Vernier template synthesis of complex molecular knots
Inorganic Molecular Chemistry - Synthesis and Characterisation
Final Report Abstract
The aim of this project, which was the utilisation of a Vernier-templating strategy for the preparation of complex molecular knots, could successfully be realised. By the targeted design of a coordinative mismatch between a pyridinedicarboxylamide (pdc) based ligand and lanthanoid ions we could prepare composite knots of unprecedented complexity with a 378-atom-long closed-loop and a ligand strand length of about 40 nm. Reaction of the ligands with lanthanoid ions first yields the open knot complexes, which can subsequently be closed via ring closing metathesis. The purely organic knots can be obtained by removal of the lanthanoid ions with the aid of ethyl ammonium fluoride. The handedness of the individual components of these hierarchically knotted molecular architectures can be controlled by the sequence of stereogenic centres in the ligand and by adapting the number of pdc units in the ligand strand a further knot topology could be realised (the granny knot). In this sense the established strategy does not only expand the range of topologies but also improves the accessibility of previously described examples. Characterisation of expanded knotted molecules is a challenge, with normal 1 H NMR spectra typically being composed of broad sets of signals. In this project the interpretation of paramagentic shifts of 1 H NMR spectra of YbIII derivatives of the open knots was a key method for the establishment of the expected structure and geometry of the compounds under study. The results of this study were published in "Science" and were highlighted in Chemical & Engineering News.
Publications
- Autonomous fuelled directional rotation about a covalent single bond. Nature 2022, 604, 80-85
S. Borsley, E. Kreidt, D. A. Leigh, B. M. W. Roberts
(See online at https://doi.org/10.1038/s41586-022-04450-5) - Insights from an information thermodynamics analysis of a synthetic molecular motor. Nat. Chem. 2022, 14, 530-537
S. Amano, M. Esposito, E. Kreidt, D. A. Leigh, E. Penocchio, B. M. W. Roberts
(See online at https://doi.org/10.1038/s41557-022-00899-z) - Vernier template synthesis of molecular knots. Science 2022, 375, 1035-1041
Z. Ashbridge, E. Kreidt, L. Pirvu, F. Schaufelberger, J. Halldin Stenlid, F. Abild-Pedersen, D. A. Leigh
(See online at https://doi.org/10.1126/science.abm9247)
