| dc.contributor.author | Raghunathan, Ramya | |
| dc.description.abstract | Light is an environmentally benign and renewable source of energy that finds wide application in
the field of science. This dissertation explores two areas of chemistry that utilizes light extensively viz.,
asymmetric phototransformations and photodegradation of polymers. Phototransformation is an elegant
method to construct structurally complex and diverse organic scaffolds. However, controlling the excited
state in phototransformation to manipulate its stereochemical outcome is a challenge. This dissertation
discloses a unique method employing atropisomeric chromophore to tackle asymmetric induction from the
excited state. Photodegradation is a safe method to breakdown polymers that pose huge environmental
and ecological concerns. Apart from designing polymers with a phototrigger that initiates the breakdown
in a programmed fashion, this thesis also demonstrates recovery and reuse of monomers making the
strategy sustainable.
Chapter 1 describes the importance of light and basic principles involved in organic
phototransformations. In this section, principle differences between asymmetric thermal and
photochemical transformations are introduced, methodologies developed in asymmetric
phototransformations and the role of light in medicinal/biological system and material science is
presented.
Chapter 2 evaluates metal free, thiourea/urea organocatalyst in enantioselective 6π-
photocyclization of acrylanilides. Preliminary investigations revealed that the asymmetric induction
imparted by thiourea was low. Detailed photophysical analysis provided valuable information on the
excited state interaction of the substrate with the catalyst, opening avenues for future development of this
strategy.
Chapter 3 demonstrates “axial-point chiral” strategy towards atropselective Paternò-Büchi
reactions of oxoamides and chain length dependent [2+2] vs. [5+2]-photocycloaddition of atropisomeric
maleimides. Axial chirality dictated high enantioselectivity (>97 %) in the photoproduct, while the solvent
and substitution in the reactant controlled the diastereomeric ratio in photoproducts respectively.
Chapters 4-5 report the photodegradation of bio-derived polymers using phototriggers. This
method not only enabled us to deconstruct the polymers to its functional monomer(s) but also enabled a
pathway to recover and recycle the monomer highlighting the sustainability of the strategy. In summary this thesis details the role of light in asymmetric phototransformations using
organocatalyst and atropisomeric chromophores leading to chiral photoproducts. Further, it describes the
photodegradation of biomass-derived polymers and its recoverability and reusability of the monomer as a
sustainable approach. | en_US |
| dc.publisher | North Dakota State University | en_US |
| dc.rights | NDSU Policy 190.6.2 | |
| dc.title | Photons in Action: Asymmetric Synthesis and Polymer Degradation | en_US |
| dc.type | Dissertation | en_US |
| dc.date.accessioned | 2018-04-23T18:44:15Z | |
| dc.date.available | 2018-04-23T18:44:15Z | |
| dc.date.issued | 2016 | en_US |
| dc.identifier.uri | https://hdl.handle.net/10365/28011 | |
| dc.rights.uri | https://www.ndsu.edu/fileadmin/policy/190.pdf | |
| ndsu.degree | Doctor of Philosophy (PhD) | en_US |
| ndsu.college | Science and Mathematics | en_US |
| ndsu.department | Chemistry and Biochemistry | en_US |
| ndsu.advisor | Sivaguru, Jayaraman | |
