English

• 1. Introduction

  Early in 1815, a French scientist Biot first clearly discovered the phenomenon of optical rotation when some aqueous solution of organic compounds can make the direction of polarization rotate. Several decades later, another chemist Pasteur successfully separated two kinds of crystals of racemic ammonium tartrate sodium salt from each other under the microscope, and concluded that the optional rotation of the substance was related to the internal chemical structure, and thereafter revealed the structural origin of optical activity in 1848 [1,2]. With further study of enantiomers, it is indicated that the spatial arrangement of atoms inside the left-hand and right-hand enantiomers is a non-coincident physical and mirror relationship and consistent with the left and right hands. Nowadays, chirality has been recognized as a special feature of various levels of matter, which plays an essential role in the generation and evolution of life processes or even the whole universe [3]. For example, L-amino acids are favoring to construct diverse proteins and enzymes, while D-sugars are elementary building blocks of nucleic acids. In particular, the chirality has a pronounced impact in biological systems owning to the different host-guest interactions [4]. The specific chiral recognition and matching behaviors between different isomers and living macroenvironment may lead to distinct pharmacological effects in living organisms. A typical example is the “thalidomide tragedy” in 1960s [5], when thalidomide was widely used to treat vomiting symptoms in pregnant women in European. Subsequent studies found that only the R-isomer of the thalidomide was a sedative effect, while its S-isomer was terribly teratogenic. Afterward, plenty of examples about adverse effects caused by enantiomers were happened, such as β-blocker R/S-propranolol [6], s-perindopril [7], and d/l-carnitine [8].

  As a great demanding for pure chiral compounds in pharmaceutical industry, a great number of crucial research efforts has been devoted to develop effective and practical methods [9]. However, the two isomers almost have the same chemical properties, except for optical rotation, making it challenging to acquire. Generally, there are three classical methods to obtain pure isomer: (1) Asymmetric synthesis; (2) chiral source synthesis; and (3) racemic separation. Meanwhile, the process of splitting racemates into optically pure enantiomers is called racemic separation. The racemic separation has demonstrated a number of advantages [10,11]. Primarily, the racemic separation can provide a highly quantitative yields of each enantiomer. Then, racemic separation was regarded as an eco-friendly method, featuring green economy [12,13]. However, the process of asymmetric and chiral source synthesis is difficult to control and industrial production, and more importantly, the reaction progress was accompanied with by-product and toxic substances.

  Currently, chiral chromatographic technologies have become one of the most efficient, useful and versatile separation tools in the field of racemic separation. Schurig et al. [14] concluded that there are three principal interactions between the chiral molecules and chiral stationary phases (CSPs) in chromatographic tools, namely, coordination, inclusion and hydrogen bonding, resulting in stereospecific formation of distinguishable transient diastereomeric complexes in terms of kinetical and energetical difference. Advances in the development of chiral chromatographic separations lies in the design and exploration of efficient CSPs. Amount of crucial research efforts have been dedicated to develop of numerous functional materials used as chromatographic CSPs for racemic separation, including gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrochromatography (CEC). At present, the main chiral functional materials are concluded inorganic nanomaterials [15], ionic liquids (ILs) [16], polymers materials [17], deep-eutectic solvents (DES) [18], covalent organic frameworks (COFs) [19], and metal-organic frameworks (MOFs) [20].

  Nowadays, MOFs are recognized as a kind of special nano-porous crystal hybrid materials, constructing by self-assembly of metal ions or metal clusters and organic ligands [21,22]. In comparison with conventional materials such as graphene oxide, zeolites, polymers, and nanomaterials, MOFs not only have inorganic and organic properties, but also have a greater porosity, higher surface area, and more flexible structure, making them an appropriate candidate in various areas, including chromatographic separation [23,24], catalysis [25,26], gas storage [27], chemical sensing [28], membranes [29], drug delivery [30], proton conduction [31], and electron conduction [32]. Chiral MOFs (CMOFs) are a subclass of functional MOFs with chiral building blocks [33-35], not only with large specific surface and porous structure, but also with adjustable chiral microenvironment. The chirality is intrinsic property of the natural biomolecules that involve multiple levels of chirality, terming multi-chirality [36,37]. On account of the high modularity, the interior surfaces of CMOFs can be tailored accurately, providing suitable host-guest chiral recognition interactions. The emerging CMOFs with versatile functionality and fascinating properties promote tremendous potential for effective chiral chromatographic technologies [38,39].

  Herein, this main contribution of the present review is included our perspectives on CMOFs-based chiral chromatographic technologies for racemic separation, facilitating an in-depth understanding of CMOFs materials not only for the design and fabrication but also for their corresponding applications in producing pure enantiomers. First of all, the mechanisms and target-specific synthesis strategies of various CMOFs are elucidated systematically. Secondly, we sequentially summarize and classify the application of CMOFs regarding as the chromatographic CSPs in HPLC, CEC, and GC for racemic separation. Last but not least, some challenges and opportunities about the application of CMOFs are also put forward concisely, hoping to contribute to the development of CMOFs for chiral chromatographic enantioseparation.

  2. Mechanism of racemic separation in CMOFs

  Understanding the racemic separation mechanism of CMOFs plays a crucial role in designing, synthesizing and improving of enantioselectivity of CMOFs for chiral chromatographic technologies. As we all know, racemic separation is attributed to their different adsorption ability which is heavily depended on the associated interactions between adsorbates and adsorbents. However, there is currently no particular, general mechanism for the racemic separation of CMOFs due to the differences of enantiomers only in the spatial arrangement of their atoms. Herein, we propose that chiral microenvironment is mainly concentrated on the channels and pores of CMOFs, making it is feasible for racemic separation [40]. On this basis, the enantioselective mechanism is attributed to the precise and stereoselective interaction, forming labile diastereoisomeric complexes by chiral microenvironment. Therefore, the difference of the steric effect and enantioselective ability between the chiral microenvironment and analytes is the key to the racemic separation [41].

