Date of Award

Winter 2017

Project Type

Thesis

Program or Major

Biochemistry

Degree Name

Master of Science

First Advisor

Krisztina Varga

Second Advisor

Rick Cote

Third Advisor

Christine Caputo

Abstract

Chiroptical activity in cadmium selenide (CdSe) and cadmium sulfide (CdS) quantum dots (QDs) has been induced by interactions with chiral capping ligands, either with thiol functional group containing biomolecules (e.g. cysteine) or ‘thiol-free’ biomolecules (e.g. malic acid). This induced chirality is theorized to be the result of electronic orbital hybridization between the QD and ligand, not from physical distortion of crystal structure. The polarity of the resulting circular dichroism (CD) spectra shows a ‘mirror-image’ between enantiomers of the same ligand. However, it is possible for two ligands of the same absolute configuration to induce mirror-image CD spectra, as is the case for L-homocysteine and N-acetyl-L-cysteine. This is theorized to be a result of the geometric arrangement of the ligands on the surface of the QD, as predicted by non-empirical ab initio simulations. Further, the functional groups present in the ligand play a role in the induction of chiroptical activity, possibly by affecting the binding geometry or orbital hybridization of the ligand. With this and continuing work, it may be possible to predict the ligand-induced chiroptical activity of these QDs, leading to the opportunity for rational design of chiral QDs and other nanomaterial systems.

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