|Ph.D Student||Lavy Tali|
|Subject||Photochemical Reactions of Inclusion Compounds in the|
|Department||Department of Chemistry||Supervisor||Professor Emeritus Menahem Kaftory|
|Full Thesis text|
An inclusion compound is composed of an inert host molecule
and reactive guest molecules. Usually the reaction occurs in a
cavity formed by the host molecule.
This work is divided into two separated projects. The first deals with  photodimeriztion of pyridon derivatives and the other deals with unimolecular photoyclization of N,N-α-oxoamids. These two projects shall be referred to henceforth as "unimolecular" and "bimolecular" projects.
The goal of the first project was to find and study systems in which the reactions are associated with a decrease in the guest volume. The questions that arise are: What happens when the volume of the product is smaller than that of the reactant molecule?
Will the unit cell collapse and the crystal be
destroyed? Will molecules from the surrounding penetrate the crystal and occupy
generated voids so that the crystalline nature is maintained?
What is the influence of hydrogen bonds on the freedom of movement of potentially reacting molecules?
We have found two inclusion compounds, each of them consist of 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol as a host molecule and 6-methyl-2-1H-pyridone or or 2-(1H)- pyridone as photosensitive guest molecule. In these inclusion compounds, the photodimerization of the guest was associated with significant, extremely unexpected rotation, without destruction of its crystal nature. Due to the dimerization, the volume of the product decreased in respect to the reactant’s volume, and consequently,
channels were formed. These channels were occupied by water molecules that penetrate the crystal from the surroundings, only at the very end stage of the conversion, in order to stabilize it. A mechanism for the manner in which the water molecules penetrate the crystal was proposed.
The goal of the second project was to study the influence of the reactant’s surrounding on the course of the reaction in the case of unimolecular reactions. Inclusion compounds in which the guest molecule are N,N-alpha-oxoamids were examined. I have found that by changing the host molecule, different surrounding environments can be achieved, which can alter the course of the reaction.