  First of all, the steric effect between the chiral microenvironment of CMOFs and the chiral compounds are complex. The racemic separation usually occurs on the inner surfaces of chiral channels and pockets duo to the CMOFs have a diverse porosity and large surface [42]. Therefore, the steric effect is mainly manifested in shape/size-matching. The racemic separation is that if an isomer better matches the chiral microenvironment of CMOFs, better entering the pores of chiral pockets or channels. It may be helpful to understand how the steric effect of chiral microenvironment work according to different enantiomeric selectivity. Then, the racemic separation also depends on distinguishable enantioselective ability [43,44], and this discrepancy of enantioselectivity may contribute to the different absorption between host and guest. The strength of enantioselective ability can be reflected in the different complexation and binding energy. For racemic separation, the various chiral microenvironment of CMOFs work cooperatively to induce enantioselective absorbing and binding of guests. While there is a slightly differentiated absorption between host and guest, the racemic separation was performed through the formation of enantiomer complexes or diastereomers [45]. In addition, the hydrogen bonding, van der Waals force, bond interaction, electrostatic force, and dipole interaction also play a significant role in racemic separation [46].

  3. The principle of design and syntheses CMOFs

  The enantioselective adsorption of CMOFs for racemic separation is attributed to the presence of chiral recognition sites in the microenvironment. Therefore, the precise and convenient construction of chiral recognition sites into interior surfaces of CMOFs is a critical step. In principle, the fabrication of CMOFs is mainly focused on when, where, and how to assemble the chirality inside framework of achiral MOFs. From achiral MOFs transform to CMOFs, it must crystallize more than 65 chiral space groups via either the chiral arrangement or incorporation of chirality in resultant framework [47]. Typically, the approaches of introducing chirality inside achiral MOFs can be divided into three kinds: (1) Direct synthesis where enantiopure chiral linkers were derived from these original frameworks; (2) Post-synthesis means to first synthesize achiral MOFs and then assemble appropriate chiral linkers to implant chirality into entire MOF framework; (3) Spontaneous resolution and chiral induction method where achiral components arrange in a chiral form to generate enantiomerically pure framework, as shown Fig. S1 (Supporting Information). In this section, we will informatively elucidate of the classical approaches with the most representative works over the past two decades, hoping that the review will act as a springboard to design diverse CMOFs for chromatographic enantioseparation.

  3.1 Direct synthesis of CMOFs

  The direct synthesis is preferred and classical choice for fabricating CMOFs because the chirality conservation is well mature, becoming the most convenient, encouraging, and effective applied method. The advantage of direct synthesis is that the absolute bulk chiral microenvironment of the resultant framework can be easily established during the self-assembly process. Generally, there are two methods to directly introduce chirality into the resultant framework: (a) Merely using chiral linkers to connect inorganic building units, known as single-ligand strategy; (b) Using chiral and achiral linkers to bridge metal centers, namely mixed-ligand strategy. Therefore, the desirable chiral ligands can be introduced in framework according to different requirements [48,49]. Until to now, a lot of easily and readily available chiral linkers, such as amino acids, cyclodextrins, proteins, hydroxy and camphoric acid, enzyme, and alkaloids have dominated the preparation of CMOFs [50-52]. These functional groups can bridge to metal centers through various coordination modes. The introduction of chirality not only facilitate their direct construction of chiral microenvironment but also provide a valuable platform for further modification through simple conservation and conversion.

  In 2000, Kim’s group [53] first reported the construction of a pair of 2D chiral framework which was synthesized by oxo-bridged trinuclear zinc clusters and chiral additive D-tartaric acid as secondary building blocks. In the crystal structure, three zinc ions are held together with six carboxylate groups of the deprotonated chiral ligands and a bridging oxo oxygen, to form a trinuclear unit. The synthesis strategy, which uses enantiopure metal-organic clusters as secondary building blocks, provide access to a wide range of porous organic materials suitable for separation and catalysis.

  In 2004, Jacobson et al. [54] also reported the inchoate example of directly using inherent chiral linker to assemble parent MOF, a chiral 1D helical chain hybrid compound based on infinite helical chains of nickel octahedra was successfully synthesized through Ni-O-Ni bonding. Soon afterward, in 2006, the same group also synthesized a 3D CMOF based on helical chains with extended Ni-O-Ni bonding using pure enantiopure aspartic acid, giving rise to various chiral 3D framework networks [55]. Currently, in 2021, Cui’s group [56] reported the design and synthesis of five chiral additives with different functionalities, and then integrated into Zr-MOFs metal clusters framework to assemble a series of highly efficient CMOFs.

  Soon afterward, the chiral microenvironment of CMOFs assembled from a pure enantiopure ligand may be too dense to guarantee a suitable space, limiting the chiral coordination sites to access the guest. Herein, the mixed-ligand strategy has been widely studied and exploited for fabrication of multi-dimensional framework with diversified structures and functionalities. In 2011, the Sahoo’s group [57] elucidated a simple aldimine reduction reaction to assemble 3-methyl-2-(pyridin-4-ylmethylamino)-butanoic acid onto the backbones of valine and leucine, respectively. The assembled homochiral Zn-CMOFs with zeolitic unh-topology, using amino acid-derived links and Zn(CH₃COO)₂·2H₂O, were attracted and proved to be useful applications, as shown in Fig. 1a. In 2019, the Galan-Mascaros’s group [58] adapted a hydrazine-mediated condensation method with natural L-histidine and copper salt, a triazole group was derived and served as chiral sites for the assembly of a porous crystalline framework, showing excellent performance toward racemic separation (Fig. 1b). In 2014, Lin et al. [59] reported a robust and porous Zr-MOF based on a BINAP-derived dicarboxylate linker (BINAP-MOF) which was synthesized with Ru and Rh complexes. The BINAP-MOF afforded highly enantioselective catalysts (Fig. 1c).

  Figure 1

  

  Figure 1.  (a) Crystal structure of 3D Zn-CMOFs with unh-topology. Reproduced with permission [57]. Copyright 2011, American Chemical Society. (b) Crystal structure of Cu(H₂O)₂(S-TA)₂]·6H₂O. Reproduced with permission [58]. Copyright 2019, American Chemical Society. (c) Crystal structure of BINAP-MOF. Reproduced with permission [59]. Copyright 2014, American Chemical Society.

