Toward Efficient Synthesis of Porous All-Carbon-Based Nanocomposites for Enantiospecific Separation

UiO-67-Typed Zr-MOFs Modified with Chiral Amine Alcohol Pendants for Adsorption Separation of Chiral Aromatic Alcohol Enantiomers

Robust UiO-67-typed Zr-HMOFs 1 and 2 (HMOFs = homochiral metal-organic frameworks) functionalized with isomeric chiral amine alcohol pendants, which have the same topology, but the relative positions between hydrogen-bonding sites and chiral carbons are different, were synthesized as adsorption platforms for the enantioseparation of 1-phenylethanol, 1-phenyl-2-propanol, and 2-phenyl-1-propanol. Both materials exhibited effective enantioseparation performance for the aforementioned alcohols. Particularly, 2 achieved an enantiomeric excess (ee) value of 96.4% for 1-phenylethanol, while 1 exhibited an exceptionally high ee value of 99.6% for 2-phenyl-1-propanol, ranking among the highest ee values reported for HMOFs. Based on the experimental results and host-guest structure analysis, it can be inferred that the higher the similarity of groups directly bonded to the chiral carbon in Zr-HMOFs and substrate, the better the performance of enantioseparation. Replacing the chiral ligand in material 1 with an achiral ligand with the same skeleton, four 1@x % (x % being the molar percentage of chiral ligand used during synthesis) materials were synthesized to explore the impact of the framework's pore size and chiral active site concentration on enantiomeric separation performance. The results showed that 1@50% had the highest adsorption capacity and ee value for 1-phenylethanol, which were 47.7 mg g-1 and 98.6%, respectively.

Preparation of amino acid chiral ionic liquid and visual chiral recognition of glutamine and phenylalanine enantiomers

In this paper, the amino acid chiral ionic liquid (AACIL) was prepared with L-phenylalanine and imidazole. It was characterized by CD, FT-IR, 1H NMR, and 13C NMR spectrum. The chiral recognition sensor was constructed with AACIL and Cu(II), which exhibited different chiral visual responses (solubility or color difference) to the enantiomers of glutamine (Gln) and phenylalanine (Phe). The effects of solvent, pH, time, temperature, metal ions, and other amino acids on visual chiral recognition were optimized. The minimum concentrations of Gln and Phe for visual chiral recognition were 0.20 mg/ml and 0.28 mg/ml, respectively. The mechanism of chiral recognition was investigated by FT-IR, TEM, SEM, TG, XPS, and CD. The location of the host-guest inclusion or molecular placement has been conformationally searched based on Gaussian 09 software.

Pillararene-based molecular-scale porous materials

This review discusses the design and syntheses of molecular-scale pillar[n]arene-based porous materials with promising applications and summarises the development of using pillar[n]arenes as the building blocks of porous materials. From the perspective of "role of participation" in the syntheses of molecular-scale pillar[n]arene-based porous materials, the content can be divided into pillar[n]arenes serving as supramolecular nanovalves on surfaces and as ligands for metal-organic frameworks and covalent organic polymers. By integrating pillararenes, which possess rigid pillar-like structures, electron-rich cavities and desirable host-guest properties, with porous polymers of large surface areas and abundant active sites, applications of the resulting materials in drug release platforms, molecular recognition, sensing, detection, gas adsorption, removal of water pollution, organic photovoltaic materials and heterogeneous catalysis can be realised simultaneously and efficiently. Finally, in the conclusions and perspectives part, we put forward the challenges and viewpoints of the current research on pillar[n]arene-based porous materials. We hope this article can provide a timely and valuable reference for researchers interested in synthetic macrocycles and porous materials.