Selective photo-transformations in confined media
Description
The dissertation concentrates on the role of confined media in achieving selectivity in photoreactions and the use of theoretical calculations to understand and gain insight into the experimental observations Chapter 1 presents the concept of selectivity and the role of confined media in achieving transformation in an organized environment. The chapter highlights a general introduction about the structure and properties of zeolites Chapter 2 presents the concept of control of the direction of photoisomerization diphenylcyclopropane derivatives. Ab initio computations on cation binding to reactant have been very valuable in rationalizing the observed photochemical behavior of diphenylcyclopropane derivatives included in zeolites Chapter 3 presents the use of zeolites in chiral photochemistry. Asymmetric photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives was used as a probe reaction. Chiral inductors are adsorbed onto the zeolite to render it chiral. Moderate enantioselectivities have been achieved for the photoisomerization processes Chapter 4 presents the use of zeolites to carry out asymmetric phototransformation of 2,3-diphenylcyclopropane-1-carboxylic acid linked covalently to the various chiral auxiliaries. High asymmetric induction ensues due to the close interaction that develops between the chiral auxiliary and the reactant facilitated by the cations Chapter 5 explores the use of zeolites to carry out asymmetric photoisomerization of 2,3-diphenyl-1-benzoylcyclopropane derivatives that are structurally similar to 2,3-diphenylcyclopropane-1-carboxylic acid derivatives. Both the chiral inductor and the chiral auxiliary methodology were investigated Chapter 6 presents the use of zeolites in triplet sensitized asymmetric photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives Chapter 7 investigates the photophysics of diphenylcyclopropane derivatives. Based on photophysical studies it has been shown that diphenylcyclopropane derivatives undergo the less common adiabatic reaction at 77K and emit from the excited 1,3-diradical intermediate Chapter 8 investigates the mechanistic intricacies of photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives and 2,3-diphenyl-1-benzoylcyclopropane derivatives Chapter 9 describes the use of zeolites in achieving regioselectivity in the singlet oxygen mediated photooxidation. Alkenes were chosen for the purpose of study and thionine adsorbed Y zeolites was used as the sensitizer/medium. (Abstract shortened by UMI.)