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  3.2 Post synthesis of CMOFs

  The great success in achieving desirable CMOFs by direct synthesis method is that the chiral linkers can be assembled in achiral MOFs uniformly. However, the direct-synthesis still has remained inadequate and challenging because of lacking functional chiral linkers and frequently incompatible with chirality. To alleviate above restrictions, another alternative strategy for synthesis of CMOFs called post-synthesis methods was emerged. The post-synthesis method is first to prepare achiral MOFs and then assemble chiral functional linkers into the framework of parent MOFs through chemical modification. The advantage of the post-synthesis is that accessible chiral microenvironment can be formed through introduction of desirable chiral functional linker without destroying the structural uniformity and original topology.

  Post-synthesis modification has become reliable method for the construction of CMOFs. For assembling the microenvironment of achiral MOFs, active groups such as amino, halogen, or methyl are usually introduced into organic ligands to enrich them chiral recognition sites. As one of the pioneering groups in post-synthesis, Cohen’s group [60] constructed chiral IRMOF-3 containing amino groups using chiral additive 2-amino-1,4-benzenedicarboxylic acid (NH₂-BDC), indicating that post-synthesis is a powerful and useful method to fabricate diverse structures (Fig. 2a). Soon afterward, He et al. [61] also reported the construction and investigation of chiral and photoluminescent MOF based on parent MOF and achiral methoxy-functionalized benzimidazolate (Bim) linkers. Notably, the resultant MeOBim-Zn exhibits photo-luminescence upon photoexcitation and specific enantioselective applications (Fig. 2b). Telfer et al. [62] reported a general strategy for incorporating chiral proline (Pro) into parent MOFs by a simple post-synthetic heating step. The method is exemplified using a thermolabile tert-butoxycarbonyl (Boc) protecting group for a proline moiety, endowing the resultant cubic IRMOF with high catalytic activity (IRMOF-Pro-Boc), as shown in Fig. 2c. Liu et al. [63] develop a novel strategy to synthesize CMOFs via a superficial chiral etching reaction, in which pre-synthesized parent MOF reacting with pure D-camphoric acid ligand without changing the porosity and pore structure, producing a core-shell hybrid composition (Fig. 2d).

  Figure 2

  

  Figure 2.  (a) Crystal structure of IRMOF-3. Reproduced with permission [60]. Copyright 2009, American Chemical Society. (b) Crystal structure of MeOBim-Zn. Reproduced with permission [61]. Copyright 2021, Elsevier. (c) Crystal structure of IRMOF-Pro-Boc. Reproduced with permission [62]. Copyright 2011, American Chemical Society. (d) Crystal structure of Cu₃(Btc)₂]@[Cu₂(D-Cam)₂. Reproduced with permission [63]. Copyright 2017, American Chemical Society.

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  Shi et al. [64] also demonstrated that the incorporation of pure chiral additive into the pores via post-synthetic cation exchange. An anionic Zn-MOF was applied as a platform to assemble chiral N-benzylquininium chloride linker into cavities. Subsequently, the incorporated cations were partially replaced by Tb³⁺ to generate a bifunctional chiral center in the channels (Fig. 3a). Cui et al. [65] employed a post-synthetic ligand exchange strategy to incorporate pure chiral M(salen) linkers into Zr-based UiO-68 frameworks, producing a series of CMOFs, which demonstrated excellent catalytic performance for various asymmetric reactions (Fig. 3b). Very recently, Cao et al. reported post-synthetic exchange of MOF-808 by substituting of coordinated modulators on the secondary building units of parent MOF with diverse chiral additives (His, Tar, and Glu), demonstrating a simple and low-cost post-synthetic modification method to introduce multi-chirality into MOFs [66].

  Figure 3

  

  Figure 3.  (a) Crystal structure of Zn-MOF. Reproduced with permission [64]. Copyright 2019, Nature. (b) Crystal structure of Zr-based UiO-68. Reproduced with permission [65]. Copyright 2018, American Chemical Society.

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  3.3 Spontaneous resolution and chiral induction method

  Currently, the method without any chiral linkers has become popular for synthesis of CMOFs. Generally, the connection of metal ions with achiral linkers would most likely lead to the formation of centrosymmetric assemblies. Therefore, the unique spatial arrangement of each achiral building block results in asymmetric crystallization, affording overall structural chirality. Spontaneous resolution method is to construct CMOFs by coordination of metal salts and achiral ligands. Chiral induction method is to introduce additional chiral auxiliary spectator, directly inducing specific chiral microenvironment into the frameworks. In this part, we will elucidate several significant milestones in terms of spontaneous resolution and chiral induction method.

  For spontaneous resolution, the construction process is in the lack of any chiral additive. In the early 2003 and 2004, Yan et al. [67,68] reported that an achiral diazine ligand, 2-pyridylmethylketazine, which can be locked in a chiral conformation upon coordination via single azido bridges, was incorporated into the manganese(Ⅱ)-azido system by partial weak ferromagnetism and spontaneous resolution. Soon afterward, Zhang’s group [69] reported that an axially CMOF which was generated by symmetric breaking from metal ions and achiral pyridyl dicarboxylate ligand 5-(pyridine-3-yl)isophthalic acid, establishing chiral transmission from molecular axially chiral conformations into framework. Boom et al. [70] independently reported three CMOFs constructed from three different achiral tetrahedral pyridine additives and copper dichloride, respectively, indicating that the achiral tetrahedral additives have become mainstream to form chiral microenvironment inside parent MOFs via spontaneous resolution. Soon afterward, Eddaoudi et al. [71] reported a novel homochiral zeolitic MOF. The zeolite-like framework process DNA-like polymers with double-helicity. Evidently, the highly stability and chiral channels of multi-dimensional framework offered enantioselective separation of chiral molecules, as well as small gas molecules (Fig. 4a).

  Figure 4

  

  Figure 4.  (a) Crystal structure of [(Cu₄I₄)(dabco)₂]·[Cu₂(bbimb)]·3DMF. Reproduced with permission [71]. Copyright 2016, American Chemical Society. (b) Crystal structure of FJI-H16 and FJI-H27. Reproduced with permission [72]. Copyright 2021, Wiley. (c) Crystal structure of [Zn(SO₄)(L)(H₂O)₂]_n. Reproduced with permission [73]. Copyright 2013, American Chemical Society.

