Chiral Assembly and Recognition of Seven Copper (II) Coordination Polymers from Tartaric Acid Derivative Ligands

A pair of enantiomeric ligands, (2R,3R)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((R,R)-L) and (2S,3S)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((S,S)-L), are designed and synthesized. Seven copper (II) coordination polymers {[Cu((R,R)-L)Br 2 (THF)]·CH 3 CN} n ( 1a ) and {[Cu((S,S)-L)Br 2 (THF)]·CH 3 CN} n ( 1b ), {[Cu((R,R)-L)Cl 2 (THF)]·CH 3 CN} n ( 2a ) and {[Cu((S,S)-L)Cl 2 (THF)]·CH 3 CN} n ( 2b ), {[Cu((R,R)-L)(NO 3 ) 2 (CH 3 CN)]} n ( 3a ) and {[Cu((S,S)-L)(NO 3 ) 2 (CH 3 CN)]} n ( 3b ), {[Cu((R,R)-L) 2 (CH 3 CN) 2 ](ClO 4 ) 2 ·3CH 3 CN} n ( 4 ) were obtained through the assemblies with CuBr 2 , CuCl 2 ·2H 2 O, Cu(NO 3 ) 2 ·3H 2 O, Cu(ClO 4 ) 2 ·6H 2 O, respectively. Single-crystal X-ray diffraction and circular dichroism analysis demonstrate that 1a-3a , 1b-3b have a mono chiral one-dimensional (1D) chain-like spiral structure, while 4 have 1D chain-like structure whose metal centers have chiral propeller coordination environment. Ligand structure, anions and solvent systems have a regulatory effect on the formation of chiral helical structure. Further investigation has proved that 1a can be used as circular dichroism spectrum probe for monitoring L-/D-cysteine and L-/D-penicillamine configuration and concentration in aqueous media based on ligand interchange mechanism.

Chiral Metal-Organic Frameworks

In the past two decades, metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) assembled from metal ions or clusters and organic linkers via metal-ligand coordination bonds have captivated significant scientific interest on account of their high crystallinity, exceptional porosity, and tunable pore size, high modularity, and diverse functionality. The opportunity to achieve functional porous materials by design with promising properties, unattainable for solid-state materials in general, distinguishes MOFs from other classes of materials, in particular, traditional porous materials such as activated carbon, silica, and zeolites, thereby leading to complementary properties. Scientists have conducted intense research in the production of chiral MOF (CMOF) materials for specific applications including but not limited to chiral recognition, separation, and catalysis since the discovery of the first functional CMOF (i.e., d- or l-POST-1). At present, CMOFs have become interdisciplinary between chirality chemistry, coordination chemistry, and material chemistry, which involve in many subjects including chemistry, physics, optics, medicine, pharmacology, biology, crystal engineering, environmental science, etc. In this review, we will systematically summarize the recent progress of CMOFs regarding design strategies, synthetic approaches, and cutting-edge applications. In particular, we will highlight the successful implementation of CMOFs in asymmetric catalysis, enantioselective separation, enantioselective recognition, and sensing. We envision that this review will provide readers a good understanding of CMOF chemistry and, more importantly, facilitate research endeavors for the rational design of multifunctional CMOFs and their industrial implementation.

Structural, thermal and topological characterization of coordination networks containing flexible aminocarboxylate ligands with a central biphenylene scaffold

Flexible aminocarboxylate ligands have been used to construct coordination networks containing Zr, Zn and Cd featured by different dimensionalities and topologies.

Chiral induction in a pcu-derived network from achiral precursors

The first chiral network derived from a classic pcu net has been rationally prepared from achiral precursors.

A water-stable homochiral luminescent MOF constructed from an achiral acylamide-containing dicarboxylate ligand for enantioselective sensing of penicillamine

A water-stable homochiral luminescent MOF was obtained by spontaneous symmetry-breaking crystallization from achiral precursors; it exhibits enantioselective sensing of d/l-Pen.

Evaluating the component contribution to nonlinear optical performances using stable [Ni4O4] cuboidal clusters as models

Cuboidal [Ni₄O₄]-based clusters are systematically studied with the purpose of evaluating the component contribution to the overall nonlinear optical performances.

Chiral metal–organic frameworks constructed from four-fold helical chain SBUs for enantioselective recognition of α-hydroxy/amino acids

Three chiral 3D metal–carboxylate frameworks have been successfully synthesized, featuring four-fold helical metal chains as SBUs. Co-MOFs could recognize enantio-selectively α-hydroxy/amino acids by the change of CD signals.

