Transition metals with specific coordination geometries have been employed for the rational design and construction of highly ordered supramolecular structures. [1] We have shown that the simple combination of the square-planar coordination geometry of palladium (908 bond angle) with pyridinebased bridging ligands leads to the quantitative self-assembly of nanometer-sized, discrete organic frameworks [2] such as ªmolecular squaresº [3,4] and an adamantanoid cages.[5] Here we report the efficient self-assembly of nanometer-sized macrotricycles from ten small components. Treatment of [Pd(NO 3 ) 2 (en)] (1) with the tripyridylmethane 2 [6] results in self-assembly to the nanometer-sized macrotricyclic framework 3, in which four ligand molecules are held together by six metal ions (Scheme 1). A similar ten-component self-assemScheme 1. Synthesis of 3.bly process leads to formation of the nanoscale macrotricycle 5 from 1 and the triazine-based ligand 4 (Scheme 2). Recently, there were a few reports of the metal-directed self-assembly of nanometer-sized macrocycles. [7,8] However, their structures Scheme 2. Synthesis of 5.have often been deduced from spectroscopic data. [8] In contrast, the structures of nanometer-sized macrotricycles 3 and 5 were unambiguously determined by X-ray crystallographic analyses.Ligand 2 was suspended in an aqueous solution of 1 (1.5 equiv), and the mixture was heated at 70 8C.[9] After 40 min a colorless clear solution was obtained. Analysis by NMR spectroscopy of the solution obtained by carrying out the reaction in D 2 O showed the quantitative self-assembly of 1 and 2 to form a single product. The addition of aqueous NaClO 4 (1m) resulted in precipitation of 3´12 ClO 4 in 85 % yield. When ethanol/water was employed as the solvent, the product was obtained from the solution directly as a NO À 3 salt by cooling to about 5 8C for several days. The elemental analyses agreed with the empirical formulas of 3´12 ClO 48 H 2 O and 3´12 NO 3´1 2 H 2 O. The NMR spectra of 3 contain only one acetoxyl signal (

A luminescent supramolecular chiral Au16 ring with 4.822 nm perimeter that self-assembled from a tetrameric array of achiral Au2 units is described. Intra- and intermolecular Au...Au interactions play an important role in directing its chiral self-assembly.