Remote stereocentres do not disrupt the stereochemical coupling in homochiral [M2L3] helicates and [M4L6] tetrahedra

Despite the use of achiral ligands, the vast majority of metallosupramolecular assemblies containing octahedral tris-bidentate metal centres show strong stereochemical communication between metal centres, generally resulting in homochiral assemblies even though they are statistically disfavoured. Here we show that when resolved stereocentres are attached to the central part of a quaterpyridine ligand, the stereochemical coupling from this centre is insufficient to disrupt the strong stereochemical communication between metal centres in both [M2L3] helicates and [M4L6] tetrahedra.

Homochiral Porous Metal-Organic Polyhedra with Multiple Kinds of Vertices

Metal-organic polyhedra featuring non-Archimedean/Platonic architectures with multiple kinds of vertices have aroused great attention for their fascinating structures and properties but are yet challenging to achieve. Here, we report a combinatorial strategy to make such nonclassic polyhedral cages by combining kinetically labile metal ions with non-planar organic linkers instead of the usual only inert metal centers and planar ligands. This facilitates the synthesis of an enantiopure twisted tetra(3-pyridyl)-based TADDOL (TADDOL = tetraaryl-1,3-dioxolane-4,5-dimethanol) ligand (L) capable of binding Ni(II) ions to produce a regular convex cage, Ni₆L₈, with two mixed metal/organic vertices and three rarely reported concave cages Ni₁₄L₈, Ni₁₈L₁₂, and Ni₂₄L₁₆ with three or four mixed vertices. Each of the cages has an amphiphilic cavity decorated with chiral dihydroxyl functionalities and packs into a three-dimensional structure. The enantioselective adsorption and separation performances of the cages are strongly dependent on their pore structure features. Particularly, Ni₁₄L₈ and Ni₁₈L₁₂ with wide openings can be solid adsorbents for the adsorptive and solid-phase extractive separation of a variety of racemic spirodiols with up to 98% ee, whereas Ni₆L₈ and Ni₂₄L₁₆ with smaller pore apertures cannot adsorb the racemates. The combination of single-crystal X-ray diffraction analysis of the host-guest adduct and GCMC simulation indicates that the enantiospecific recognition capabilities originate from the well-organized chiral inner sphere as well as multiple interactions within the chiral microenvironment. This work therefore provides an attractive strategy for the rational design of polyhedral cages, showing geometrically fascinating structures with properties different from those of classic assemblies.

Multifunctional chiral cationic porous organic polymers: gas uptake and heterogeneous asymmetric organocatalysis

Chiral porous organic polymers are characterized by robust, non-toxic and recyclable properties. Therefore, compared with small molecular catalysts, they have attracted much attention in the field of heterogeneous asymmetric organic catalysis.

Thiol-yne Click Post-Modification for the Synthesis of Chiral Microporous Organic Networks for Chiral Gas Chromatography

Microporous organic networks (MONs) have shown great potential in diverse domains recently. However, the application of MONs in chiral separation or catalysis has been largely lagged due to the lack of chiral MONs and the challenge to synthesize chiral MONs. Here we report a facile thiol-yne click strategy to post-synthesize chiral MONs for the first application in chiral gas chromatography. Three chiral MONs with different chiral centers were rationally designed and synthesized to fabricate their capillary columns for gas chromatographic resolution of various chiral compounds with better resolution than three commercial chiral capillary columns. These results show the great potential of the thiol-yne click strategy for constructing newly chiral MONs and their application in chiral separation.

Chiral covalent organic frameworks: design, synthesis and property

Owing to the unique structural features and facile tunability of the subcomponents and channels, chiral COFs show great potential in heterogeneous catalysis, enantioselective separation, and recognition.

Pyrrolidine-based chiral porous polymers for heterogeneous organocatalysis in water

The “bottom-up” reticulation of chiral pyrrolidine into POPs for heterogeneous organocatalysis in pure water.

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

Achiral polymeric supports can have important positive effects on the activity, stability and selectivity of supported chiral catalysts.

Polymer-immobilized chiral catalysts

This review illustrates the current strategies and potential of polymer-immobilized chiral catalysts for highly enantioselective asymmetric synthesis.