Truncated Sierpiński Triangular Assembly from a Molecular Mortise–Tenon Joint

Abstract

The amalgamation of different components into a giant and intricate structure that makes quantitative and spontaneous assembly through molecular design is indispensable but challenging. To construct novel metallo-supramolecular architectures, here we present an architectural design principle based on multicomponent self-assembly. Using a carefully designed hexatopic terpyridine-based metallo-organic ligand (MOL), [RuTK], we report on the formation of supramolecular trapezoid Zn[RuTK]V, hollow hexagon Zn[RuTK]K, and giant star-shaped supramolecule Zn[RuTK][RuXV], all of which were assembled by one-pot, nearly quantitative assembly of [RuTK] with the ditopic 60°-directed bisterpyridine V, tetrakisterpyridine K, and MOL [RuXV], respectively. The complementary ligands were selected on the basis of the size- and shape-fit principles, actually similar to the mortise-tenon joint that aligns and locks the two complementary wood components. This strategy is expected to open the door to sophisticated designer supramolecules and nonbiological materials. The multivalent connections within the mutual ligands give rise to the formation of stable assemblies, which are unambiguously characterized by NMR, ESI-MS, TWIM-MS, and TEM analyses.

Construction of Macromolecular Pinwheels Using Predesigned Metalloligands

“…Key metalloligands L1 and L2 with four uncomplexed free terpyridines are featured in a truncated rhombus bound to a V-directed tenon. They were assembled with Zn 2+ ions to introduce a discrete pinwheel-shaped star trigon P1 and pentagram P2 (the trimer and pentamer product, respectively), attributed to the intramolecular mortise–tenon joint . Both P1 and P2 were composed of rhombuses by utilizing vertex connectivity, and possess a triangle and pentagon, respectively, in the center.…”

“…They were assembled with Zn 2+ ions to introduce a discrete pinwheel-shaped star trigon P1 and pentagram P2 (the trimer and pentamer product, respectively), attributed to the intramolecular mortise−tenon joint. 27 Both P1 and P2 were composed of rhombuses by utilizing vertex connectivity, and possess a triangle and pentagon, respectively, in the center. More importantly, a larger and more complicated pinwheel-shaped hexagram P3 (a hexamer product) could be generated via the coordination of an octaterpyridine metalloligand (L3) and Zn 2+ ions (Scheme 1).…”

Multicomponent Metallo-Supramolecular Nanocapsules Assembled from Calix[4]resorcinarene-Based Terpyridine Ligands

“…Indeed, the self-selective coordination approaches provided facile access to construction of discrete well-defined heteroleptic metallo-supramolecules through multicomponent self-assembly, producing various outputs such as prisms, − trefoil knots, , molecular muscles, − shuttles, − and catalytic machinery. − Among them, 2,2′:6′,2″-terpyridine (tpy) ligands have recently attracted considerable attention because of their adjustable coordination lability and excellent solubility to maintain homogeneity in self-assembly. , Due to the pseudo-octahedral coordination geometry of <tpy–M II –tpy>, organic molecules, such as carbazole, porphyrin, adamantane, , and crown ethers, − are commonly selected as a core to create proper geometric angles. Robust <tpy–Ru II –tpy> derivatives are often functionalized to afford a variety of metalloligands in a stepwise manner, so as to suppress formation of mismatched assemblies. − To lessen the synthetic burden, we have demonstrated that the tpy ligand modified by 2,6-dimethoxyphenyl substituents at 6,6″-tpy positions can spontaneously form a heteroleptic complex with an unsubstituted tpy ligand in the presence of Cd II ions . Given this molecular self-recognition, the quantitative self-assembly of a number of 2D and 3D metallo-supramolecular architectures has been successfully realized. , To further explore self-assembly behavior of the 4-fold symmetric cavitand-based tpy ligand with complementary counterparts, herein we focus our investigations on the construction of multicomponent nanocapsules bearing calix[4]­resorcinarenes.…”

Conformational Regulation of Multivalent Terpyridine Ligands for Self-Assembly of Heteroleptic Metallo-Supramolecules

“…Among them, a variety of multivalent 2,2′:6′,2″-terpyridine (tpy)-based ligands can be obtained by palladium-catalyzed cross-coupling reactions and serve as subcomponents for self-assembly of giant metallo-supramolecules . In the supramolecular chemistry of metal–tpy complexes, a stepwise approach is commonly used to prepare predesigned metalloligands to eliminate mismatched assemblies during self-assembly. , Nevertheless, toward elevating the degree of molecular self-sorting, we have demonstrated that an equimolar mixture of 6,6″-di­(2,6-dimethoxy­phenyl)­tpy and unsubstituted tpy ligands can afford a sole heteroleptic complex upon addition of Cd II ions under ambient conditions . The complementary ligand pair offers facile access to preparation of discrete metallomacrocycles as well as metallocages via multicomponent self-assembly. , …”