Int. Conf. on the Application of the Moessbauer Effect (ICAME 99) , Garmisch Partenkirchen, Germany, 29.8-3.9.1999.

  
  
  

  • LIESST, LITH, AND LiPTH IN [FeL](BF4)2 COMPLEXES
    (L = Hexa(ptz), Bis(phy))
    F. Renz, H. Spiering, P.-M. Anglade, H. A. Goodwin, P. Gütlich
    TOSS, Leiden, Netherlands, 2000.

• Light-perturbed hysteresis in an iron(II) spin-crossover compound observed by the Moessbauer effect
  F. Renz, H. Spiering, H.A.Goodwin, P. Gütlich
  Hyperfine Interactions 2000, 126, 155-158

(thermally switchable transition-metal-complexes; discovered in iron(ii) componds in 1964) Transition between a Low Spin and a High Spin State in Solid and Liquid State

• Influenced by:
  • Ligand
  • Anion
  • Crystallsolvents
  • Formation of mixed crystals
  • Isotope-effekt
  • Pressure
  • Magnetic fields

• Sensors
• Theoretical Models

(pressure induced switchable transition-metal-complexes;
discovered in iron(ii) compounds around 1970)
Transition between a Low Spin and a High Spin State in Solid and Liquid State

• Influenced by:
  • Ligand
  • Anion
  • Crystallsolvents
  • Formation of mixed crystals
  • Isotope-effekt
  • Pressure
  • Magnetic fields

• Sensors

(optically switschable transition-metal-complexes; discovered in iron(II) in 1984)

• Photophysics, Photochemistry
  • X-RAY STUDY OF THE LIGHT-INDUCED META-STABLE STATES OF A SPIN CROSSOVER COMPOUND
    J. Kusz, F. Renz, H. Spiering, P. Gütlich.
    TOSS, Leiden, Netherlands, 2000.
  • LIESST, LITH, AND LiPTH IN [FeL](BF4)2 COMPLEXES
    (L = Hexa(ptz), Bis(phy))
    F. Renz, H. Spiering, P.-M. Anglade, H. A. Goodwin, P. Gütlich
    TOSS, Leiden, Netherlands, 2000.

• Optical storage and switch
• Kinetics of relaxation
• Photorefractive properties

(optically switschable transition-metal-complexes)

• Photophysics, Photochemistry
• Optical storage and switch
  • LIESST, LITH, AND LiPTH IN [FeL](BF4)2 COMPLEXES
    (L = Hexa(ptz), Bis(phy))
    F. Renz, H. Spiering, P.-M. Anglade, H. A. Goodwin, P. Gütlich
    TOSS, Leiden, Netherlands, 2000.

• Electronic states
• Optical and magnetical properties of transition-metal-complexes

Binuclear transition-metal-complexes

• Paramagnetic to antiferromagnetic-coupled transition (pressure, light)
• DIRECT MONITORING OF SPIN STATE AND MAGNETIC COUPLING IN BINUCLEAR COMPOUNDS
  Vadim Ksenofontov, Hartmut Spiering, Franz Renz, Ana B. Gaspar, Jose Antonio Real and Philipp Gütlich
  TOSS, Leiden, Netherlands, 2000.
• LITH-effect
• LiPTH-effect

• Valence-fluctuation