A second-order nonlinear optical material with a 5-fold interpenetrating diamondoid framework based on two achiral precursors: spontaneous resolution to absolute chiral induction

A pair of enantiomeric Zn(ii) complexes have been synthesized through spontaneous resolution. Fortunately, the handedness of bulk crystals can be controlled by using a chiral induction agent. Notably, they display strong SHG response.

Synthesis and structural diversity of d10 metal coordination polymers constructed from new semi-rigid bis(3-methyl-1H-pyrazole-4-carboxylic acid)alkane ligands

Three isomeric ligands, and four d¹⁰ metal CPs were synthesized, varying from 1D to 2D, together with achirality to chirality variation.

Promoting Spontaneous Second Harmonic Generation through Organogelation

An organogelator based on the Disperse Red nonlinear optical chromophore was synthesized according to a simple and efficient three-step procedure. The supramolecular gel organization leads to xerogels which display a spontaneous second harmonic generation (SHG) response without any need for preprocessing, and this SHG activity appears to be stable over several months. These findings, based on an intrinsic structural approach, are supported by favorable intermolecular supramolecular interactions, which promote a locally non-centrosymmetric NLO-active organization. This is in sharp contrast with most materials designed for SHG purposes, which generally require the use of expensive or heavy-to-handle external techniques for managing the dipoles' alignment.

Spontaneous symmetry breaking of Co(ii) metal–organic frameworks from achiral precursors via asymmetrical crystallization

Enantioenriched 3D pseudo-enantiomorphs integrating porosity, chirality and magnetism together with different colour and morphology were obtained through spontaneous symmetry breaking.

A homochiral magnet based on D3 symmetric [(NaO3)Co3] clusters: from spontaneous resolution to absolute chiral induction

A pair novel 3D chiral magnets have been synthesized using the achiral ligand imidazole-4-acrylate via spontaneous resolution, in which the D₃ symmetric chiral [(NaO₆)Co₃] clusters act as nodes. By using chiral induction agent, they are driven to controllable homochiral crystals.

A flexible zwitterion ligand based lanthanide metal–organic framework for luminescence sensing of metal ions and small molecules

A new 3D luminescence LnMOF was synthesized using a tripodal flexible zwitterion ligand which takes a chair-shaped configuration. The compound displays highly selective luminescence sensing of the Fe³⁺ ion and nitrobenzene.

Coligand-directed synthesis of five Co(ii)/Ni(ii) coordination polymers with a neutral tetradentate ligand: syntheses, crystal structures, and properties

The solvothermal reactions afforded five coordination polymers with different coligands, and the coligand-directed synthesis has a great effect on the final structures.

Seven novel coordination polymers constructed by rigid 4-(4-carboxyphenyl)-terpyridine ligands: synthesis, structural diversity, luminescence and magnetic properties

Seven coordination polymers, namely [Mn(4-cptpy)2]n (1), [Co(4-cptpy)2]n (2), [Mn3(4-cptpy)6(H2O)]n·2nH2O (3), [Co(4-cptpy)(HCOO)(H2O)]n·nDMF (4), [Zn2(4-Hcptpy)2Cl4]n·2nC2H5OH·nH2O (5), [Co4(3-cptpy)4(HCOO)4(H2O)2]n (6), and [Mn(3-cptpy)2]n (7) (4-Hcptpy = 4-(4-carboxyphenyl)-4,2':6',4''-terpyridine; 3-Hcptpy = 4-(4-carboxyphenyl)-3,2':6',3''-terpyridine), have been synthesized under hydro(solvo)thermal conditions and structurally characterized. A general solvothermal method is proposed for preparing carboxylate complexes in DMF solution without any basic additive. 1 and 2 possess isostructural 3D metal-organic frameworks containing nanosized cavities. 3 is a beautiful 2D coordination polymer assembled by flower-like Mn3(4-cptpy)6(H2O) subunits. 4 and 6 both display 2D polymeric networks constructed from 4/3-cptpy(-) ligands, in which the formate ligands originate from the hydrolysis of DMF. 5 is a 1D 2(1) helical chain polymer. 7 shows a 2D network with a (3.6) two-nodal kgd topology. 4/3-Hcptpy ligands display seven types of coordination modes. The zinc complex 5 emits strong violet luminescence. 1 and 2 are both thermally stable below 440 °C and exhibit antiferromagnetic interactions.