Dr Victor Chechik

01904 324185
E-mail: victor.chechik@york.ac.uk

Mechanistic chemistry of free radicals, EPR spectroscopy and functional nanoparticles

The research in the Chechik group involves detecting and studying free radical intermediates, using stable radicals as probes for supramolecular assemblies and nanostructures, and developing functional nanomaterials (e.g., for medicinal applications). We often use EPR spectroscopy in free radical research (we have three CW-EPR spectrometers operating at X- and Q-bands). Developing mechanistic understanding is often the driving force for our research, and we collaborate widely on mechanistic problems. Current projects include the following areas:

Short-lived radical intermediates

Short-lived free radical intermediates play a key role in many important processes, including combustion, polymerisation, atmospheric reactions, catalysis and biological process. However, they are difficult to study as they are usually present at extremely low concentrations. We are interested in unravelling the mechanisms of radical reactions using spin trapping approach and EPR spectroscopy, and we are involved in development of other methods for radical trapping. We study free radicals in collaborations with atmospheric chemists at WACL, plasma physicists at YPI, materials chemists, and industry.

photo of plasma  plasma scheme  EPR‌‌‌

Plasma jet and EPR spectrum of trapped H·/D· radicals formed in plasma 

EPR studies of nanostructured materials

Although most free radicals are extremely reactive, some are very stable. Well known examples of stable radicals include molecular oxygen and nitrogen oxides (NO, NO2). Organic stable free radicals are excellent probes for studying complex systems (such as gels, nanoparticles, colloidal solutions, lipid bilayers, host-guest complexes etc) with EPR spectroscopy, as only the signals of the radical probes are observed. The EPR spectra provide wealth of information about molecular structure and organisation, local polarity, reactivity in these systems.

gel EPR

Vanadyl-labelled alginate gel and EPR spectra of a nitroxide-labelled gel 

Magnetic nanoparticles for therapeutic delivery

Magnetic nanoparticles (e.g., with an iron or iron oxide core) bring together many properties of supramolecular systems. They can be easily functionalised with organic ligands that determine their solubility and other properties, several functional ligands can be attached to the same nanoparticle, they can be guided by static magnetic field and heated by oscillating magnetic field. We are interested in using these materials for medicinal applications. In particular, we work on developing functional organic coatings for nanoparticles that would provide active targeting and delivery of therapeutic agents.

‌‌magn NPs  TEM

Magnetic nanoparticles

Other current projects in the Chechik group include application of EPR spectroscopy for studying charge carriers in semiconductor nanoparticles, and electroorganic radical chemistry.

We are affiliated with the Durham-York research consortium chem-mechanism.uk

Selected Recent Publications

  •  J. A.  Grant, Z. Lu, D. S. Yufit, D. E. Tucker, V. Chechik, AnnMarie C. O’Donoghue, Nitron:  From  Bench-Stable  Carbene  to  New  Blatter-Type  Radicals, Nat. Comm. 2017, 815088.
  • Y. Gorbanev, D. Leifert, A. Studer, D. O’Connell, V. Chechik, Initiating radical reactions with non-thermal plasma, Chem. Comm. 2017, 53(26), 3685-3688.
  • R. Smith, B. Garrett, K. Naqvi, A. Fülöp, S. Godfrey, J. Marsh, V. Chechik, Mechanistic Insights into the Bleaching of Melanin by Alkaline Hydrogen Peroxide, Free. Radic. Biol. Med. 2017, 108, 110-117.
  • C. A. Unsworth, B. Coulson, V. Chechik, R. E. Douthwaite, Aerobic oxidation of benzyl alcohols to benzaldehydes using monoclinic bismuth vanadate nanoparticles under visible light irradiation: Photocatalysis selectivity and inhibition, J. Catal. 2017354, 152-159.
  • V. Lloveras, E. Badetti, K. Wurst, V. Chechik, J. Vidal-Gancedo, Magnetic and Electrochemical Properties of a Diradical TEMPO-substituted Disulfide in Solution, Crystal and on Surface, Chem. Eur. J. 2016, 22(5), 1805-1815.
  • Y. Gorbanev, D. O’Connell, V. Chechik, Non-thermal plasma in contact with water: The origin of species, Chem. Eur. J. 2016, 22(10), 3496-3505.
  • E. Draper, R. Schweins, R. Akhtar, D. Adams, P. Groves, M. Zwijnenburg, V. Chechik, Reversible photoreduction as a new trigger for photoresponsive gels, Chem. Mater. 2016, 28(17), 6336-6341.
  • E. J. Johnston, E. L. Rylott, E. Beynon, A. Lorenz, V. Chechik, N. C. Bruce, Monodehydroascorbate reductase mediates TNT toxicity in plants, Science 2015, 349 (6252), 1072-1075.
  • E. G. Ionita, A. M. Ariciu, D. K. Smith, V. Chechik, Ion exchange in alginate gels – dynamic behaviour revealed by electron paramagnetic resonance, Soft Matter 2015, 11 (46), 8968-8974.