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  Chiral induction is another alternative method to obtain bulk CMOFs. In comparison with direct or post synthesis, the process may be partially addressed by the assembly or crystallization but are not all of it. Hong et al. [72] first prepared 2D coordination polymer system by assembling achiral H₃BTB ligands and Zn²⁺, Cd²⁺ clusters, and finally constructed a 3D CMOF (FJI-H27(M) or (P)) by introduction of achiral pyridine into above assembly system (Fig. 4b). The overall driven force was generated by a pyridine participated dynamic-control assembly process. Suresh et al. [73] reported two enantiomeric pairs of isostructural 2D MOFs comprising of achiral building blocks by the spatial orientation of the ligand moiety coordinated to the metal (Fig. 4c).

  Expanding this strategy, Wu et al. [74] utilized enantiopure camphor sulfonic acid as a chiral induction additive, 3D homochiral CMOF were fabricated from achiral 2D layers and manganese tetroxide ion pillars. Through the synergistic effect of pillaring strategy and chiral induction, the new method can be used to prepare homochiral 3D coordination polymers from achiral additives (Fig. 5a). Zhao et al. [75] used chiral D-camphoric acid, a low-cost and versatile chiral building block, as the cross-linking ligand to fabricate a series of CMOF through chirality induction (Fig. 5b). Currently, Wang et al. [76] synthesized another 2D heterometallic mixed Zn(Ⅱ) and Cd(Ⅱ) organic framework by solvothermal reaction based on chiral Zn-Salen ligands in 2022.

  Figure 5

  

  Figure 5.  (a) Crystal structure of 3D MOF. Reproduced with permission [74]. Copyright 2014, Royal Society of Chemistry. (b) Crystal structure of CPM-311 and CPM-312. Reproduced with permission [75]. Copyright 2018, Wiley.

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  To conclude, we systematically analyzed and discussed the protocols of construction homochiral MOFs that have been reported to date. The synthetic strategies have been divided into direct-synthesis, post-synthesis, and spontaneous resolution and chiral induction. Obviously, each method has its advantages and disadvantages, and the chosen one should be decided according to the desirable requirements and specific conditions. The listed CMOFs with structural chirality by the above methods were shown in Table S1 (Supporting information).

  4. Applications of CMOF as the CSP in chromatographic enantioseparation

  As we all known, the CMOFs are enriched with multifunctional chirality, distinguishing themselves from conventional porous chiral materials. The highly modular toolkit provides a well-off opportunity for the introduction of multiple-chirality, making them as a suitable candidate for chromatographic enantioseparation. In this part, we try to comprehensively address racemic separation in terms of CMOFs as ideal chromatographic CSP candidates in GC, HPLC, and CEC.

  4.1 CMOF-CSPs for GC racemic separation

  GC technology is a powerful and effective separation method due to its simple, rapid, high-selective and easy-accessible. It has been widely used for separation of analytes that are easily vaporize without decomposition. In recent years, GC based on CMOFs has become the most attractive method for racemic separation. So far, plenty of CMOFs have shown great potential for GC enantioselective separation. In this part, we will showcase the CMOF-CSPs for GC racemic separation in chronological order.

  In 2011, Yuan’s group first successfully fabricated a CMOF-based open tubular column for high-efficiency GC racemic separation [77]. First, the 3D MOF was synthesized by the addition of cupric acetate and H₂sala. Then, the fused-silica open tubular column was prepared by a dynamic coating method using an ethanol suspension of the CMOF and [Cu(sala)]_n. The developed GC system performs excellent enantioselective ability toward a wide range of organic compounds such as alkanes, alcohols, and isomers (Fig. S2 in Supporting information). This work provides a roadmap for developing CMOF-CSPs-based chromatographic system in racemic separation.

  From 2013 to 2016, especially in 2013, Yuan et al. also reported a series of MOFs with a left-handed helical channel assembled from pure chiral camphoric acid. The above CMOFs-coated open tubular columns were prepared and installed in GC system for high-efficiency racemic separation of diverse organic compounds [78-80]. Soon afterward, in 2014, Yuan’s group [81,82] also synthesized two kinds of CMOFs with macropore and right-handed helical structure and used as the CSPs in GC system for racemic separation. In 2015, Yuan’s group [83] made another homochiral 3D framework as the CSP for high-efficiency toward racemates in GC system. Subsequently, in 2016, Zhang et al. [84] successfully prepared enantiopure substrate mounted CMOF by introducing 3,4-dihydroxy-L-phenylalanine as a chiral additive (Fig. 6a). The CMOF growth on functionalized substrate in capillary column by using layer-by-layer liquid phase epitaxy method (Fig. 6b). The obtained chiral GC system showed improved enantioselective ability for methyl lactate (Fig. 6c).

  Figure 6

  

  Figure 6.  The Cu₂(D-Cam)₂dabco@Poly(L-DOPA) for GC separation of racemates. (a) The fabrication of CMOF, (b) the SEM images of inner surface of column, (c) the chromatograms of enantioseparation. Reproduced with permission [84]. Copyright 2016, Royal Society of Chemistry.

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  In 2017, Yuan et al. [85] reported a novel CMOF of Co-L-GG (L-GG, dipeptide H-Gly-L-Glu) as the chromatographic CSP for enantioselective separation. The Co-L-GG modified capillary column demonstrated higher efficiency and enantioselectivity for various racemates. The recognition mechanisms are attributed to the steric fit and diverse molecular interactions, such as dispersion, dipole-dipole, and hydrogen bond forces. In the same year, by virtue of the high enantioselectivity and excellent chiral chromatographic performance of β-cyclodextrins (β-CDs) and MOFs, Yuan et al. first investigated the chiral synergistic effect of β-CDs and MOFs as mixed CSPs for the GC racemic separation [86-88]. The results indicated that the use of synergistic CSPs could improve efficiency of GC enantioselective separation. Meanwhile, Yan and their co-workers [89] also made a lot of contributions in developing effective CMOFs in GC separations. He reported a unique porous crystalline metalorganic material (CMOM-3S) in which exhibits inherent chirality, serves as a general-purpose CSP for GC racemic separation. The properties of CMOM-3S are enabled by nanosized channels connected to adaptable chiral recognition sites that mimic enzyme-binding sites (Figs. 7a and b). The mechanism of chiral binding sites was discussed in Fig. 7c. The outstanding performance of separation for racemates was shown in Fig. 7d. In addition, Zeng et al. [90] reported the use of a multi-functional ligands rod-spacer as coating material for GC separation of biochemical compounds. The multi-functional likers with stable thermodynamics and effective interaction sites are attributed to the high efficiency in GC racemic separation.

