• 2.06 Chemistry

Accepting PhD Students

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Personal profile

Biography

Ph.D and Postdoctoral Opportunities

 

PhD Studentship Available (Deadline 15th January 2021)UEA competition funded position developing ruthenium-based phosphorescent probes for i-motif DNA

Post-Doctoral Position Coming Soon - 3 year Leverhulme-funded project on organoimido-tungstates, to be advertised January 2021 for April 2021 start.

Please do not hesitate to contact me to discuss either of these positions or to discuss self-fund PhD opportunities/post-doctoral fellowship applications

Biography

Dr. Fielden completed his MSci in Chemistry at the University of Bristol in 2000, before moving to the University of Glasgow where he graduated with a Ph.D in 2005 under the supervision of Prof. Leroy Cronin. He then spent two years working with Prof. Paul Kögerler at Ames Laboratory (Iowa State University) on the self-assembly and properties of polyoxometalates (POMs) and chiral magnetic materials. In 2007 he took up a postdoctoral position with Dr. Benjamin Coe at the University of Manchester, investigating redox-switchable NLO chromophores, and in 2010 was awarded a Marie Curie International Outgoing Fellowship. This took him back across the Atlantic to the laboratory of Prof. Craig Hill at Emory University, where he worked on POM functionalized photoelectrodes and the excited state properties of transition metal substituted POMs. He joined the UEA as a lecturer in 2012, transferring his Marie Curie reintegration year from Glasgow, and was promoted to Senior Lecturer in 2018.

John is interested in the synthesis and optical and photophysical properties of coordination compounds and clusters, particularly relating to solar energy conversion and non-linear optics. Since joining UEA the main focus of his work has been the study of arylimido-polyoxometalates (a-POMs) as non-linear optical chromophores, and as sensitisers and coadsorbents for the p-type dye-sensitised solar cell, both applications making use of the POM's properties as an electron acceptor. He is also working to develop luminescent sensors for i-motif DNA with Dr Zoë Waller (formerly UEA, now UCL School of Pharmacy). To see a YouTube video about this work, click here.

Click here to go to the Energy Materials Laboratory homepage.

Selected Publications

Sarah A. Alshehri, Ahmed Al-Yasari, Frank Marken and John Fielden
Covalently Linked Polyoxometalate-Polypyrrole Hybrids: Electropolymer Materials with Dual-Mode Enhanced Capacitive Energy Storage
Macromolecules 2020, ASAP.
DOI:
10.1021/acs.macromol.0c02354

Philip Spence, John Fielden and Zoë A. E. Waller
Beyond Solvent Exclusion: i-Motif Detecting Capability and An Alternative DNA Light-Switching Mechanism in a Ruthenium(II) Polypyridyl Complex
J. Am. Chem. Soc. 2020, 14213856-13866. 
DOI:
 10.1021/jacs0c04789. Click here to check out Zo
ë's YouTube video.

Simon N. Child, Radoslav Raychev, Nathan Moss, Benjamin Howchen, Peter N. Horton, Christopher C. Prior, Vasily S. Oganesyan and John Fielden.
Cobalt-based molecular electrocatalysis of nitrile reduction: evolving sustainability beyond hydrogen.
Dalton. Trans. 2019, 48, 9576-9580. Contribution to sustainability theme of d-block chemistry special issue and highlighted by ChemistryViews.
DOI:
 10.1039/c9dt00773c

Ahmed Al-Yasari, Philip Spence, Hani El Moll, Nick Van Steerteghem, Peter N. Horton, Bruce S. Brunschwig, Koen Clays and John Fielden.
Fine-tuning Polyoxometalate Non-Linear Optical Chromophores: A Molecular Electronic "Goldilocks" Effect.
Dalton. Trans. 2018, 4710415-10419. Inside front cover of New Talent Europe special issue.
DOI:
 10.1039/c8dt01491d

Ahmed Al-Yasari, Nick Van Steerteghem, Hayleigh Kearns, Hani El Moll, Karen Faulds, Joseph A. Wright, Bruce S. Brunschwig, Koen Clays and John Fielden.
Organoimido-Polyoxometalate Non-Linear Optical Chromophores: A Structural, Spectroscopic and Computational Study
Inorg. Chem. 2017, 56, 10181-10194.
DOI:
 10.1021/acs.inorgchem.7b00708

Hani El Moll, Fiona A. Black, Christopher J. Wood, Ahmed Al-Yasari, Anil Reddy Marri, Igor V. Sazanovich, Elizabeth A. Gibson and John Fielden. 
Increasing p-type dye sensitised solar cell photovoltages using polyoxometalates
Phys. Chem. Chem. Phys. 2017, 19, 18831-18835.
DOI:
 10.1039/C7CP01558E

 

