Designing “surface sprinters”: molecular machines that rapidly “walk” on the surfaces

Background

Molecular machines have fascinated scientists for many decades. Significant progress in this area was recognised by a Nobel prize in 2016. An important class of molecular machines is surface molecular walkers, molecules that can travel along a surface. However, the movement in such systems has so far been relatively slow which hampers their applications to bulk materials and devices.

Objectives

The aim of this project is to design molecules that can move very rapidly on surfaces, covering macroscopic distances (e.g., millimetres) in reasonable time (e.g., hours). These molecular machines (we dubbed them “molecular sprinters”) rely on very fast chemical reactions of the sprinters with the surface sites.

The first objective is hence to develop such chemical reactions. In order to keep the sprinter attached to the surface at all times, the reactions need to form a bond to the new site before the bond to the old site is broken.

The second objective is to attach the sprinter molecules to the appropriate surfaces and visualize their movement.

The third objective of the project is to make the movement of molecular sprinters directional (rather than random). This requires external driving force. We propose to use two approaches. In the first approach, the sprinters will possess electric charge so that they can be directed by the application of external electric field, similar to how ions are moved in electrophoresis experiments. In the second approach, we will use fast and directional flow of solvent to “drag” the sprinters along on the surface.

Experimental approach

We have already selected several fast chemical reactions to be tested for molecular sprinting, based on the analysis of literature data. The reactions will first be probed in bulk solutions, and the successful candidates will then be applied to the sprinters. We will use self-assembled monolayers of functional organic molecules on the surface of gold or silicon dioxide (e.g., glass) as supports for molecular sprinters.

The movement of functionalised molecular sprinters will be monitored using a variety of well-established techniques. The main methods will be atomic force microscopy and fluorescence microscopy available in York.

Novelty

Making molecular machines that cover macroscopic distances is unchartered territory. However even if we fail to make the very fast molecular sprinters, the sprinting reactions which we develop will be very beneficial for other dynamic supramolecular systems, including adaptive polymers and networks, self-evolving and self-replicating systems.

Development of directed (rather than random) sprinter movement is the most exciting but also the riskiest part of the project. Scientists have long been fascinated by the prospect of non-random movement of molecules using external stimuli. Despite some progress, the application of bulk stimuli like electric field or solvent flow for directing chemical reactions is to the best of our knowledge unprecedented.

Training

You will be working alongside a postdoc who will start a few months earlier to prepare the ground for the project. The postdoc will be more experienced in synthetic chemistry so your contribution will be focussed on supramolecular, physical organic and surface chemistry. The project is very interdisciplinary and will hence provide training in many areas, including synthetic and mechanistic chemistry and a variety of analytical techniques, from conventional NMR and MS to more advanced fluorescence and atomic force microscopies.

You will follow our core cohort-based training programme to support the development of scientific, transferable and employability skills, as well as training on specific techniques and equipment. Training includes employability and professionalism, graduate teaching assistant training and guidance on writing papers. https://www.york.ac.uk/chemistry/postgraduate/training/idtc/idtctraining/  

There will be opportunities for networking and sharing your work both within and beyond the University. Funding is provided to enable you to attend conferences and external training. The department also runs a varied and comprehensive seminar programme.

Equality and Diversity

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/

As part of our commitment to Equality and Diversity, and Widening Participation, we are working with the YCEDE project (https://ycede.ac.uk/) to improve the number of under-represented groups participating in doctoral study.  

Entry requirements 

You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a relevant related subject.  

For more information about the project, click on the supervisor’s name above to email them. 

For more information about the application process or funding, please click on email institution.

Guidance for applicants: https://www.york.ac.uk/chemistry/postgraduate/apply/

Submit an online PhD in Chemistry application: https://www.york.ac.uk/study/postgraduate/courses/apply?course=DRPCHESCHE3

The start date of the PhD will be 16 September 2024

Application may close early if a suitable candidate is identified.