Bio‐Templated Chiral Zeolitic Imidazolate Framework for Enantioselective Chemoresistive Sensing

Abstract

Chiral metal-organic frameworks (MOFs) have gained rising attention as ordered nanoporous materials for enantiomer separations, chiral catalysis, and sensing. Among those, chiral MOFs are generally obtained through complex synthetic routes by using a limited choice of reactive chiral organic precursors as the primary linkers or auxiliary ligands. Here, we report a template-controlled synthesis of chiral MOFs from achiral precursors grown on chiral nematic cellulosederived nanostructured bio-templates. We demonstrate that chiral MOFs, specifically, zeolitic imidazolate framework (ZIF), unc-[Zn(2-MeIm) 2 , 2-MeIm = 2-methylimidazole], can be grown from regular precursors within nanoporous organized chiral nematic nanocelluloses via directed assembly on twisted bundles of cellulose nanocrystals. The template-grown chiral ZIF possesses tetragonal crystal structure with chiral space group of P4 1 , which is different from traditional cubic crystal structure of I-43 m for freely grown conventional ZIF-8. The uniaxially compressed dimensions of the unit cell of templated ZIF and crystalline dimensions are signatures of this structure. We observe that the templated chiral ZIF can facilitate the enantiotropic sensing. It shows enantioselective recognition and chiral sensing abilities with a low limit of detection of 39 μM and the corresponding limit of chiral detection of 300 μM for representative chiral amino acid, D-and Lalanine.

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“…Ligands are currently the most dominant source of chirality in nanomaterials due to their diversity and specificity, making them the most promising for potential applications . It has long been accepted that only l -amino acids are found in nature and are simultaneously active, whereas d -isomers are synthesized in laboratories and have even a deleterious impact on organisms.…”

Enhancing Electrochemical Signal for Efficient Chiral Recognition by Encapsulating C60 Fullerene into Chiral Lanthanum-Based MOFs

“…13 In comparison with conventional methods, electrochemical approaches have attracted widespread attention for their convenience of installation, inexpensive, faster response, sensitive recognition, and friendliness to the environment. 14,15 Currently, existing studies have designed chiral sensing platforms based on a variety of materials such as inorganic nanoparticles, 16 organic compounds, 17 polysaccharides, 18 proteins and metal−organic frameworks to distinguish Trp enantiomers, 19 among which chiral metal−organic frameworks (CMOFs) are widely used for the fabrication of chiral materials owing to their regular microporous structures, shapes, surface functionalities, and even morphologies, 20,21 which can be highly designed by rational combinations of the components. 22 CMOFs can be classified into two species, one requires a chiral bridging ligand to impart chirality and that the other does not necessitate a chiral bridging ligand but displays chirality in its framework construction.…”

“…In recent years, a variety of analytical techniques have been proposed to distinguish and detect Trp isomers, including chemiluminescence, high-performance liquid chromatography (HPLC), and capillary electrophoresis, , with significant sensitivity and accuracy; however, the traditional methods still have limitations of high instrumental expenses, complicated sample manipulation, time-consuming experimental procedures, and the necessity of operator training . In comparison with conventional methods, electrochemical approaches have attracted widespread attention for their convenience of installation, inexpensive, faster response, sensitive recognition, and friendliness to the environment. , Currently, existing studies have designed chiral sensing platforms based on a variety of materials such as inorganic nanoparticles, organic compounds, polysaccharides, proteins and metal–organic frameworks to distinguish Trp enantiomers, among which chiral metal–organic frameworks (CMOFs) are widely used for the fabrication of chiral materials owing to their regular microporous structures, shapes, surface functionalities, and even morphologies, , which can be highly designed by rational combinations of the components . CMOFs can be classified into two species, one requires a chiral bridging ligand to impart chirality and that the other does not necessitate a chiral bridging ligand but displays chirality in its framework construction .…”