  Figure 7

  

  Figure 7.  The CMOF-3S for GC separation of racemates. (a, b) The fabrication of CMOF, (c) the mechanism of chiral binding sites, (d) the chromatograms of enantioseparation. Reproduced with permission [89]. Copyright 2017, Cell.

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  Recently, in 2018, Yan and colleagues [91] reported a post-synthesis approach for the facile preparation of a series of CMOFs as the CSPs for GC racemic separation. Five CMOFs with different chiral microenvironment were synthesized and assembled into identical parent MIL-101-NH₂. The CMOF-coated OT-CEC system indicated superior enantioselective efficiency for a wide range of racemates compared with the commercial columns. In terms of the enantioselective ability, the difference of the five CMOFs can be explained by the different levels of shape/size-matching degree between the host and guest. This above strategy avoids the blinded synthesis of CMOF and facilitates the development of CSPs in GC system.

  The listed of overall CMOFs used as CSPs for GC enantioselective separation were included in Table 1. To conclude, the adoption of CMOFs as the CSPs in GC system has been acknowledged with relatively high efficiency and selectivity for separating plenty of racemates.

  Table 1

  

  Table 1.  Summary of the different CMOFs for GC racemic separation.

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  4.2 CMOF-CSPs for HPLC racemic separation

  HPLC is widely regarded as another fastest and most effective chromatographic technology due to its available simplicity and operation. The primary difference is that HPLC uses liquid mobile phases, whereas the GC uses gaseous mobile phase. In other words, HPLC can separate and analyze any soluble substances while GC can only operate volatile compounds, expanding its score of applications than GC and making it the perfect candidate for racemic separation. In this part, we will summarize the CMOF-CSPs for HPLC enantioselective separation in chronological order.

  In 2007, Fedin and co-workers were first successfully developed CMOF as the LC CSP for enantioselective separation [92]. According the work, they adopted 3D porous Zn-organic framework as the chromatographic CSP for the separation of racemic mixtures. The developed HPLC system possessed the intrinsic chirality due to the chiral L-lactic acid. The racemate of sulfoxides was chosen as target substrate to check the performance of the packed column. The (R)-isomer comes out first during the elution, followed by a peak of the (S)-isomer. Despite some peak overlap, the major part of the sulfoxides could be collected separately as optically pure (R)- or (S)-enantiomers. This pioneering work provide the feasibility of CMOF-CSPs-based HPLC racemic separation. A few years later, Kaskel et al. [93] reported highly uniform CMOFs which were decorated with chiral auxiliary by developing a modular approach. The fabricated HPLC system hinted enantioselective ability for 1-phenylethanol racemate. Then, Tanaka et al. [94] also reported that HPLC enantiomeric separation using a new homochiral MOF-silica composite as the chromatographic CSP. The performance of the column packed with (R)-MOF-silica composite was evaluated for separating plenty of sulfoxides, showing highly efficient in this system. The outcomes may bring a bright future for CMOF materials in the HPLC enantioselective separation widely.

  In 2013 and 2014, many groups made a lot of contributions to this field. Yuan and co-workers [95] reported a 3D chiral nano-porous MOF as a novel CSP in capillary column. The developed HPLC system gave high efficiency for the racemic separation of flavanone, 3-benzyloxy-1,2-propanediol, and benzoin. Cui et al. [96] reported two isostructural CMOFs decorated with chiral dihydroxy auxiliares from enantiopure tetra-carboxylate-bridging ligands and a manganese carboxylate chain. The packed HPLC column was evaluated by using 1-phenylethylamine analyte, achieving high enantioselective factor and chromatographic resolution. Yuan et al. [97,98] reported two typical homochiral helical MOFs which consisted of homochiral layers pillared by bipyridine ligands, leading to the formation of two different 3D six-connected self-penetrating architectures. As result, plenty of racemates were well separated on the chiral helical CMOFs based HPLC system. In conclusion, the excellent chiral recognition ability is attributed to the chiral microenvironment of above CMOFs. Tang et al. [99] prepared a noninterpenetrated 3D homochiral MOF with their minimum channel size and kinetic diameter, which was further used as a CSP for HPLC system to racemic separation of phenyl-1-propanol, ibuprofen, phenylethylamine, and benzoin, showing excellent performances (Fig. 8a). In this work, the enantiopure pyridyl-functionalized salen N-(4-pyridylmethyl)-L-leucine-HBr was used to assemble into parent MOF (Fig. 8b). A good enantioselective factor and high resolution was achieved in the developed chromatographic system (Fig. 8c). The 3D CMOF can be regarded as a novel molecular sieve-like material with a chiral microenvironment based on the shape/size-matching of the chiral channels and the target molecules. Turner et al. [100] reported two novel enantiomerically pure 2D and 3D interpenetrated materials. The interpenetrated CMOFs, containing solvent-filled pores and a close-packed analogue, have been hinted to act as positive CSP for HPLC enantioselective separation in micro-column.

  Figure 8

  

  Figure 8.  HPLC racemic separation of four kinds of enantiomers. (a) The chiral binding sites, (b) the SEM images of CMOF, (c) the performance of separation racemates. Reproduced with permission [99]. Copyright 2014, American Chemical Society.

