Multicavity [Pd_nL₄]²ⁿ⁺ Cages with Controlled Segregated Binding of Different Guests

Abstract

Multicavity [Pd(L)] metallosupramolecular cages based on long backboned ligands are an attractive approach to increasing molecular size without loss of the binding specificity conferred by small cavity [Pd(L)] assemblies. We herein report the synthesis of two double cavity polypyridyl [Pd(L)] cages that bind cisplatin [Pt(NH)Cl] within their internal cavities and interact with triflate (TfO) on their exohedral faces. We also report the first example of a triple cavity [Pd(L)] cage. This cage differs in that the central cavity is phenyl-linked rather than having the pyridyl core as in the peripheral cavities. The difference in cavity character results in selective guest binding of cisplatin in the peripheral cavities, with triflate binding within the central cavity and on the exohedral faces of the peripheral palladium(II) ions. All the cavities could be simultaneously filled by introducing both cisplatin and triflate concurrently, providing the first example of a discrete metallosupramolecular architecture with segregated guest binding in different designed internal cavities. The ligands and cages were characterized by NMR spectroscopy, mass spectrometry, elemental analysis, and, in one case, X-ray crystallography.

Supramolecular Maleate Adducts of Copper(II) 12‐Metallacrown‐4: Magnetism, EPR, and Alcohol Sorption Properties

“…Polynuclear complexes and supramolecular assemblies with porous lattices based on polynuclear blocks are attracting attention as the potential basis for multifunctional materials due to their ability to absorb different substrates, as well as other physical properties Inasmuch as the properties of the starting compound – the “building block” – usually pre‐determine the properties of the resultant coordination polymer or supramolecular assembly based on it, the choice of building block is important. The combination of physical and chemical properties of the chosen block with the ability of a porous lattice in the resulting compound to interact with certain substrates enables use of these assemblies as active constituents of sensors,, as magnetic, or luminescent, materials with tunable properties, as sorbents,, or in separation processes …”

Polyaromatic molecular peanuts

“…The unusual heteroleptic encapsulation most probably arises from the cooperative changes in volume of the linked cavities upon guest encapsulation, which is mechanistically different from a previous heteroleptic binding in three open cavities with different binding sites18. Optimized host–guest structures of 2b′ (R=−H) using force-field calculations showed that the volume of the second cavity increases by 6% to 530 Å 3 upon encapsulation of aliphatic guest 4a (210 Å 3 ) in the first cavity (see Supplementary Fig.…”

“…1a)13. There have been several synthetic reports on multicomponent nanostructures with two or three open cavities capable of binding relatively small ions and metal complexes, such as Cl − , PF 6 − and cisplatin1415161718. However, imitation of the characteristic core–shell structures has yet to be accomplished on the nanoscale.…”

Synthesis and Applications of Endohedrally Functionalized Metal‐Ligand Cage Complexes

“…This concept can be extended to the formation of multicavity cages of Pd n L 4 stoichiometry (Figure b). A long oligopyridyl ligand with both pyridyl and aryl central cores can form an extended multicavity cage upon assembly with Pd II . This multicavity cage shows the same selectivity as the individual cages: cisplatin can be bound in the terminal cavities via H‐bonding with the internal pyridyl lone pairs, whereas triflate ions reside in the central cavity, favorably interacting with the mildly acidic internal C−H bonds.…”