Optically Triggered Proton and Ion Switches


PROTIOS - 7238

Work Area: Novel Concepts and New Materials for Optical Devices / All-Optical Computing

Keywords IT organics, optical data processing, controlled proton and ion transfer processes, optimised optical switches


Start Date: 27 May 92 / Duration: 36 months / Status: running

[ participants / contact ]


Abstract PROTIOS aims to lay the basis of novel schemes for optically switchable molecular devices having controllable stability. Photoinduced proton and ion transfers are the underlying molecular processes, that will be used to induce the required material changes. The control of these processes will be optimised via the chemical synthesis of adapted molecular structures embedded in suitable host materials.


Aims

All optical data processing and storage requires materials with properties that can be altered and controlled with optical fields. Major issues concern the magnitude and the kinetics of the material response. Organics offer the potential to realise suitable materials using the response on a molecular level to trigger large amplitude changes of the material via the subsequent response of supramolecular structures. The aim of PROTIOS is to establish and to demonstrate new principles allowing to control optically induced proton and ion transfer processes in molecular systems. Controlling these optical switching processes allows to develop materials where the trade-off between speed of response, stability, and magnitude of response can be adapted.

Approach and Methods

The strategy used to design and to develop novel photoactive materials is to combine molecules having known photoinduced state changes leading to a change of their proton or ion binding affinity with suitable supramolecular receptor cages. These functional entities are immobilised in polymer host materials designed to meet the requirements of providing an environment which permits the operation of the functional entity and of exhibiting good optical and mechanical properties.

The consortium brings together the human skills and forefront experimental techniques and facilities required to attain the set objectives. The project will use the interdisciplinary collaboration of synthetic chemists (Strasbourg), polymer chemists (Coimbra), and physicists (Bayreuth and Grenoble) with complementary diagnostic facilities to characterise materials under extreme conditions via high resolved time and frequency spectroscopy as well as via optical imaging and holography.

Progress and Results

For two known chromophoric proton transfer systems, chemical modifications were introduced aimed at stabilising the proton transferred state and reducing the rate of the back reaction. The proton transferred state has a higher ground state proton donor potential so that a subsequent transfer and further stabilisation of the proton can be envisioned. In some cases the stabilisation seems sufficient so that fine tuning of the relative stabilities of the tautomeric structures can be achieved by environmental forces.

Holeburning mechanisms and the thermal stability of holeburning systems were established in polymers and crystalline model systems. In crystals of benzoic acid the rates and ranges of photoinduced proton displacements were characterised 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 characterised.

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

Potential

The principles that will be explored and established in this project constitute the basic requirement for the development of novel materials suitable in a number of applications of optical data handling and processing. These applications range from archival storage and patternable guided optical structures to 2-D optical processing, where in particular, materials with extremely high third order nonlinear responses are required while a somewhat slower response is tolerable.

Latest Publications

Information Dissemination Activies

Presentations at national and international conferences (ca. 15 in 1992/93); participation in working groups defining research strategies (In France: OFTA, ULTIMATECH).


Coordinator

Université Joseph Fourier-Grenoble I - F
Laboratoire de Spectrometrie Physique
B.P. 87
F - 38402 SAINT-MARTIN D'HYERES CEDEX

Partners

Universität Bayreuth - D
Université Louis Pasteur Strasbourg - F
ICTPOL (Instituto de Cienca e Technologia de Polimeros) - P

CONTACT POINT

Prof. H.P. Trommsdorff
tel +33/76 51 47 81
fax +33/76 51 45 44
e-mail: trommsdo@grenet.fr


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PROTIOS - 7238, August 1994


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html version of synopsis by Nick Cook