Out-of-equilibrium replication and the amplification of chirality

Thesis

This thesis explores physical autocatalysis, or the replication of supramolecular aggregates of surfactants such as micelles. There is a focus on the out-of-equilibrium and non-linear behaviours that can be extracted from a process of physical autocatalysis and which characterise lifelike dynamics and properties.

Chapter 2 describes a study of reversibly-formed surfactants which form micelles within a dynamic combinatorial library. Though the system does not demonstrate a process of replication, the study of surfactants containing reversibly-formed bonds is of use towards the design of an out-of-equilibrium replicator. Thus, Chapter 3 describes the development of a physical replicator constructed by thiol-disulfide exchange which can persist, out-of-equilibrium, by the consumption of a chemical fuel, mimicking dissipative biological structures.

The second half of this thesis introduces an ambitious design for a process of physical autocatalysis with amplification of chirality. Chapters 5 and 6 detail two experimental attempts. Chapter 5 describes the study of a chiral surfactant constructed by a native chemical ligation reaction, which shows interesting differences in reactivity between homogeneous and biphasic reaction conditions. However, a process of replication is not observed, nor the amplification of chirality. A more successful system is the study in Chapter 6 on the formation of a chiral surfactant based on the autocatalytic reaction studied in Chapter 3. An interesting sense of asymmetry is established; the chiral surfactant appears to be autocatalytic and partitions into a precipitate of enhanced ee and a solution phase of diminished ee.

Authors: Morrow, SM

• DOI: 10.5287/ora-gadzbmxby
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Systems chemistry; Out-of-equilibrium
• Subjects: Chemistry, Organic