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  In 2015 and 2016, Yuan et al. [101] reported a homochiral MOF based on six-connected paddlewheel building blocks which were bridged by bidentate carboxylate groups from D-camphoric acid. The material decorated with a non-interpenetrating primitive cubic net has been fantastic used as chromatographic CSP in HPLC system, affording the successful separation of positional isomers and chiral compounds. More than that, Liu et al. [102] also presented a planar Mn₄O-based homochiral MOF that could be used as a powerful and practical CSP for the racemic separation in HPLC. The column packed with activated chiral material for enantioselective separation of ibuprofen and 1-phenyl-1,2-ethanediol, showing excellent higher resolution and longer service life. Tanaka and co-workers [103] presented two kinds of pillared homochiral CMOFs. The preeminent chiral recognition ability mostly depends on the interaction of the analytes with the homochiral cylindrical channels. Soon afterwards, Yuan et al. [104] continued to synthesize a homochiral MOF [Cu(S-mal)(bpy)]_n with 3D chiral networks by the reaction of ligands (s-malic acid and 4,4′-bipyridine) with copper acetate via a solvothermal method. A packed chiral column for HPLC system was fabricated by functional materials, exhibiting good resolving ability towards plenty of racemates.

  From 2017 to 2019, Yuan et al. [105] reported that six homochiral MOFs constructed from Zn(Ⅱ) or Co(Ⅱ) ions and various enantiopure chiral additives were studied as the CSPs for HPLC chromatographic system, achieving high enantioseparation efficiency due to the multifunctional groups on the surfaces. Yan et al. [106] developed γ-CD@MOF for efficient and useful separation of chiral aromatic alcohols. In this work, more than twelve chiral aromatic alcohols were well separated on γ-CD@MOF packed HPLC column with good precision and selectivity. The hydrophobic cavity and the hydrophilic rim of the γ-CD@MOF are the ideal chiral enantioselective sites for chiral aromatic alcohols. In 2018, Yuan and co-workers [107] reported that a homochiral MOF [Cu(S-mal)(bpe)]_n was synthesized and packed column for HPLC system separation of racemates. A variety of different types of racemic compounds can be separated on the homochiral composite based HPLC system with high enantioselectivity. In 2019, Galan-Mascaros and coworkers [58] reported an advanced CMOF in which was derived from natural L-histidine by a novel designed synthesis method. The TAMOF-1 composite based HPLC chromatographic separation method has shown to be able to separate a variety of racemic mixtures in a wide range of different polar solvents, outperforming several commercial chiral columns for HPLC separations.

  In 2020, the development of CMOFs for HPLC system enantioselective separation are booming fleetingly. Yuan et al. [108] prepared a homochiral D-His-ZIF-8@SiO₂ composite by growing of D-His-ZIF-8 on the carboxylic-functionalized SiO₂ microspheres via a simple one-pot synthesis approach. The core-shell microspheres with narrow size distribution and uniform particles were applied as HPLC chromatographic CSP for enantioseparation. The developed HPLC system indicated excellent chiral recognition ability towards various racemic compounds with good reproducibility and stability. Yu et al. [109] reported an efficient and practical one-pot method for the immobilization of [Cu₂(D-Cam)₂Dabco]·(Cu₂C₂D) onto micro-spheric silica particles. Based on hydrophobic and hydrogen-bonding, successful and excellent racemic separation could be achieved among different types of chiral compounds such as carboxylic acid, ketones and phenols.

  In 2021, many groups have devoted great efforts to this field, especially Yuan’s group. Yuan et al. [110] synthesized a homochiral MOF composite by the reaction of S-malic acid and 4,4′-bipyridine with nickel acetate and utilized as a new CSP for HPLC system, exhibiting good chiral recognition ability toward plenty of racemic compounds. Yuan and colleagues also [111-114] adopted an in-situ growth method to prepare diverse monodisperse CMOFs as CSPs for HPLC racemic separation. The different fabricated CSPs column exhibited excellent enantioselective ability toward various racemates. Cui et al. [115] also designed and synthesized three kinds of chiral additives and constructed corresponding porous Zr(Ⅳ)@CMOFs. The different composites packed HPLC columns provide high selectivity and persistence for the separation of a wide variety of racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation (Fig. 9). Fig. 9a was the structure and chiral binding sites of CMOF. And more importantly, Fig. 9b showed the excellent efficiency for chiral separation.

  Figure 9

  

  Figure 9.  HPLC racemic separation of enantiomers with robust Zr(Ⅳ)-based CMOFs. (a) The mechanism of CMOF, (b) the performance of enantioseparation. Reproduced with permission [115]. Copyright 2021, American Chemical Society.

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  Currently, Yuan et al. [116] prepared an achiral@CMOF core-shell composite by a superficial chiral etching method. The core-shell composite was explored as a novel CSP for HPLC racemic separation, exhibiting good chiral resolving ability toward plenty of different kinds of racemates. Ouyang et al. [117] proposed a simple, green post-synthetic modification strategy for the fabrication of L-tyrosine functionalized Co-MOF-74, namely Co-MOF-74-L-Tyr, by incorporating L-tyrosine into the parent framework of Co-MOF-74 (Fig. 10a). The composite packed HPLC columns exhibited excellent performance for the various chiral drugs and drug intermediates, such as nitrendipine, nimodipine, benzoin (Fig. 10b).

  Figure 10

  

  Figure 10.  HPLC racemic separation of enantiomers with Co-MOF-74-L-Tyr-based CMOFs. (a) The procedure of fabrication of CMOF based column, (b) SEM images of CMOF and enantioselective performance. Reproduced with permission [117]. Copyright 2021, Elsevier.

  DownLoad: Full-Size Img PowerPoint

  Compared with GC, CMOFs based CSPs for HPLC racemic separation has been recognized as powerful and useful technique, not only with their wide applications but also with its relative simplicity of operation. More impressive is that HPLC is the practical enantioseparation technology enabled by the adoption of large-scale preparative columns in which optical pure isomers can be easily separated and purified in a gram or even a kilogram scale. The applications of CMOF-CSPs in HPLC racemic separation were summarized in Table 2.

  Table 2

  

  Table 2.  Summary of the different CMOFs for LC separation.

