Evolution of Multicomponent [Pd2ABCD] Cages

Abstract

Synthetic supramolecules, inspired by biological hosts, catalysts and machines, promise to find application in sustainable synthesis, separation, energy conversion and medicine. However, the implementation of multiple functionalities within distinct self- assembled structures still poses considerable challenges. In particular metal-mediated assemblies are difficult to form from multiple chemically different building blocks without falling into narcissistic self-sorting or a statistical mess. Here we report a systematic series of integratively self-assembled heteroleptic cages in which two square-planar PdII cations are bridged by four chemically different bis-pyridyl ligands A, B, C and D via a collection of synergistic effects to form a single isomer of lantern-shaped cage [Pd2ABCD] as exclusive product. This ultimate self-sorting goal, forming just one out of 55 possible structures, is reached under full thermodynamic control and can be realized progressively (by combining heteroleptic progenitors such as [Pd2A2C2] with [Pd2B2D2]), directly from ligands and PdII cations, or most impressively by mixing all four corresponding homoleptic cages. Structural and mechanistic details were comprehensively examined by NMR and mass spectrometry and nine single crystal X-ray structures. The rational design of complex multicomponent assemblies, formed in high yield under thermodynamic control, allows to incorporate different chemical moieties in a modular approach and advance the application level of functional nanosystems.

Reactions in Endohedral Functionalized Cages

“…Very recently, Clever demonstrated the synthesis of a [Pd 2 L 1 L 2 L 3 L 4 ] cage by a combination of ligand shape complementary, strain balance and inter ligand CÀ H-π interaction. [98] In addition to the bite angle control of the building blocks, heteroleptic cages have also been shown to be synthesized via ligand interaction such as steric bulk or hydrogen bonding interactions. [99,100] Zhang used such an approach to design endohedral-functionalized [Pd 2 L 1 2 L 2 1 L 3 1 ] cages.…”

Metal-Peptidic Cages – Helical Oligoprolines Generate Highly Anisotropic Nanospaces with Emergent Isomer Control

“…the C-terminus is distinct from the N-terminus). As such, while our cage is homoleptic, [58][59][60][61][62][63][64][65] there are four distinct cage isomers which can form (Figure 4a): where the C-termini are all aligned and sit on one end (i.e. bind one palladium(II) ion) of the cage (denoted CCCC), where three Ctermini and one N-terminus lie at one end (denoted CCCN), and two cases where two C-termini and two N-termini are at each end, either with C-termini cis or trans to each other across the palladium(II) centre (CCNN and CNCN respectively).…”

A Lantern‐Shaped Pd(II) Cage Constructed from Four Different Low‐Symmetry Ligands with Positional and Orientational Control: An Ancillary Pairings Approach

“…[16] Of all these approaches, the greatest singular success has been reported by Clever and co-workers, who successfully synthesised a number of heteroleptic cages with four different ligands. [17] Their approach relied upon favourable CH-π interactions between two of the ligands (e.g. green and blue, Figure 1F) driving these into a cis orientation with respect to one another, while the other two ligands (yellow and red) have geometric complementarity to the first two.…”