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.

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.…”

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.…”

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 ...…”