Author's School

Graduate School of Arts & Sciences

Author's Department/Program

Chemistry

Language

English (en)

Date of Award

5-24-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Sophia Hayes

Abstract

[2+2] photocycloadditions have been the basis of study for many years, due to numerous potential applications, for example: optical switches, shape-memory polymers, and photolithography. Even though these reactions have been widely studied, there are still unanswered questions. These cycloadditions in the solid state become more complicated due to the limited movement allowed by solids. Understanding the effect this limit has on the system is necessary for understanding the photoreaction. A specific example is a single-crystal-to-single-crystal: SC to SC) transformation. Generally, materials undergo a SC to SC reaction when irradiated with light in the tail of the absorption band: "tail" irradiations) or wavelength selective irradiations. The reaction progresses differently with broadband irradiations. There are very few materials that actually can undergo a single-crystal-to-single crystal photoreaction. Cinnamic acid is one of those few materials. Two materials, α-trans-cinnamic acid and a supramolecular complex, 2(4, 4 bipyridyl ethylene) * 2(resorcinol), have been studied using tail irradiations. Partially-reacted single crystals of cinnamic acid have been examined, and the tensor of the product has been determined. Domain size experiments using spin diffusion have been performed for determining the mechanism of formation of the products under wavelength selective irradiation in cinnamic acid single crystals. The wavelength selective kinetics curve for the supramolecular complex has been determined. The crystal structure of the product has also been determined and confirmed with powder X-ray diffraction and simulations. The third material studied is a shape-memory polymer which was synthesized for the purpose of analyzing the photoreaction and the reversible crosslinking. The results of 13C CP: cross polarization) and CPMAS solid state NMR experiments will be discussed.

Comments

Permanent URL: http://dx.doi.org/10.7936/K7ZS2TJQ

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