Functional Networks of Molecular Capsules

Lead Research Organisation: University of Cambridge
Department Name: Chemistry

Abstract

Drawing on experience in the Nitschke group in the areas of self-assembled metal-organic cage materials, light-induced transformations of supramolecular assemblies, and systems chemistry, the proposed research will investigate potential applications of metal-organic cages for catalysis. The combined abilities of metal-organic cages to create pre-organised environments, spatially confine reactive species, and to reversibly assemble/disassemble upon a change in conditions resemble those exploited by enzymes to manipulate reaction kinetics and provide opportunities for new modes of catalysis.

The proposed research is currently divided into two sub-projects: 1. 'Light-controlled reversible phase transfer of metal-organic capsules', and 2. 'Photocatalytic water activation within a self-assembled M4L6 cage'.

In the first, a polar and a non-polar cage, within separate phases and differing by one ligand subcomponent, converge to the polar cage in the absence of light, while the presence of light drives a pathway of equilibration between the two, whose equilibrium distribution favours the non-polar cage.

In the second sub-project, an open, water-soluble tetrahedral cage is proposed whose inward-facing pyridone O-donor atoms may accommodate 4 Mn(III) ions in proximity to one another. The vertices of the cage serve as photoredox catalysts, successively oxidising the Mn cluster in the presence of light and a terminal oxidant. Water, capable of passing through the cage and/or binding to free Mn coordination sites may then be oxidised to dioxygen and protons, while returning the Mn cluster to its initial state.

Publications

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Grommet AB (2018) Anion Exchange Drives Reversible Phase Transfer of Coordination Cages and Their Cargoes. in Journal of the American Chemical Society

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509620/1 01/10/2016 30/09/2021
1800654 Studentship EP/N509620/1 01/10/2016 30/09/2020 Jack Benjamin Hoffman
 
Description The research funded on this grant has led to a novel methodology for chemical separation, in which self-assembled molecular cages encapsulate a desired 'cargo' in one liquid phase within a biphasic system. The addition of a chemical stimulus then induces the transfer of cage and cargo to a secondary phase. This process is reversible upon the addition of a secondary chemical stimulus and the driving forces underlying this behaviour are understood quantitatively. This methodology was developed in tandem with a new theoretical framework to explain this phase-transfer behaviour in a more general sense. This project therefore generated new knowledge regarding phase-transfer, which may have implications for chemical transfer between cells, for example.

My research has also led to a general theoretical framework for the design of oscillatory chemical networks. The field of supramolecular chemistry has largely been concerned with chemical systems at equilibrium. However, the chemical complexity observed in cells is attributable to interconnected chemical reactions occurring out of equilibrium. Chemical oscillation is an inherently out-of-equilibrium phenomenon and is fundamental to many aspects of cellular function. This work is therefore an important stepping stone towards the design of functional out of equilibrium chemical networks.
Exploitation Route My research output relating to phase-transfer may be taken forward by biological chemists to further investigate the role of intracellular and extracellular ion concentrations on chemical uptake and release by cells, under thermodynamic control. The phase-transfer methodology may also be further developed for the purification of compounds of commercial significance. These findings may therefore have relevance to academia, the pharmaceutical industry, and chemical industry in general.
Sectors Chemicals,Pharmaceuticals and Medical Biotechnology

 
Description A general framework for the design of chemical oscillators 
Organisation University of Cambridge
Country United Kingdom 
Sector Academic/University 
PI Contribution A collaboration with Prof. David Wales (dept. of chemistry, The University of Cambridge) involved the creation of a novel methodology and software for the design of oscillatory reaction networks. My contributions were the project conception, developing the methodology, and writing the associated software.
Collaborator Contribution Prof. Wales advised on the mathematical and software aspects of this project.
Impact The output of this work has been submitted for publication.
Start Year 2018