Fine‐Tuning of Chiral Microenvironments within Triple‐Stranded Helicates for Enhanced Enantioselectivity

Abstract

Here we report the formation of an unexpected and unique family of chiral helicates.C rystal structures showt hat these triple-stranded Zn II 2 L 3 complexes are held together by subcomponent assembly of axially chiral diamine-functionalized 1,1'-biphenol ditopic with 2-formylpyridine and Zn II . Specifically,t he molecular helicity of the complexes can be controlled by the absolute configurations of the bimetallic vertices,which has been shown to be homoconfiguration (DD) or mesomeric configuration (DL), depending critically on the bulky groups and length of the spacers.F ascinatingly,i nt his system we can engineer the space-restricted chiral microenvironments with varied polar and apolar moieties,w hich profoundly influence the binding affinities and chiral discrimination properties of the helicates,l eading to highly enantioand helix-sense-selective recognition for chiral amino alcohols (up to 9.35). This work reveals the transformation of singlemolecule chirality to global supramolecular chirality within well-defined helicates and demonstrates that their chiral discrimination are highly dependent on the superior microenvironments.

Nitro group and K+-based secondary building units for the self-assembly of 3D coordination polymers built on dinuclear dianionic helicate connectors

“…Triply stranded dimetallic helicates 1 have received considerable attention as they can offer interesting physicochemical properties such as chirality, 2 act as hosts for molecules, 3 magnetism, 4 and luminescence. 5 The ligand design is fundamental for obtaining helicate complexes; therefore, two approaches can be followed: a designer approach in which a polydentate multinucleated ligand can be synthesized (investing serious time and effort) or a self-assembly approach, in which in situ formation of the ligand and the helicate complex occurs, due to the right match of subcomponents, e.g., ligands bite angle, metal ion geometry, and angle between coordination pockets.…”

“…Triply stranded dimetallic helicates 1 have received considerable attention as they can offer interesting physicochemical properties such as chirality, 2 act as hosts for molecules, 3 magnetism, 4 and luminescence. 5…”

Hierarchical subcomponent self-assembly of covalent triple-stranded complexes with 3d–4f vertices: luminescence and magnetic properties

“…A myriad of diverse metallo-supramolecular compounds with sophisticated structures and fascinating functions, including, but not limited to, macrocycles, [10][11][12] helicates, [13][14][15] grids, 16,17 catenanes, 18 rotaxanes, 19 and metal-organic polyhedra, [20][21][22][23] have been successfully fabricated by the subcomponent self-assembly approach. Besides these types of structures, there is another type of structure composed of a discrete covalent organic skeleton and metal ions, namely discrete covalent metallo-supramolecular architectures, in which the metal ions are located at the vertices or panels of the covalent organic skeleton.…”