Self-assembled conjoined-cages.

Samantray, Sagarika; Krishnaswamy, Shobhana; Chand, Dillip K · Nat Commun · 2020

basic_science · Level V

Where this comes from

Abstract

A self-assembled coordination cage usually possesses one well-defined three-dimensional (3D) cavity whereas infinite number of 3D-cavities are crafted in a designer metal-organic framework. Construction of a discrete coordination cage possessing multiple number of 3D-cavities is a challenging task. Here we report the peripheral decoration of a trinuclear [Pd<sub>3</sub>L<sub>6</sub>] core with one, two and three units of a [Pd<sub>2</sub>L<sub>4</sub>] entity for the preparation of multi-3D-cavity conjoined-cages of [Pd<sub>4</sub>(L<sup>a</sup>)<sub>2</sub>(L<sup>b</sup>)<sub>4</sub>], [Pd<sub>5</sub>(L<sup>b</sup>)<sub>4</sub>(L<sup>c</sup>)<sub>2</sub>] and [Pd<sub>6</sub>(L<sup>c</sup>)<sub>6</sub>] formulations, respectively. Formation of the tetranuclear and pentanuclear complexes is attributed to the favorable integrative self-sorting of the participating components. Cage-fusion reactions and ligand-displacement-induced cage-to-cage transformation reactions are carried out using appropriately chosen ligand components and cages prepared in this work. The smaller [Pd<sub>2</sub>L<sub>4</sub>] cavity selectively binds one unit of NO<sub>3</sub><sup>-</sup>, F<sup>-</sup>, Cl<sup>-</sup> or Br<sup>-</sup> while the larger [Pd<sub>3</sub>L<sub>6</sub>] cavity accommodates up to four DMSO molecules. Designing aspects of our conjoined-cages possess enough potential to inspire construction of exotic molecular architectures.