A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (−) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90–99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.

The template-directed strategy is a powerful method to construct porphyrin nanorings with high complexities, wherein metalloporphyrin precursors pre-organize via supramolecular interactions of the porphyrin or its central metal with a carefully selected template, and then react with each other to deliver a final cyclic multiporphyrin structure. In this article, we review the recent breakthroughs in the template-directed synthesis methods and new structures of porphyrin or metalloporphyrin nanorings, as well as their applications in host–guest chemistry and artificial light-harvesting.

We present the formation of a series of chiral metallacycles and metallacages by the use of a BINOL-derived dicarboxylate as a donor that is capable of affording a variety of coordination angles between its two Lewis basic sites. Two squares, two rhomboids, two tetragonal prisms, and one hexagonal prism were successfully formed when the chiral dicarboxylate donor self-assembled with one of four ditopic Pt(II) complexes, including two bimetallic 180° Pt-based acceptors, a 120° bimetallic Pt-based acceptor, and a 90° mononuclear Pt-based acceptor. Their structures were well characterized by 31P{1H} NMR, ESI-MS, CD, and optical rotation analyses.

Hierarchical self-assembly centered on metallacyclic scaffolds greatly facilitates the construction of mechanically interlocked structures. The formation of two [3]catenanes and one [4]molecular necklace is presented by utilizing the orthogonality of coordination-driven self-assembly and crown ether-based cryptand/paraquat derivative complexation. The threaded [3]catenanes and [4]molecular necklace were fabricated by using ten and nine total molecular components, respectively, from four and three unique species in solution, respectively. In all cases single supramolecular ensembles were obtained, attesting to the high degree of structural complexity made possible via self-assembly approaches.

We describe the fabrication of a suite of flexible porphyrin cages and nanorings from a simple tetraalkene-derived zinc porphyrin monomer via a highly efficient template-directed strategy. The zinc porphyrin monomers were preorganized together by coordination with N atoms of multidentate ligands. Subsequent one-step olefin metathesis furnished a bisporphyrin cage, a triporphyrin nanoring, and a hexaporphyrin nanoring. In the case of the hexaporphyrin nanoring, 24 terminal olefins from six porphyrin monomers reacted with each other to form 12 new double bonds, delivering the final product. The triporphyrin and hexaporphyrin nanorings were further employed as hosts to encapsulate C60 and C70.

The formation of catenated systems can be simplified greatly if one or more rings are generated via self-assembly. Herein we exploit the orthogonality of coordination-driven self-assembly and crown-ether host–guest complexation to obtain a [4]molecular necklace and a [7]molecular necklace based on a well-developed recognition motif of 1,2-bis(pyridinium)ethane/dibenzo[24]crown-8. By adapting the bis(pyridinium) motif into the backbone of a donor building block, the resulting semirigid dipyridyl species can serve both as a structural element in the formation of metallacycles and as a site for subsequent host–guest chemistry. The pseudolinear nature of the donor precursor lends itself to the formation of triangular and hexagonal central metallacycles based on the complementary acceptor unit used. This exemplary system organizes up to 18 molecules from three unique species in solution to afford a single supramolecular ensemble.

A main chain-type polyrotaxane was fabricated by employing a one-pot synthesis strategy from a pseudorotaxane monomer and an end-capping agent. Based on this polyrotaxane, a controllable molecular machine was furnished upon the external acid/base stimuli, and a reversible transition between linear and cross-linked polyrotaxane was achieved by the successive addition of [PdCl2(PhCN)2] and PPh3.

Coordination-driven self-assembly can be used to construct metallacycles decorated with saccharide functionalities by combining organoplatinum acceptor building blocks with glycosylated dipyridyl donors. We describe here the synthesis of a suite of donors encoded with 120° directionality. The 1,3-bis(pyridin-4-ylethynyl)benzene cores contain one of four pendant saccharide groups, resulting in a glucose-, galactose-, mannose-, and lactose-variant. The angularity of these donors makes them suitable for the self-assembly of [2 + 2] rhomboids and [3 + 3] hexagons containing two and three saccharide groups on combination with a 60 or 120° acceptor, respectively. The synthesis and characterization of eight such metallacycles are described, supported by multinuclear NMR and electrospray mass spectrometry data that confirm clean, highly symmetric products with the expected stoichiometries of formation. This work illustrates the use of coordination-driven self-assembly to obtain nanoscopic metallacycles with biologically relevant functionalities in high yields and facile synthetic methods.

We describe the formation of a suite of [3]catenanes via multicomponent coordination-driven self-assembly and host–guest complexation of a rectangular scaffold comprising a 90° Pt-based acceptor building block with a pseudorotaxane bis(pyridinium)ethane/dibenzo-24-crown-8 linear dipyridyl ligand and three dicarboxylate donors. The doubly threaded [3]catenanes are formed from a total of 10 molecular components from four unique species. Furthermore, the dynamic catenation process is reversible and can be switched off and on in a controllable manner by successive addition of KPF6 and 18-crown-6, as monitored by 1H and 31P NMR spectroscopy.

Piperazine derivatives are important intermediates in organic synthesis and useful building blocks in pharmaceutical and fine chemical industries. Currently available synthetic routes for these heterocyclic compounds have limited scope owing to the harsh reaction conditions, low yields, and multistep process. Herein, we reported a practical method for synthesis of alkyl-, alcohol-, amine-, and ester-extended tosylpiperazines under mild conditions with moderate to high yields. This protocol exhibits potential applicability in the synthesis of pharmaceuticals and natural products because of the operational simplicity and the conveniently available reactants. On the basis of the experimental and theoretical results, a plausible mechanism of aliphatic nucleophilic substitution (SN) in the cyclization has been postulated and evidence for the formation of a six-membered ring has also been confirmed by means of density functional theory (DFT) calculations.

The template-directed strategy is a powerful method to construct porphyrin nanorings with high complexities, wherein metalloporphyrin precursors pre-organize via supramolecular interactions of the porphyrin or its central metal with a carefully selected template, and then react with each other to deliver a final cyclic multiporphyrin structure. In this article, we review the recent breakthroughs in the template-directed synthesis methods and new structures of porphyrin or metalloporphyrin nanorings, as well as their applications in host–guest chemistry and artificial light-harvesting.

A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (−) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90–99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.