Weaving, Rotating and Threading: Novel Self Assembly and Controlled Molecular Motion

  • Stephen Fielden

Student thesis: Phd


Self assembly is the process whereby the interactions between individual molecular components affect association to generate more complex organised structures. Supramolecular chemists have studied such behaviour since the 1960s. Nature has mastered self assembly: living organisms consist of hierarchal structures (organs, cells, organelles) whose formation and persistence rely on programmed self assembly processes. Life is however not a static phenomenon; it is a dynamic set of evolving processes. Therefore, as first discussed by Erwin Schroedinger in 1944, life operates far from thermodynamic equilibrium. This is only possible if molecular motion can be restricted and thus controlled. Here we present new synthetic methods of self assembly and controlled molecular motion, which may prove useful in the production of nanotechnology that may eventually be capable of showing life-like properties. Chapter One contains an introduction to molecular knots. An overview of synthetic strategies, the theory of knotting and applications of molecular knots is given. Chapter Two presents the self assembly of a 3 x 3 interwoven grid and its subsequent covalent capture by olefin metathesis to produce a molecular endless knot. Chapter Three details the synthesis and operation of three molecular motors that utilise an energy ratchet mechanism. Chemically fueled unidirectional linear and rotary motion is achieved using trichloroacetic acid. Chapter Four comprises a further study of the chemically fueled operation of a molecular motor based on a [2]catenane architecture. Chapter Five describes the spontaneous self assembly of [2]rotaxanes by performing N-alkylation, aza-Michael addition and N-acylation in the presence of crown ether macrocycles. Chapter Six consists of a detailed study into the improved self assembly of rotaxanes using N-acylation and similar reactions with 24-crown-8.
Date of Award1 Aug 2020
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorDavid Leigh (Supervisor) & Michael Greaney (Supervisor)


  • Catenanes
  • Supramolecular Chemistry
  • Rotaxanes
  • Molecular Knots
  • Molecular Machines
  • Self Assembly

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