Jump to main content
Jump to site search

Issue 19, 2019
Previous Article Next Article

Guest recognition enhanced by lateral interactions

Author affiliations

Abstract

A hexacationic triangular covalent organic cage, AzaEx2Cage6+, has been synthesized by means of a tetrabutylammonium iodide-catalyzed SN2 reaction. The prismatic cage is composed of two triangular 2,4,6-triphenyl-1,3,5-triazine (TPT) platforms bridged face-to-face by three 4,4′-bipyridinium (BIPY2+) spacers. The rigidity of these building blocks leads to a shape-persistent cage cavity with an inter-platform distance of approximately 11.0 Å. This distance allows the cage to accommodate two aromatic guests, each of which is able to undergo π–π interactions with one of the two TPT platform simultaneously, in an A–D–D–A manner. In the previously reported prism-shaped cage, the spacers (pillars) are often considered passive or non-interactive. In the current system, the three BIPY2+ spacers are observed to play an important role in guest recognition. Firstly, the BIPY2+ spacers are able to interact with the carbonyl group in a pyrene-1-carbaldehyde (PCA) guest, by introducing lateral dipole–cation or dipole–dipole interactions. As a consequence, the binding affinity of the cage towards the PCA guest is significantly larger than that of pyrene as the guest, even although the latter is often considered to be a better π-electron donor. Secondly, in the case of the guest 1,5-bis[2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethoxy]naphthalene (BH4EN), the pillars can provide higher binding forces compared to the TPT platform. Hence, peripheral complexation occurs when AzaEx2Cage6+ accommodates BH4EN in MeCN. Thirdly, when both PCA and BH4EN are added into a solution of AzaEx2Cage6+, inclusion and peripheral complexation occur simultaneously to PCA and BH4EN respectively, even though the accommodation of the former guest seems to attenuate the external binding of the latter. This discovery of the importance of lateral interactions highlights the relationship between the electrostatic properties of a highly charged host and its complexation behavior, and as such, provides insight into the design of more complex hosts that bind guests in multiple locations and modes.

Graphical abstract: Guest recognition enhanced by lateral interactions

Back to tab navigation

Supplementary files

Publication details

The article was received on 01 Feb 2019, accepted on 11 Apr 2019 and first published on 23 Apr 2019


Article type: Edge Article
DOI: 10.1039/C9SC00591A
Chem. Sci., 2019,10, 5114-5123
  • Open access: Creative Commons BY-NC license
    All publication charges for this article have been paid for by the Royal Society of Chemistry

  •   Request permissions

    Guest recognition enhanced by lateral interactions

    T. Jiao, K. Cai, Z. Liu, G. Wu, L. Shen, C. Cheng, Y. Feng, C. L. Stern, J. F. Stoddart and H. Li, Chem. Sci., 2019, 10, 5114
    DOI: 10.1039/C9SC00591A

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements