Nanotubes and fullerenes are amongst the most promising new materials, and insights in the nature of bonding and the levels of aromaticity in their lowest singlet and triplet electronic states can be used to guide the search for molecular systems of this type with tuneable properties. We have recently developed a computational protocol for constructing surfaces of equally magnetically shielded points, ‘shielding isosurfaces’, in the space surrounding a molecule [1-3]. These shielding isosurfaces demonstrate very clearly the differences between single, double and triple chemical bonds, as well as those between aromatic and antiaromatic molecules.
The aim of this project is to apply this computational protocol to nanotubes and fullerenes. It is expected that this research will provide enhanced understanding of the chemical bonding and structure of these systems and of the ways in which their properties can be modified: In endohedral fullerenes, through additional atoms, ions, or clusters that can be enclosed within their inner spheres, and in nanotubes, by doping. By examining both the lowest singlet and triplet electronic states of nanotubes and fullerenes we aim to address the possibility of excited state aromaticity changes, which are essential in the search for new materials with tuneable properties.
The singlet and triplet geometries of selected nanotubes and fullerenes will be optimized using a range of density functional theory (DFT) methods, in combination with suitable modern basis sets. We intend to make use of at least three different exchange-correlation functionals, the popular B3LYP and the newer M06 and M06-2X from Truhlar’s group, with dispersion corrections, in order to deal more accurately with weak interactions. Magnetic shielding tensor calculations will be carried out using the same DFT exchange-correlation functionals, utilising the symmetry of nanotubes and fullerenes as much as possible, in order to reduce computational effort. This will require writing programs for generating the positions of the symmetry-unique points for each molecule, at which the magnetic shielding tensors will be evaluated and then replicated by symmetry. All calculations will be carried out with a well-known commercial quantum chemistry package, GAUSSIAN. The shielding isosurfaces will be generated and visualized using the popular visual molecular dynamics code VMD.
Magnetic shielding isosurfaces and contour plots are arguably the most versatile computational tool for studying, at the same time, chemical bonding and aromaticity of molecules in different electronic states. This will be the first application of this tool to very large systems which are recognized as promising new materials.
The work on this project will provide the student with a sound basis in using quantum and computational chemistry in the design of new materials, with hands-on knowledge of popular computational codes and experience in computer programming. Full training will be provided in data analysis, data storage, and data presentation. Computational chemistry and programming are valuable transferrable skills. The student will participate in group meetings and in national and international conferences, allowing development of oral and presentation skills.
All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/idtc/
The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/
You should expect hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject. Please check the entry requirements for your country: https://www.york.ac.uk/study/international/your-country/
This project is available to students from any country who can fund their own studies. The Department of Chemistry at the University of York is pleased to offer Wild Fund Scholarships. Applications are welcomed from those who meet the PhD entry criteria from any country outside the UK. Scholarships will be awarded on supervisor support, academic merit, country of origin, expressed financial need and departmental strategy. For further details and deadlines, please see our website: View Website
 P. B. Karadakov, P. Hearnshaw and K.E. Horner, J. Org. Chem. 81 (2016) 11346.
 P. B. Karadakov and K. E. Horner, J. Chem. Theory Comput. 12 (2016) 558.
 P. B. Karadakov, M. A. H. Al-Yassiri and D. L. Cooper, Chem. Eur. J. 24 (2018) 16791.