Community Research and Development Information Service - CORDIS

Optically triggered switches

Novel schemes are being developed for optically switchable molecular devices with controllable stability and adjustable spectral response. Photoinduced proton transfer as well as electrocyclic ring closure reactions are the underlying molecular processes used to induce the required material changes. The control of these processes is optimized via the chemical synthesis of adapted molecular structures embedded in suitable host materials.

Chemical modification of known chromophoric systems was used to adapt the spectral response and to control the relative stabilities of the two states of the molecular systems. For photochromic proton transfer systems in fluid solutions the lifetime of the metastable state could be adjusted over many orders of magnitude from less than milliseconds to more than seconds. In solid state environments the lifetime can be extended to days or more. The spectral response of photochromic diarylethene compounds was modified, making the switching possible by irradiation with new diodes emitting in the blue.

Hole burning mechanisms and the thermal stability of hole burning systems were established in polymers and crystalline model systems. In doped benzoic acid crystals the rates and ranges of photoinduced proton displacements were characterized and reaction mechanisms in these restricted environments were established. In dye doped polymers the relative importance of the physical properties of the host and guest were characterized.

Novel guest host systems suitable for hole burning applications were discovered, in particular proton transfer dyes operating in the red spectral range and suitable for semiconductor applications.mentat

Reported by

Universite Joseph Fourier-Grenoble I
BP 87
38402 Saint Martin d'Heres
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