Guest-Induced Reversible Transformation between an Azulene-Based Pd2L4 Lantern-Shaped Cage and a Pd4L8 Tetrahedron

Journal of the American Chemical Society, vol. 145, pp. 25365–25371

Abstract

Azulene, a blue structural isomer of naphthalene, is introduced as the backbone for a new family of Pd(II)-based self-assemblies. Three organic ligands, equipped with varying donor groups, produce three [Pd 2 L 4 ] cages of different cavity dimensions. Unexpectedly, the addition of organic disulfonate guests to the smallest lantern-shaped cage (featuring pyridine donors) led to a rapid and quantitative transformation to a distorted-tetrahedral [Pd 4 L 8 ] species. On the contrary, [Pd 2 L 4 ] cages formed from ligands with isoquinoline donors either just encapsulated the guests or showed no interaction. The tetrahedral species could be fully reverted back to its original [Pd 2 L 4 ] topology by capturing the guest by another, stronger binding [Pd 2 L′ 4 ] coordination cage, narcissistically self-sorting from the first cage. The azulenes, serving as colored hydrocarbon backbones of minimal atom count, allow one to follow cage assembly and guest-induced transformation by the naked eye. Furthermore, we propose that their peculiar electronic structure influences the system’s assembly behavior.

Authors 4

1. Alexandre Walther

   TU Dortmund University

   Affiliation as printed

   Department of Chemistry and Chemical Biology, TU Dortmund University, Otto Hahn Straße 6, 44227 Dortmund, Germany

2. Irene Regeni Aachen

   Leiden University · TU Dortmund University

   Affiliation as printed

   Department of Chemistry and Chemical Biology, TU Dortmund University, Otto Hahn Straße 6, 44227 Dortmund, Germany

   Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands

3. Julian J. Holstein

   TU Dortmund University

   Affiliation as printed

   Department of Chemistry and Chemical Biology, TU Dortmund University, Otto Hahn Straße 6, 44227 Dortmund, Germany

4. Guido H. Clever corresponding

   TU Dortmund University

   Affiliation as printed

   Department of Chemistry and Chemical Biology, TU Dortmund University, Otto Hahn Straße 6, 44227 Dortmund, Germany