John Fielden, Jordan M. Sumliner, Nannan Han, Yurii Gueletii, Xu Xiang, Djamaladdin G. Musaev, Tianquan Lian, and Craig L. Hill.
Water Splitting with Polyoxometalate-Treated Photoanodes: Enhancing Performance through Sensitizer Design
Chem. Sci. 20156, 5531-5543.
DOI:
10.1039/C5SC01439E

 

 

 

Career

  • 2012 – Lecturer in Energy Materials, UEA School of Chemistry (confirmed spring 2016)
  • 2010 – 2013 Marie Curie International Outgoing Fellow, Emory University (Atlanta, USA) and UEA
  • 2007 – 2010 Post-Doctoral Research Associate, University of Manchester
  • 2005 – 2006 Post-Doctoral Research Associate, Ames Laboratory (US Department of Energy)
  • 2001 – 2004 Ph.D in Inorganic Chemistry, University of Glasgow
  • 1996 – 2000 MSci in Chemistry, University of Bristol

Key Research Interests and Expertise

The Fielden group is currently working in the following areas:

  • Polyoxometalate-based non-linear optical chromophores and electropolymers. We have recently obtained a series of donor-acceptor chromophores based on polyoxometalates, including systems based on electropolymerizable pyrrole units.  The resulting materials obtain unusually high activity from moderate donor groups and short pi-systems, due to extension of charge transfer onto the POM. We are now working to develop ways of including these materials in films with bulk NLO activity and switchable responses.
  • New catalysts: We are using small, heteroleptic tripodal ligands as a platform to build catalysts for small molecule activation.  The ligands can coordinate a transition metal in a bidentate or tetradentate coordination pocket, while providing a pendant group for introduction of proton or electron relays.  These will allow controlled study of secondary coordination sphere effects. 
  • POM-derivatives as photosensitizers: We are investigating the use of POMs as electron acceptor units in push-pull chromophores.  These are designed to improve the efficiency of p-type dye-sensitized solar cells by retarding recombination of photo-excited electrons to NiO, one of the major sources of inefficiencies in these systems.  
  • New p-type semiconductor nanomaterials: In this project, supported by EU Marie Curie fellowship NanoCuI to Dr. Anil Reddy Marri, we are developing nanoporous copper iodide substrates as a replacement of the NiO p-type semiconductor in the p-type dye-sensitized solar cell (p-DSSC, collaboration with Dr. Andrew Mayes, UEA and Dr Elizabeth Gibson, Newcastle). p-DSSCs, in combination with conventional n-type DSSCs, could be used to make tandem DSSCs with better spectral coverage (light absorption at both electrodes) and photovoltage. However, at present p-DSSCs do not perform well enough to realise this promise, because the conductivity of the NiO substrate is poor. Gamma-CuI has an intrinsically much higher conductivity than NiO, so could produce much better devices, but the high surface area nanoporous electrodes needed for efficient dye sensitization do not yet exist. We are using chemical and electrochemical deposition methods to develop them.

External Activities

  • School Visits - The Deepings School, March 2017; Trent College, February 2016
  • Invited Research Talks: University of Glasgow (2017), FMOCS-PoCheMon (2016), University of Newcastle (2016), University of Southampton (2016); Emory University (2015), University of Central Lancashire (2015)
  • Outreach - Norwich Science Cafe 2013 - Talk on Artificial Photosynthesis
  • Outreach - Photon Science Institute/Manchester Museum of Science and Industry 2010 - Meet the Photon Scientist

Administrative Posts

Module Organiser: Year 2 Inorganic Chemistry (CHE-5301B)

Head of Second Year Chemistry

Chemistry Representative: Science Faculty Analytical Facilities User Group

 

Research Group Membership

Current Group Membership: Kevin Vincent (PDRA), Phil Spence, PhD student (joint BBSRC project with Zoë Waller, Pharmacy), Bethany Hood (PhD student), Sarah Alshehri (PhD student), Charles James (PhD student); plus undergraduate project students Jonas Konig-Hajji (MChem), Chloe Jordan (MChem) and Radoslav Raychev (BSc).

Fielden Group Autumn 2018

 

 

Fielden and Wright Groups, August 2017

 The Fielden and Wright Groups, August 2017

 From left to right: Farhana Haque (PhD, JAW), Trevor Simmons (PDRA, JAW), John Fielden, Joseph Wright, Anil Reddy Marri (Marie Sklodowska Curie Fellow, JF, 2015-17)

The Fielden Group, February 2015

From left to right: Simon Child, John Fielden, Natalia Sanchez Moreno, David Miko, Phil Spence, Hani El-Moll, Ahmed Al-Yasari

From left to right: Simon Child, John Fielden, Natalia Sanchez Moreno, David Miko, Phil Spence, Hani El-Moll, Ahmed Al-Yasari

And among the Ziggurats...

Fielden group outside the UEA Ziggurat buildings

Fielden group outside the UEA Ziggurat buildings

 

 

Network

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