  DownLoad: CSV

  4.3 CMOF-CSPs for CEC racemic separation

  CEC is a well-known micro-scaled chromatographic technique endowing with the excellent efficiency of CE and high selectivity of HPLC. The capillary column normally can be divided into three types according to the different internal structure: packed, monolithic, and open-tubular (OT) columns. In recent years, the application of CMOFs as chromatographic CSPs in CEC system has been confirmed to be the most attractive method for enantioseparating plenty of racemates, showing the satisfactory reproducibility and effective capacity. In this section, CMOF-CSPs for CEC racemic separation will be showcased in chronological order.

  In 2014, Yuan et al. [118] first successfully explored the utilization of a homochiral helical CMOF, namely [Zn₂(D-Cam)₂(4,4′-bpy)]_n, as the chromatographic CSP in OT-CEC for racemic separation of compounds and isomers. First, the homochiral helical was synthesized by the addition of Zn(NO₃)₂·6H₂O, 4,4′-bipyridine, and chiral additive D-camphoric acid in which composed of homochiral layers with pillars of bipyridine ligands, creating two kinds of 3D six connected self-permeable structures. Second, the CMOF was assembled on the sodium silicate layer via a sample procedure. The racemic separation of flavanone and praziquantel were performed on the developed CEC system with high resolution of more than 2.0, hinting excellent enantioselective recognition ability. Yuan et al. [119] reported the second example that a CMOF as the CSP in packed-CEC system for racemic separation of compounds and isomers. The fabricated CEC system gave fast racemic separation within 3 min. The results showed that CMOFs are useful and powerful for fast enantioseparation in CEC. In 2015, Chen et al. [120] synthesized homochiral MOF (AlaZnCl) and assembled on the inner wall of silica capillary by an in situ, layer-by-layer self-assembly approach at room temperature, showing excellent racemic separation efficiency.

  A few years later, Chen et al. [121] also contributed a lot in this work. In his group, a simple and facile synthesis approach was developed to in situ fabricate homochiral MOF [Zn(s-nip)₂]_n in the capillary inner wall by using zinc oxide nanoparticles as efficient nucleating agents for CEC racemic separation. Remarkably, the baseline separations were achieved with high separation resolution. In 2018, Chen et al. [122] continuously utilized a novel homochiral zeolite-like MOF JLU-Liu23 with unique DNA like double-helicity structure as the CSP in CEC system for racemic separation.

  From 2019 to 2020, Du et al. [123] established a novel CEC racemic separation system based on the HKUST-1@capillary with carboxymethyl-β-cyclodextrin (CM-β-CD) as chiral additive. The significantly improved resolution of five basic drugs was obtained in the HKUST-1@CM-β-CD CEC system compared with fused bare capillary column. The mechanism can be ascribed to that the CMOF possess dimensional square-shaped cube and the hydrophobic interaction. The simple cubic symmetry pore network was assembled in the inner wall of HKUST-1@capillary, containing many square channels with channel system (9 × 9 Å). Chen and colleagues [124] reported that the polydopamine-loaded γ-CD metal-organic skeleton was synthesized and utilized as a novel chromatographic CSP for CEC system. The capillary modified with γ-CD metal-organic skeleton showed excellent performance for racemic separating a wide range of racemates. More impressive is that the developed column hinted excellent stability and reproducibility. In the same year, Du et al. [125] used polymer monoliths as a support to grow a zeolitic imidazolate framework-8 (ZIF-8) via layer-by-layer self-assembly. Pepsin, acting as the chiral additive, was covalently assembled into the surface of the amino-modified ZIF-8 through the Schiff base method. The developed column was utilized to the racemic separation of plenty of hydroxychloroquine, chloroquine, hydroxyzine, nefopam, clenbuterol and amlodipine, achieving high separation efficiency. In the same group, another CEC racemic separation system was fabricated, basing on the ZIF-90 modified capillary column with lactobionic acid (LA) as chiral additive [126]. The separation resolution of five racemic drugs was significantly improved in the LA@ZIF-90 capillary system (Fig. S3 in Supporting Information).

  In 2021, Du et al. [127] prepared cellulase@UiO-66-NH₂-incorporated organic polymer monolith column by thermal polymerization. By virtue of the superior physical and chemical properties, the cellulase was then assembled inside UiO-66-NH₂-modified organic monolith via the condensation reaction. The developed monolith column was applied to enantiomerically separate the basic racemic of metoprolol, atenolol, esmolol, bisoprolol and propranolol, obtaining the improved separation resolution. Chen et al. [128] developed a homochiral MOF L-His-NH@MIL-53-based capillary column for racemic separation by CEC. In this work, a facile post-synthetic modification strategy was implemented to functionalize a homochiral MOF, exhibiting high enantioselectivity for several racemic drugs. Chu et al. [129] established a novel kind of chiral OT column with homochiral ZIF-8 nanomaterials using L-histidine as the chiral additive (l-His@ZIF-8). The prepared chiral OT columns have been successfully applied to the separation plenty of enantiomers, providing a potential way for racemic separation (Fig. 11a). The fabricated CEC system achieved the baseline separation of hydroxychloroquine, chloroquine and hydroxyzine enantiomers (Fig. 11b).

  Figure 11

  

  Figure 11.  Enantioselective CEC separation of racemates with pepsin@ZIF-8. (a) The procedure of fabrication of OT column, (b) chromatograms of enantioselective performance. Reproduced with permission [129]. Copyright 2021, Springer.

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  Currently, in 2022, Du et al. [130] prepared a new capillary monolithic column by combining the characteristics of MOF-5 and pepsin for racemic separation in CEC. The ultimate pepsin@MOF-5 capillary column was applied for enantioseparation of diverse racemates in CEC system, achieving excellent resolution and repeatability (Fig. 12). Compared with the merely pepsin assembled monolithic column, the pepsin@MOF-5 modified column exhibited significantly superior enantiomeric resolution, revealing that mixed CSPs capillary monolithic columns facilitate a promising application. Soon afterward, Qin et al. [131] synthesized two kinds of permanently chiral zirconium-based MOFs, namely L-Cys-PCN-222, using L-cysteine as a chiral additive by a solvent-assisted ligand incorporation approach and utilized as the CSPs in the CEC system, respectively. The results revealed that L-Cys-PCN-222-based capillary column showed good performance toward diverse chiral compounds, such as basic amino acids and imidazolinone. In 2023, Tang et al. reported [132] a novel chiral porous column by lipase immobilized MIL-100(Fe) biocomposites (lipase@MIL-101) as CSP through covalent coupling and applied to CEC racemic separation. The performance of the porous column was evaluated by racemic separating amino acid enantiomers, affording high resolution over 2.0.

