Multicomponent Metallo-Supramolecular Nanocapsules Assembled from Calix[4]resorcinarene-Based Terpyridine Ligands

Abstract

Tetrafunctionalized calix[4]resorcinarene cavitands commonly serve as supramolecular scaffolds for construction of coordination-driven self-assembled capsules. However, due to the calix-like shape, the structural diversity of assemblies is mostly restricted to dimeric and hexameric capsules. Previously, we reported a spontaneous heteroleptic complexation strategy based on a pair of self-recognizable terpyridine-based ligands and Cd II ions. Building on this complementary ligand pairing system, herein three types of nanocapsules, including a dimeric capsule, a Sierpinśki triangular prism, and a cubic star, could be readily obtained through dynamic complexation reactions between a tetratopic cavitand-based ligand and various multitopic counterparts in the presence of Cd II ions. The dimeric capsular assemblies display the spacer-length-dependent self-sorting behavior in a four-component system. Moreover, the precise multicomponent selfassembly of a Sierpinśki triangular prism and a cubic star possessing three and six cavitand-based motifs, respectively, demonstrates that such self-assembly methodology is able to efficiently enhance architectural complexity for calix[4]resorcinarene-containing metallo-supramolecules.

Reaction Monitoring and Structural Characterisation of Coordination Driven Self-Assembled Systems by Ion Mobility-Mass Spectrometry

“…The coordination of hexafluorophosphate counterions is the driving force for the folding and unfolding of the supramolecule. This is a similar example to the previously discussed charge and counterion induced topological changes, but on a "tertiary" structural level (Mallis et al, 2019;He et al, 2020). Furthermore, two separate instrumental methodologies for switching between the two structures were explored, demonstrating the suitability of IMS-MS for probing the properties of complex structures such as oligorotaxanes.…”

“…An exciting example of structural assignment using Ω was reported in the synthesis of multiple supramolecular cages based on Calixresorcinarene ligands ( He et al, 2020 ). Three cages were formed with ligands that varied only in the length of the π-spacer groups.…”

“… Observation of two distinct cubic star structures seen in ion mobility dependent on assembly charge. These two structures are represented by the two different families of peaks (pink lines) observed with a smaller transitionary family observed in between ( He et al, 2020 ). …”

“…Other recent investigations into self-sorting have utilised IMS-MS to varying degrees. Some, such as investigations of ligand spacer length effects on product heteroleptic macrocycles and cages, use IMS-MS to show the clear separation by both IMS and MS of the sorted assemblies ( Wang et al, 2018c ; He et al, 2020 ). In these studies IMS-MS is effective because the spacer length change creates clear structural and m/z differences that can be identified.…”

An Adaptive Resorcinarene Hemicarcerand

“…The cyclic condensation products of resorcinol with aldehydes are prevalently used in chromatography, [12] and molecular recognition [13] and are under investigation for utilization as ligands for transition metals [14] e. g. in catalysis [15] . Furthermore, resorcinarenes are employed for assembling host‐guest complexes, which isolate the incarcerated guest from the outer environment [16] and are recently examined as nanocontainers [17] e. g. for supramolecular catalysis [18] . These capsules are assembled through covalent linkages of two hemispherical resorcinarene units and a distinction is drawn between carcerands and hemicarcerands.…”