Supramolecular Self-Assembly and Investigation of an Anthracene-linked [Pd2L4]4+ Cage.

Abstract

Metallosupramolecular architectures are a relatively recent class of structures which have garnered focus for a wide variety of uses. One of these uses is to bind “guests” of interest within the structure. In order to achieve this binding, cages require cavities of the correct character and shape to bind the guest molecule. This report details the synthesis of a novel ditopic ligand, L1 with pyridyl donors and an anthracene core. This ligand was subsequently used to form a [Pd2L14]4+ cage which was characterised by 1H NMR spectroscopy and mass spectrometry. The host-guest properties of this cage were then investigated, demonstrating a lack of affinity for binding hydrophobic guests. Preliminary computational modelling provided a possible rationale for this lack of binding ability, suggesting that π-π interactions between anthracene linkers on the ligands resulted in a flattening of the cage structure and the lack of a well-defined cavity. This modelling was supported by 1H NMR spectroscopy which showed an upfield shift in the anthracene protons upon the formation of the cage which can be attributed to the aforementioned π-π interactions.