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An antiaromatic-walled nanospace

DOI: 10.1038/s41586-019-1661-x DOI Help

Authors: Masahiro Yamashina (University of Cambridge; Tokyo Institute of Technology) , Yuya Tanaka (Tokyo Institute of Technology) , Roy Lavendomme (University of Cambridge) , Tanya K. Ronson (University of Cambridge) , Michael Pittelkow (University of Copenhagen) , Jonathan R. Nitschke (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 574 , PAGES 511 - 515

State: Published (Approved)
Published: October 2019
Diamond Proposal Number(s): 15768

Abstract: Over the past few decades, several molecular cages, hosts and nanoporous materials enclosing nanometre-sized cavities have been reported1,2,3,4,5, including coordination-driven nanocages6. Such nanocages have found widespread use in molecular recognition, separation, stabilization and the promotion of unusual chemical reactions, among other applications3,4,5,6,7,8,9,10. Most of the reported nanospaces within molecular hosts are confined by aromatic walls, the properties of which help to determine the host–guest behaviour. However, cages with nanospaces surrounded by antiaromatic walls have not yet been developed, owing to the instability of antiaromatic compounds; as such, the effect of antiaromatic walls on the properties of nanospaces remains unknown. Here we demonstrate the construction of an antiaromatic-walled nanospace within a self-assembled cage composed of four metal ions with six identical antiaromatic walls. Calculations indicate that the magnetic effects of the antiaromatic moieties surrounding this nanospace reinforce each other. This prediction is confirmed by 1H nuclear magnetic resonance (NMR) signals of bound guest molecules, which are observed at chemical shift values of up to 24 parts per million (ppm), owing to the combined antiaromatic deshielding effect of the surrounding rings. This value, shifted 15 ppm from that of the free guest, is the largest 1H NMR chemical shift displacement resulting from an antiaromatic environment observed so far. This cage may thus be considered as a type of NMR shift reagent, moving guest signals well beyond the usual NMR frequency range and opening the way to further probing the effects of an antiaromatic environment on a nanospace.

Subject Areas: Chemistry


Instruments: I19-Small Molecule Single Crystal Diffraction