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Publication Date

2018-11-29

Availability

UM campus only

Embargo Period

2018-11-29

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2018-11-02

First Committee Member

Angel E. Kaifer

Second Committee Member

Françisco M. Raymo

Third Committee Member

Jamie D. Walls

Fourth Committee Member

Sharon T. Zane

Abstract

This dissertation investigates supramolecular complexation studies between various electroactive guests and the receptors cucurbit[7]uril and/or cucurbit[8]uril as well as anion recognition studies with a cationic guest. The investigation of these systems have been carried out by a wide range of techniques including nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), density functional theory (DTF) computational calculations, electrochemical studies including cyclic voltammetry (CV) and square wave voltammetry (SWV) and ultraviolet–visible spectrophotometry (UV–Vis). Chapter 1 is an introduction to the fundamentals of supramolecular chemistry as well as a brief summary of cucurbit[n]urils (CB[n]s), the host molecules studied in this dissertation, including their synthesis, structural properties and binding behaviors. It also includes a relevant collection of scholarly work done by others on the two types of redox- active guests studied in this dissertation — ferrocenyl and viologen derivatives. Chapter 2 discusses the 1:1 binding interactions between a ferrocene derivative, ferrocenylguanidinium, containing a delocalized positive charge and the hosts cucurbit[7]uril and cucurbit[8]uril. While cationic and neutral ferrocene derivatives have been investigated with these hosts, we studied ferrocenylguanidinium as an intermediate because its positive charge is delocalized and not “fixed” as other cationic ferrocene guests. Chapter 3 presents a novel ferrocene derivative, ferrocene amino acid and its reversible, pH controlled association and dissociation complexation with cucurbit[7]uril. While various supramolecular systems controlled by external stimuli have been investigated, the controlled uptake and release of the guest is rare. Ferrocene amino acid has three different protonated forms, each with a different affinity towards cucurbit[7]uril. Chapter 4 describes the synthesis of various bis(viologen) derivatives and their binding interactions towards cucurbit[7]uril. These axle-type guests composed of two viologen units lead to pseudorotaxane complexes containing one and two cucurbit[7]uril hosts. Our main goal here was to investigate the effect of vastly different terminal groups and the effect of the length of the methylene chain connecting the two viologen units on the complexation with cucurbit[7]uril. Chapter 5 is a brief summary of electrochemical anion recognition studies between ferrocenylguanidinium and various tetrabutylammonium salt anions. Ferrocenylguanidinium combines the redox active ferrocene center with the delocalized positive charge and other structural features that allow the organometallic receptor to potentially bind and sense anionic guests electrochemically. Chapter 6 proposes the design and synthesis of a pH sensitive guest, p-bis-(8- hydroxyquinoline-methyl)benzene bromide, and its binding interactions with cucurbit[7]uril and cucurbit[8]uril. This guest contains an aromatic unit sandwiched between two pH-dependent hydroxyquinoline units. Our aim was to investigate the formation of a negative charge in close proximity to a positive charge on the binding between the two hosts.

Keywords

Cucurbituril; Supramolecular chemistry; Electrochemistry; Ferrocene; Viologen; CBn

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