Facile synthesis of multicomponent heterobimetallic metallomacrocycles through selective metal-ligand coordination.

Three heterobimetallic metallomacrocycles were readily assembled through either a stepwise or a one-pot protocol by selective complexation of ZnII ions and PdII or PtII acceptors with the predesigned ligands possessing one 60°-bent bisterpyridine and two mono- or bis-pyridines. In the multicomponent self-assembly, the preorganized ZnII-terpyridine metallo-triangle led to the formation of the exterior macrocycles.

Stimuli-Responsive Supramolecular Gels Constructed by Hierarchical Self-Assembly Based on Metal-Ligand Coordination and Host-Guest Recognition.

Metal-ligand coordination and host-guest recognition are introduced into the hybrid system in order to prepare supramolecular gels, which can be responsive to multiple external stimuli such as metal ions, competitive guest/host molecules, and oxidants. To this end, the triangular terpyridine-based metallocycles functionalized with 1-adamantyl and ferrocenyl groups are constructed through self-assembly, and further used as supramolecular cross-linkers for gelation of ß-CD-containing copolymers. Their gelation and stimuli-response tests are discussed, and an application of the metallotriangles for serving as supramolecular glue is demonstrated through a series of adhesion experiments. This approach enables facile access to construction of multifunctional metallosupramolecules as well as functional hybrid materials.

Metal ion-modulated self-assembly of pseudo-suit[3]anes using crown ether-based terpyridine metalloprisms.

Two hexanuclear metalloprisms possessing three dibenzo[24]crown-8 units were generated in quantitative yields by complexation of the predesigned tetratopic 2,2':6',2''-terpyridine ligand (T) with CdII and ZnII ions, respectively. The prismatic hosts were subsequently self-assembled with the trifunctional guest molecule (TriG) containing dibenzylammonium ions to afford the corresponding metallo-supramolecular pseudo-suit[3]anes. It was serendipitously found that the host-guest inclusion rates could be modulated by the subtle dynamic difference in metal-ligand frameworks, finally leading to a selective encapsulation event in the presence of both metallo-suits.

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

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)).

Self-assembly of triangular metallomacrocycles using unsymmetrical bisterpyridine ligands: isomer differentiation via TWIM mass spectrometry.

Three unsymmetrical, 60°-bended bisterpyridine ligands with varying phenylene spacer lengths have been synthesized via the Suzuki-Miyaura coupling reactions. Their self-assembly processes were found to be strongly dependent on the ligand geometry. Upon complexation with Zn(II) ions, only 2,4''-di(4'-terpyridinyl)-1,1':4',1''-terphenyl underwent self-selection to give a trinuclear metallomacrocycle with perfect heteroleptic connectivity and the other two afforded a mixture of constitutional isomers. The metallosupramolecular assemblies were characterized by NMR spectroscopy, electrospray mass spectrometry (ESI MS), and single-crystal X-ray diffraction. In particular, the identification of isomeric architecture was accomplished using tandem mass spectrometry (MS(2)) coupled with traveling wave ion mobility mass spectrometry (TWIM MS).