Dr Stephen D.P. Fielden PhD, MChem

Stephen Fielden

School of Chemistry
Leverhulme Early Career Fellow

Contact details

University of Birmingham
B15 2TT

Stephen Fielden is a Leverhulme Early Career Fellow based in the School of Chemistry.

Stephen is a researcher in functional nanotechnology and has published several research papers in this area during his PhD and postdoctoral studies. He has been awarded a fellowship from the Leverhulme Trust to undertake independent research and broaden his expertise in this area.

Nanotechnology is important to everyone’s lives and will continue to serve a vital role in solving society’s problems. As such, Stephen has given talks and been involved with outreach activities relating to nanotechnology in recent years.


  • PhD in Organic Chemistry, University of Manchester, 2019
  • MChem Chemistry, University of Oxford, 2015


Stephen Fielden qualified with a MChem in Chemistry from the University of Oxford in 2015. During this time he held a Scholarship at Hertford College. He then undertook his PhD in the group of Prof. David Leigh FRS at the University of Manchester, graduating in 2019. He was awarded the 2019 Thesis Prize from the RSC MASC group. The focus of his PhD research was the development of new artificial molecular machinery, such as motors and pumps, as well as the synthesis of rotaxanes, catenanes and knots.

After a short period as a postdoctoral research associate in Prof. Leigh’s group, Stephen moved in 2021 to Prof. Rachel O’Reilly’s group at the University of Birmingham, a world leader in polymer nanotechnology research. Stephen was subsequently awarded a Leverhulme Early Career Fellowship, that will allow him to continue his research into functional polymer nanotechnology whilst working towards research independence.

Postgraduate supervision

Stephen co-supervises PhD students with Professor Rachel O’Reilly.


Molecular Machines

Stephen has researched the development and operation of molecular Brownian ratchet mechanisms. These allow the construction of molecular machines which can drive systems away from thermodynamic equilibrium. Stephen has demonstrated prototypical molecular machines formed of interlocked molecules, including catenanes and rotaxanes. He has focussed on chemically fuelled systems, which can operate using the energy released by the degradation of high energy chemicals to waste products.

Polymer Nanotechnology

Stephen’s research interests have recently branched into the use of polymers to construct functional nanotechnology. Stephen is currently exploring the use of amphiphilic block co-polymers to produce nanoparticles that react to different stimuli. Such dynamic behaviour will be used to control the outcome of chemical reactions.

Stephen has expertise in organic synthesis, NMR, mass spectrometry, electron microscopy and light scattering.


  1. 1.    Amano, S., Fielden, S. D. P., Leigh. D. A. (2021), A Catalysis-Driven Artificial Molecular Pump. Nature, 594: 529–534.
  2. Leigh, D. A., Danon, J. J, Fielden, S. D. P., Lemonnier, J.-F., Whitehead, G. F. S., Woltering, S. L. (2021) A Molecular Endless (74) Knot. Nature Chemistry, 13: 117–122.
  3. Tian, C., Fielden, S. D. P., Whitehead, G. F. S., Vitorica-Yrezabal, I. J., Leigh, D. A. (2020) Weak functional group interactions revealed through metal-free active template rotaxane synthesis. Nature Communications, 11: 744.
  4. Biagini, C., Fielden, S. D. P., Leigh, D. A., Schaufelberger, F., Di Stefano, S., Thomas, D. (2019) Dissipative Catalysis with a Molecular Machine.  Angewandte Chemie International Edition 58: 9876–9880. Hot paper. Featured on cover.
  5. Erbas-Cakmak, S., Fielden, S. D. P., Karaca U., Leigh, D. A., McTernan, C. T., Tetlow, D. J., Wilson, M. R. Science, 358:340–343.