טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentZouev Irena
SubjectHomogeneous Photochemistry in the Solid State
DepartmentDepartment of Chemistry
Supervisor Professor Emeritus Menahem Kaftory
Full Thesis textFull thesis text - English Version


Abstract

Reversible solid-state and photochromic reactions have attracted considerable attention due to their potential use as a basis for optical data storage devices. Solid-state photochemical reactions are highly dependent on the geometry of the reacting compound and its product. An important advantage in the understanding of the reaction mechanism, the course of the reaction, and the reaction control factors lies in the ability to follow the geometrical changes by monitoring the reaction by X-ray diffraction measurements. In inclusion compounds, the guest molecules occupy space formed by the host molecules. If the host molecules provide topochemical conditions required for bimolecular reactions and the guest molecules are photochemically active, regio- and stereo-selective reactions are anticipated. For investigation two main types of photochemical reactions were chosen. The first type is unimolecular reactions. In this type of reaction the effect of an organized crystalline environment upon the properties of organic photochromic compounds was studied. We have designed and synthesized new photochromic inclusion compounds based on derivatives of N-salicylideneanilines and spiropyranes. The second type is bimolecular reactions. Photochemical [4 + 4] dimerization reactions of three anthracene derivative in inclusion compounds were studied. Structural changes during photoreaction were monitored using X-ray diffraction. Mutual orientation of the guest molecules and the way they are oriented within the cavities formed by the host molecules were described. The significance of this work is that it addressed issues essential to the detailed  understanding of observed interactions in molecular crystals. It also improved our ability to follow the geometrical changes during the reaction.