An antiaromatic-walled nanospace.


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Type
Article
Change log
Authors
Yamashina, Masahiro 
Tanaka, Yuya 
Lavendomme, Roy 
Ronson, Tanya K 
Pittelkow, Michael 
Abstract

Over the past few decades, several molecular cages, hosts and nanoporous materials enclosing nanometre-sized cavities have been reported1-5, including coordination-driven nanocages6. Such nanocages have found widespread use in molecular recognition, separation, stabilization and the promotion of unusual chemical reactions, among other applications3-10. 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.

Description
Keywords
3402 Inorganic Chemistry, 3403 Macromolecular and Materials Chemistry, 3405 Organic Chemistry, 34 Chemical Sciences
Journal Title
Nature
Conference Name
Journal ISSN
0028-0836
1476-4687
Volume Title
574
Publisher
Springer Science and Business Media LLC
Rights
All rights reserved
Sponsorship
European Research Council (695009)
Engineering and Physical Sciences Research Council (EP/P027067/1)
the European Research Council (695009) the UK Engineering and Physical Sciences Research Council (EPSRC, EP/P027067/1)