Issue 19, 2020

Preparation of cage-shaped hexakis(spiroborate)s


In previous research studies, various types of prismatic cage-shaped molecular containers have been prepared and evaluated in terms of their guest inclusion properties. Basically, most of these molecular cages have a cationic or electron-deficient nature, and exhibit strong affinity mainly toward electron-rich aromatic guests. On the other hand, there is no report concerning anionic prismatic cages that are expected to recognize cationic polyaromatic guests with various structures and functions. In this manuscript, we present the preparation of hexakis(spiroborate)-type molecular cages, which was achieved by the reaction of phenylene- or biphenylenebis(dihydroxynaphthalene), hexahydroxytriphenylene, and boric acid in N,N-dimethylformamide. Their triangular prismatic hollow structures were confirmed by X-ray crystallographic analysis, and it was found that both phenylene- and biphenylene-bridged spiroborate cages have internal cavities of the corresponding size. It was also revealed that tetra(n-butylammonium) cations located inside the cavity and between the two adjacent spiroborate cages resulted in the formation of a one-dimensional columnar array. The molecular recognition behavior of the spiroborate cages was evaluated using tris(pyridinium)triazines as tricationic aromatic guests. 1H NMR measurement implied that a discrete 1 : 1 host–guest complex was formed when 1 equiv. of guest was added to the cage, whereas infinite one-dimensional aromatic stacks were constructed by the addition of 2 equiv. of guest.

Graphical abstract: Preparation of cage-shaped hexakis(spiroborate)s

Supplementary files

Article information

Article type
11 Mar 2020
23 Apr 2020
First published
04 May 2020

Org. Biomol. Chem., 2020,18, 3717-3723

Preparation of cage-shaped hexakis(spiroborate)s

H. Danjo, Y. Masuda, Y. Kidena, M. Kawahata, K. Ohara and K. Yamaguchi, Org. Biomol. Chem., 2020, 18, 3717 DOI: 10.1039/D0OB00518E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity