Strategies to Control the Redox Activity of Quantum Dots through their Surface Chemistry

Perez, Kaitlyn

doi:https://doi.org/10.21985/n2-daem-mb21

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Strategies to Control the Redox Activity of Quantum Dots through their Surface Chemistry

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This dissertation describes the study of photoinduced charge transfer between QDs and molecular acceptors as a probe of the defects within ligand shells of QDs and as means to photocatalyze redox reactions. For charge transfer reactions to occur between QDs and molecules in bulk solution, the molecules must interact with the inorganic core of QDs, either by transiently colliding with or being chemically associated with the surface. Thus, this surface of QDs, which includes their ligand layer, acts an interface between the inorganic core of QDs and bulk solution. Defects within their ligand shell enable freely diffusing molecular photooxidants to corrode QDs. This research explores the mechanisms by which a series of alkythiolate ligands with varying degrees of fluorination imparts protection upon three sizes of PbS QDs from oxidation by duroquinone. The most-highly fluorinated alkythiolate ligands are most effective at passivating the surfaces of PbS QDs due to the steric bulk of their fluorinated segments; these ligands are more protective for the largest QDs than the smaller sizes because the defects present in the ligand shells of QDs are size-dependent. While the ligand shell of QDs can be instrumental in inhibiting detrimental interactions, their surface chemistry can also be exploited to enhance desirable reactivity. This research explores the kinetics and scope of the reductive photodeprotection of sulfonyl protected phenols by copper indium sulfide QDs. The rate of deprotection for a substrate that contains a known QD-binding group is significantly enhanced due to the formation of a donor-acceptor complex. The research described in this dissertation furthers the understanding of the relationship between the surface chemistry of QDs and their reactivity.

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