Distal hydrogen-bonding effects and cofacial bimetallic salen architectures for oxygen activation chemistry
Name
181336362-MIT.pdf
Description
Full printable version
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35.67 MB
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Checksum (MD5)
11e73d4203a14928e68ea3483355f7a7
Author(s)
Yang, Jenny Yue-fon
Advisor(s)
Daniel G. Nocera.
Date Issued
2007
Publisher
Massachusetts Institute of Technology
Abstract
Two distinct structural scaffolds elaborated from Schiff-base macrocycles were designed to study the proton-coupled electron transfer chemistry of 0-0 bond forming and activation chemistry. The "Hangman" architecture is composed of hydrogen-bonding functionalities poised over a redox active manganese salophen or salen platform. The complexes proved to be proficient catalase mimics (disproportionation of hydrogen peroxide to water and oxygen). Detailed spectroscopic, computational, and structure-function relationship studies elucidated the key redox, steric, and secondary coordination sphere effects for optimal catalytic ability. The incorporation a chiral backbone into the macrocycle led to catalysts that perform enantioselective epoxidation of unfunctionalized olefins. A macrocycle with an amide, imine, and bisphenolic functionalities was also incorporated as the redox platform in the Hangman framework; the manganese complex also performed catalytic oxygen atom transfer to olefins. The second framework, dubbed "Pacman", is composed of two salen platforms linked cofacially by rigid pillars xanthene or dibenzofuran. A series of bimetallic complexes, including chromium, iron, manganese, cobalt, copper, and zinc were generated. Mossbauer spectroscopy was used in the characterization of the iron salen complexes, which were also examined for photolytic oxidation chemistry.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.
Vita.
Includes bibliographical references.
Subjects
Chemistry.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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