The University of Southampton
University of Southampton Institutional Repository

Exploitation of noncovalent/dynamic covalent interactions in sensing, self-assembly and membrane transport

Exploitation of noncovalent/dynamic covalent interactions in sensing, self-assembly and membrane transport
Exploitation of noncovalent/dynamic covalent interactions in sensing, self-assembly and membrane transport
This thesis reports the development of several novel chemical sensing systems, self-assembled aggregates, and membrane transporters in which noncovalent and/or dynamic covalent interactions operate.

Perylenebisimide dyes functionalized with boronic acid groups were designed as effective chirality sensors for [alpha]-hydroxy carboxylates. Binding of chiral ?-hydroxy carboxylate guests via boronate ester linkage leads to formation of optically active helical stacks of perylenebisimide dyes in water, giving diagnostic induced circular dichroism signals in the perylene absorption region.

A boronic acid-functionalized pyrene fluorophore forms excimer-emissive stacks upon cooperative binding of fluoride ion and catechol to the boron centre, allowing sensitive sensing of fluoride at ppm levels in aqueous solution which was unprecedented for boronic acids. The stabilization of boron-fluoride adduct in the aggregate and increase of Lewis acidity via catechol binding were proposed responsible for the unprecedented affinity, as supported by control experiments.

A dynamic covalent amphiphile comprised of 4-formylphenylboronic acid and octylamine forms vesicular aggregates selectively with glucose which can bind two boronic acids thus forming “Gemini-type” amphiphiles. The aggregates feature stabilization of imine bond and boronate ester linkage, with the two dynamic covalent bonds working in synergy promoting the formation of each other despite the spatial separation. The system allows selective sensing of glucose against the interference of fructose, for the first time without resorting to any synthesis.

A dynamic covalent approach was employed to transmembrane transport of amino acids by the formation of a three-component assembly. A mixture of a squaramide and a lipophilic and electrophilic aldehyde is shown to synergistically transport glycine across phospholipid vesicle membranes. The transport is proposed to occur via a hydrogen-bonded anionic glycine hemiaminal/imine, with control experiments supporting the role of hemiaminal/imine in the observed facilitated glycine transport

Finally, the issue of electrogenic/electroneutral transport mechanisms and potential proton or hydroxide transport for synthetic anionophores were examined. It is shown that depending on acidity, many synthetic anionophores can facilitate electrogenic proton or hydroxide transport. However, two newly-developed small molecules are shown to promote chloride transport without significant proton/hydroxide transport (pH gradient dissipation) at low concentrations, essentially mimicking the electrogenic cationophore valinomycin. The chloride > proton/hydroxide selective anionophores feature encapsulation of chloride ion via weak hydrogen or halogen bonds.
Wu, Xin
65360fe8-d25a-4652-b7e4-40d513b57e7e
Wu, Xin
65360fe8-d25a-4652-b7e4-40d513b57e7e
Gale, Philip
c840b7e9-6847-4843-91af-fa0f8563d943

(2016) Exploitation of noncovalent/dynamic covalent interactions in sensing, self-assembly and membrane transport. University of Southampton, Faculty of Natural and Environmental Sciences, Doctoral Thesis, 308pp.

Record type: Thesis (Doctoral)

Abstract

This thesis reports the development of several novel chemical sensing systems, self-assembled aggregates, and membrane transporters in which noncovalent and/or dynamic covalent interactions operate.

Perylenebisimide dyes functionalized with boronic acid groups were designed as effective chirality sensors for [alpha]-hydroxy carboxylates. Binding of chiral ?-hydroxy carboxylate guests via boronate ester linkage leads to formation of optically active helical stacks of perylenebisimide dyes in water, giving diagnostic induced circular dichroism signals in the perylene absorption region.

A boronic acid-functionalized pyrene fluorophore forms excimer-emissive stacks upon cooperative binding of fluoride ion and catechol to the boron centre, allowing sensitive sensing of fluoride at ppm levels in aqueous solution which was unprecedented for boronic acids. The stabilization of boron-fluoride adduct in the aggregate and increase of Lewis acidity via catechol binding were proposed responsible for the unprecedented affinity, as supported by control experiments.

A dynamic covalent amphiphile comprised of 4-formylphenylboronic acid and octylamine forms vesicular aggregates selectively with glucose which can bind two boronic acids thus forming “Gemini-type” amphiphiles. The aggregates feature stabilization of imine bond and boronate ester linkage, with the two dynamic covalent bonds working in synergy promoting the formation of each other despite the spatial separation. The system allows selective sensing of glucose against the interference of fructose, for the first time without resorting to any synthesis.

A dynamic covalent approach was employed to transmembrane transport of amino acids by the formation of a three-component assembly. A mixture of a squaramide and a lipophilic and electrophilic aldehyde is shown to synergistically transport glycine across phospholipid vesicle membranes. The transport is proposed to occur via a hydrogen-bonded anionic glycine hemiaminal/imine, with control experiments supporting the role of hemiaminal/imine in the observed facilitated glycine transport

Finally, the issue of electrogenic/electroneutral transport mechanisms and potential proton or hydroxide transport for synthetic anionophores were examined. It is shown that depending on acidity, many synthetic anionophores can facilitate electrogenic proton or hydroxide transport. However, two newly-developed small molecules are shown to promote chloride transport without significant proton/hydroxide transport (pH gradient dissipation) at low concentrations, essentially mimicking the electrogenic cationophore valinomycin. The chloride > proton/hydroxide selective anionophores feature encapsulation of chloride ion via weak hydrogen or halogen bonds.

PDF
Final thesis 25777548 Xin Wu.pdf - Other
Download (19MB)

More information

Published date: 31 May 2016
Organisations: University of Southampton, Chemistry

Identifiers

Local EPrints ID: 398005
URI: http://eprints.soton.ac.uk/id/eprint/398005
PURE UUID: 52cd0cc9-1864-4297-bb7c-f17778f600aa
ORCID for Philip Gale: ORCID iD orcid.org/0000-0001-9751-4910

Catalogue record

Date deposited: 15 Jul 2016 13:06
Last modified: 23 Jun 2019 04:01

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×