Dr John Dennis
Reader in Molecular Nanostructural Materials
G O Jones 119, Mile End
Dr Dennis's research centres on the synthesis, purification, and spectroscopic characterization of novel fullerene related materials. Dr Dennis conducted pioneering work in the synthesis and purification of fullerenes. During August 1990 Dr Dennis beacme the first researcher to synthesize and purify the archetypal fullerene C60 (i.e., to do both) and since then was the first to purified more fullerenes isomers than all other researchers combined; including all 9 known isomers of the third most abundant fullerene C84. To this end he has developed several counter to proper practice HPLC techniques for fullerene purification that are now commonly used in many fullerene research labs throughout the world. His present research interest include:
- Temperature-dependent structural studies: through NMR spectroscopy (molecular and dynamical) and XRD (crystal). Temperature-dependant vibrational studies via FTIR and FT-Raman.
- Double-walled nanotubes: developing the production and purification of double-walled carbon nanotubes (by both pulsed arc, and CVD techniques), and to exploit the durability of double-walled nanotubes to produce more reliable nano-transistors, and materials with potential applications for field emission-based flat screen displays.
- Carbon peapods: By encapsulating metal element containing endohedral fullerenes within carbon nanotubes tube, the band gap tubes can be narrowed (at the points corresponding to the positions of the endohedral fullerene). Preliminary results indicate these carbon peapods can be p-type, n-type, or am-bipolar, depending on the encapsulated atom. The effects of the encapsulated atom on the electronic transport of the fullerene is investigated.
- Endohedral fullerenes as contrast agents for MRI: Gadolinium-containing endohedral fullerenes are promising species for contrast enhancement in MRI, these species have several advantages over conventional agents. The incarcerated highly toxic Gd3+ ion is severely sterically hindered to dissociation, and they are about 20 times as effective, thus are required in much smaller doses. We, in collaboration with researchers at the Institute of Chemistry at the Chinese Academy of Sciences in Beijing are currently investigating functionalisation of these species to make them water-soluble and specific tissue targeting. For example, we have recently produced bone-targeting Gd-based endohedral fullerenes.
- Quantum information processing: The ESR of the nitrogen-containing endohedral fullerene iNC60 has hyperfine lines at least two orders of magnitude narrower then any other known radical, making it a possible qubit candidate for quantum computation. Having recently performed the first (and still only) isolation of iNC60, I intend to systematically investigate the potential of nitrogen- and phosphorous-containing incar-fullerenes, as dimers as novel building-block materials for electron spin-based scalable solid-state quantum computation.
- Isomer-pure fullerene and endohedral fullerene-based Transistors: Recently our group has begun researching the use of fullerenes and endohedral fullerenes in semi-conductor devices, including transistors.
Before joining QMUL, Dr Dennis conducted postdoctoral research under a series of personal research fellowships from the Australian Research Council, the Japan Society for the Promotion of Science, and the Alexander von Humboldt Foundation. He gained his D.Phil. under the supervision of Prof Harry Kroto at the University of Sussex in 1993.
- Liu T, Abrahams I and Dennis T (2020). Conformational Analysis of PCBM via 2nd-Order Proton NMR Spin-Spin Coupling Effects. American Chemical Society Journal of Physical Chemistry Letters 10.1021/acs.jpclett.0c01421
- LIU T, ABRAHAMS I and DENNIS T (2018). Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by 13C NMR and UV-Vis Absorption Spectroscopy and High Performance Liquid Chromatography. American Chemical Society Journal of Physical Chemistry A vol. 122, (16) 4138-4152. 10.1021/acs.jpca.8b00713
- Peci T, Dennis TJS and Baxendale M (2015). Iron-filled multiwalled carbon nanotubes surface-functionalized with paramagnetic Gd (III): A candidate dual-functioning MRI contrast agent and magnetic hyperthermia structure. Carbon vol. 87, (C) 226-232. 10.1016/j.carbon.2015.01.052