ABSTRACT
Spontaneous formation of the heteroleptic cadmium(II) bis(terpyridine) complex under ambient conditions can be achieved by a combination of 6,6''-di(2,6-dimethoxylphenyl)-substituted and unsubstituted terpyridine-based ligands. Building on this dynamic heteroleptic complexation, diverse metallo-supramolecular macrocycles and cages were readily assembled in quantitative yields from the predesigned multicomponent systems. The complementary ligation reinforced self-recognition to facilitate the shape-dependent self-sorting of a four-component dynamic library into two well-defined parallelograms. In addition, the subtle lability difference between homoleptic and heteroleptic complexes led to the site-selective CdII -ZnII transmetalation in the Sierpinski triangle. Facile construction of a dodecanuclear tetrahedral metallocage was also realized by using two self-recognizable tritopic building blocks. The photophysical study of the metallo-supramolecules assembled from the d10 metal ions revealed intense ligand-based photoluminescence in solution. The self-assembly strategy described here provides an efficient methodology for building pre-programmable, sophisticated supramolecular architectures furnished with photoactivity.
ABSTRACT
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.
ABSTRACT
Predesigned complementary complexation of two 2,2':6',2â³-terpyridine-based ligands was established by installing 2,6-dimethoxyphenyl substituents at the terpyridyl 6,6â³-positions, which provided ancillary ion-dipole interactions in the coordination process and extra π-stacking stabilization in the resultant heteroleptic complex. The high-fidelity self-recognition ligation afforded facile access to the quantitative self-assembly of multicomponent triangle [Cd6L(3)3L(4)3] and ditrigon [Cd15L(3)6L(5)3] (that is, a hexagon with six 120° angles and two alternating edge lengths). It was found that the linear 6,6â³-substituted ditopic motif (L(3)) would be directed by the ligand geometry of L(5) to selectively incorporate into the parallel homoleptic connections in the bilayered framework.
ABSTRACT
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).
