Facile Self‐Assembly of Metallo‐Supramolecular Ring‐in‐Ring and Spiderweb Structures Using Multivalent Terpyridine Ligands

Abstract

A series of metallo-supramolecular ring-in-ring structures was generated by assembling Cd(II) ions and the multivalent terpyridine ligands (L(1-3)) composed of one 60°-bent and two 120°-bent bis(terpyridine)s with varying alkyl linker lengths. The mechanistic study for the self-assembly process excluded an entropically templated pathway and showed that the intramolecularly complexed species is the key intermediate leading to ring-in-ring formation. The next-generation superstructure, a spiderweb, was produced in quantitative yield using the elongated decakis(terpyridine) ligand (L(5)).

Vertical Assembly of Giant Double‐ and Triple‐Decker Spoked Wheel Supramolecular Structures

“…Then S 1 was generated as afaint yellow solid in 96 %y ield. [16,19] Similarly,t he 1 HNMR spectra of S 1 and S 3 showed distinct patterns and all of the peaks were fully assigned (see the Supporting Information). 1 HNMR spectra of ligands L 2 and T and complex S 2 are shown in Figure 2a.Inthe aromatic region of the NMR spectrum of ligand L 2 ,t wo distinguishable sets of tpy resonances represented by two characteristic singlets at 8.71 and 8.60 ppm are observed, which were assigned to tpyH 3',5' peaks;inthe non-aromatic region, one triplet and one singlet appeared at 4.28 and 3.74 ppm in a1:3 integration ratio,which were attributed to methylene and methoxy groups.F or the complex S 2 ,the 1 HNMR spectrum exhibited broad resonance peaks presumably owing to the low tumbling motion on the NMR time scale for the large supramolecular architecture.…”

“…[13] Much effort has also been devoted to construct complicated higher-order motifs through terpyridinyl ligand-metal coordination interactions.F or example,Newkome and co-workers reported the self-assembly of the first generation Sierpiń ski triangle fractal and hexagonal gasket. [15] Furthermore, aw ell-defined spiderweb-like ring-in-ring-in-ring superstructure was successfully synthesized through self-assembly of the multivalent terpyridine ligands with metal ions by Chan et al [16] It is worth noting that the above-mentioned superstructures were constructed by extending the structure in a2D plane,just like the concentric ring system (Figure 1a). [15] Furthermore, aw ell-defined spiderweb-like ring-in-ring-in-ring superstructure was successfully synthesized through self-assembly of the multivalent terpyridine ligands with metal ions by Chan et al [16] It is worth noting that the above-mentioned superstructures were constructed by extending the structure in a2D plane,just like the concentric ring system (Figure 1a).…”

Vertical Assembly of Giant Double‐ and Triple‐Decker Spoked Wheel Supramolecular Structures

“…This could be ascribed to the highly shielded environment from the proximity of two < tpy–Cd 2+ –tpy > connections and such a result strongly supported the stacking hexagon formation. [16,19] Similarly, the 1 H NMR spectra of S 1 and S 3 showed distinct patterns and all of the peaks were fully assigned (see the Supporting Information). …”

“…[14] Li and co-workers prepared two species of concentric hexagons using tetratopic pyridine and terpyridine ligands coordinating with metal ions. [15] Furthermore, a well-defined spiderweb-like ring-in-ring-in-ring superstructure was successfully synthesized through self-assembly of the multivalent terpyridine ligands with metal ions by Chan et al [16] It is worth noting that the above-mentioned super-structures were constructed by extending the structure in a 2D plane, just like the concentric ring system (Figure 1a). Herein, we introduce the 3D double- or triple-decker hexagon system by vertically extending the plane spoked wheels [17] into 3D space (Figure 1b).…”

Self-assembly of a supramolecular hexagram and a supramolecular pentagram

“…Recent noteworthy accomplishments with tpy-based architectures include Sierpinski hexagonal gasket, spoked wheel, ring-in-ring and cage-like macromolecules1617181937383940414243. Because of the ligand flexibility and deviation from the coordination geometry predicated by thermodynamic or kinetic stabilities38 of several possible coordinated isomeric products, the assembly might produce a mixture and/or polymer, especially when targeting large and discrete assemblies (molecular weight>10,000 Da).…”