Hexameric Lanthanide–Organic Capsules with Tertiary Structure and Emergent Functions

Abstract

Biological macromolecules always function through a collective behavior of the aggregated constituents, which usually are self-assembled together via noncovalent interactions. Likewise, artificial supramolecular assemblies, whose properties and functions are mainly derived from their primary and secondary structures, may also aggregate into high-order architectures with emergent functions not available on the individual components. Here we report the first example of an insulin-like hexamerization of lanthanide triple helicates toward a 4 nm diameter hexameric capsule via consecutive metal-directed and anion-directed assembly processes. Hierarchical chiral-sorting self-assembly endows hexamers with aggregation-induced stability and emission enhancement. Furthermore, emergent guest-encapsulation function and enantioselectivity toward terpene drugs have been realized in the late-formed central cavity of the hexamers. This study not only provides a feasible strategy for constructing sophisticated and multifunctional lanthanide−organic materials but also sheds some light on the self-assembly processes in nature.

Metallosupramolecular cages: from design principles and characterisation techniques to applications

“…15 Nevertheless, the number of lanthanide-based cages is increasing and various architectures including M 3 L 2 , tetrahedra, cubes and more recently, a hexameric cage self-assembled from helicates have been reported. [15][16][17] The counterion of the metal salt can also influence the self-assembly process as a template (see Section 2.2.1) and recently, Reek and co-workers reported halide impurities in metal salts play a catalytic role in the self-assembly of a variety of Pd II , Pt II and Ni II cages; 18 these impurities are proposed to reduce the energy required to convert kinetically trapped species to the thermodynamically favoured cage.…”

Transformation networks of metal–organic cages controlled by chemical stimuli

“…13a ). 121 They first utilised C 2 -symmetric ligand 132 with tridentate binding sites in combination with Eu III (OTf) 3 to form Eu III 2 132 3 triple helicate 133. Surprisingly, replacing the triflate anions by perchlorate yields another species that predominates at higher concentrations.…”

Mesoporous silica nanoparticle-embedded lanthanide organic polyhedra for enhanced stability, luminescence and cell imaging

“…Due to the intrinsic optical and magnetic properties of lanthanide ions stemmed from their shielded 4f electrons, 1,2 lanthanide-containing compounds are quite fascinating due to their potential applications in luminescent displays, [3][4][5][6][7][8][9][10][11] bioimaging, [12][13][14][15][16][17] sensing, [18][19][20][21][22][23][24][25][26] catalysis, [27][28][29][30] single-molecular magnets, [31][32][33][34] MRI contrast agents, [35][36][37][38][39][40] and upconversion materials, [41][42][43][44][45] etc. 46 Particularly, the characteristics of lanthanide-containing compounds, [47][48][49] such as sharp line-like and ligand-independent emission bands, long lifetimes, and large Stokes/anti-Stokes shifts, endow their ...…”