Peripheral Templation Generates an M^II₆L₄ Guest‐Binding Capsule

Abstract

Pseudo-octahedral M II 6 L 4 capsules result from the subcomponent self-assembly of 2-formylphenanthroline, threefold-symmetric triamines, and octahedral metal ions. Whereas neutral tetrahedral guests and most of the anions investigated were observed to bind within the central cavity, tetraphenylborate anions bound on the outside, with one phenyl ring pointing into the cavity. This binding configuration is promoted by the complementary arrangement of the phenyl rings of the intercalated guest between the phenanthroline units of the host. The peripherally bound, rapidly exchanging tetraphenylborate anions were found to template an otherwise inaccessible capsular structure in a manner usually associated with slow-exchanging, centrally bound agents. Once formed, this cage was able to bind guests in its central cavity.

A supramolecular lanthanide separation approach based on multivalent cooperative enhancement of metal ion selectivity

“…It is worth pointing out that in this case all Cd II centers adopt nine-coordinating tricapped trigonal prismatic geometry. This is clearly different from the known Cd 4 L 6 -type cage assembled from another tris-tridentate ligand reported by Rizzuto et al 54 recently, where the Cd II adopted a six-coordinating octahedral geometry. So the crystal structure of our Cd 4 (L 1 ) 4 cage represents the first example of discrete supramolecular framework using nine-coordinated Cd II as vertices.…”

“…The formation of M 4 L 4 cages with various metal sources was inspiring, considering the facts that, until now, there was only one known discrete tetrahedral structure (Mg 4 L 4 ) made from AE II (alkaline earth metal ions), which was self-assembled from anionic 1,3-dicarbonyl ligands 56 ; and transition metal Cd II has been known to form only M 6 L 4 -type cages with tris-tridentate ligands 54 ; and furthermore, in general, both AE II and TM II (transition metal ions) favor smaller coordination numbers instead of nine-coordinating tricapped trigonal prismatic geometry in their supramolecular coordination compounds 57 – 59 .…”

Measuring ion-pairing and hydration in variable charge supramolecular cages with microwave microfluidics

“…However, the impact of dynamics in solution on reactivity is largely not characterized [2][3][4] . Poorly understood issues include the distribution of charge throughout these supramolecular systems, as well as the localization and rates of ion-pairing interactions [5][6][7][8][9] . These factors are often ignored in the design of supramolecular cages because they are not well understood, despite the fact that they have consequences for chemical applications 4,6,10 .…”

Self-Assembly in Polyoxometalate and Metal Coordination-Based Systems: Synthetic Approaches and Developments

“…Occasionally, the nanocages are able to accommodate more than one guest depending on their size of the host cage and the guest molecule. Nitschke et al reported the synthesis of a new class of supramolecular M II 6 L 4 pseudo-octahedra which can interact with guest molecules both internally and externally [107]. Moreover, the group demonstrated the importance of peripheral guests which template the formation of the Cu II 6 L 4 structure; they showed that the cage would be able to form based only on the self-assembly process or central template considerations.…”