  Figure 12

  

  Figure 12.  The fabrication of pepsin@MOF-5 for enantioseparation. Reproduced with permission [130]. Copyright 2022, Elsevier.

  DownLoad: Full-Size Img PowerPoint

  In the CEC chromatographic system, the effects of the chiral microenvironment on the properties of the CMOFs and enantiomers are complex. The shape/size matching and enantioselective interactions between the enantiomers and topological structures are the main point for the excellent performance of racemates. This indicates that CMOFs used as the chromatographic CSPs provides an efficient platform for racemic separation system of CEC. The applications of CSPs in CEC separation system were summarized in Table 3.

  Table 3

  

  Table 3.  Summary of the different CMOFs for CEC enantiomeric separation.

  DownLoad: CSV

  5. Concluding remarks and future prospects

  The inherent chirality, remarkable ability, and ease of fabrication of CMOFs facilitate the development of plenty of functional materials for enantioselective applications. The prominent properties of CMOFs are attributed to the infinite structural diversity, manageable chiral cavities, excessive enantiopurity, specific crystalline, perfect tunability, and controllable designability. In this review, we thoroughly summarized the principles of synthetic strategies, mechanism of chiral microenvironment, and the state-of-the-art achievements of CMOFs in wide range of enantioselective applications with the main space being assigned to chromatographic racemic separation.

  Despite the advances in CMOFs for chromatographic racemic separation (HPLC, GC and CEC), challenges as well as perspectives still remain. It is obvious that the challenges in this field lies on the adaption of suitable components for the construction of desirable CMOFs, bearing appropriate chiral architectures, stable pore structures, abundant and useable active recognition sites, as well as accessible chiral channels or pockets. More importantly, from a practical application point of view, the challenge remains the large-scale synthesis of highly stable, easily available and low-cost CMOF materials. The difficulty of CMOF in chromatographic enantioseparation in which is still in the small-scale experimental stage. In addition, the further understanding of racemic separation need to excavate and strengthen. The perspectives are understandable that CMOFs will become, one of the important class of materials in chiral chromatographic technology for large-scale production of pure enantiomers. Further, the theoretical simulation calculation will play a significant role in the design and fabrication of multi-functional CMOFs with high enantioselective capability and the exploration of separation mechanism. More impressive is that the preparation of stable, highly stereoselective, high throughput and eco-friendly CMOF materials and the strengthening of practically enantioselective applications will be the direction of future research.

  Declaration of competing interests

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  CRediT authorship contribution statement

  Genlin Sun: Funding acquisition, Methodology, Project administration, Visualization, Writing – original draft, Data curation, Validation. Yachun Luo: Writing – original draft. Zhihong Yan: Visualization, Software. Hongdeng Qiu: Supervision. Weiyang Tang: Resources, Writing – review & editing.

  Acknowledgment

  This research was supported by the Science and Technology Project of Education Department of Jiangxi Province (No. GJJ201249).

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2024.109787.

  
  
• 1. [1]

     J.C. Worch, H. Prydderch, S. Jimaja, et al., Nat. Rev. Chem. 3 (2019) 514–535. doi: 10.1038/s41570-019-0117-z

  2. [2]

     C.J. Welch, Chirality 32 (2020) 961–974. doi: 10.1002/chir.23234

  3. [3]

     H. Li, X.P. Wang, C.X. Shi, et al., Chin. Chem. Lett. 34 (2023) 107606. doi: 10.1016/j.cclet.2022.06.029

  4. [4]

     X.L. Zhao, S.Q. Zang, X.Y. Chen, Chem. Soc. Rev. 49 (2020) 2481–2503. doi: 10.1039/d0cs00093k

  5. [5]

     M. Yoon, R. Srirambalaji, K. Kim, Chem. Rev. 112 (2012) 1196–1231. doi: 10.1021/cr2003147

  6. [6]

     X. Qiu, J. Ke, W.B. Chen, et al., J. Membrane Sci. 660 (2022) 120870. doi: 10.1016/j.memsci.2022.120870

  7. [7]

     N. Casado, J.V. Traverso, M.A. García, M.L. Marina, Crit. Rev. Anal. Chem. 50 (2020) 554–584. doi: 10.1080/10408347.2019.1670043

  8. [8]

     C.X. Shi, H. Li, X.F. Shi, L. Zhao, H.D. Qiu, Chin. Chem. Lett. 33 (2022) 3613–3622. doi: 10.1016/j.cclet.2021.12.010

  9. [9]

     L. Li, X.Q. Xue, H.G. Zhang, et al., Chin. Chem. Lett. 32 (2021) 2139–2142. doi: 10.1016/j.cclet.2020.11.022

  10. [10]

      J. Chen, N. Yuan, D.N. Jiang, et al., Chin. Chem. Lett. 32 (2021) 3398–3401. doi: 10.1016/j.cclet.2021.04.052

  11. [11]

      T.B. Hua, C. Xiao, Q.Q. Yang, J.R. Chen, Chin. Chem. Lett. 31 (2020) 311–323. doi: 10.1016/j.cclet.2019.07.015

  12. [12]

      X.P. Wang, H. Li, K.J. Quan, et al., Talanta 225 (2021) 121987. doi: 10.1016/j.talanta.2020.121987

  13. [13]

      X.L. Lu, Y. Li, J.T. Yang, Y. Wang, Chin. Chem. Lett. 34 (2023) 108342. doi: 10.1016/j.cclet.2023.108342

  14. [14]

      V. Schurig, J. Chromatogr. A 906 (2001) 275–299. doi: 10.1016/S0021-9673(00)00505-7

  15. [15]

      Q.J. Peng, J.J. Yang, Chin. Chem. Lett. 25 (2014) 1416–1418. doi: 10.1016/j.cclet.2014.05.052

  16. [16]

      J.Y. Zhang, S. Li, L.P. Yao, et al., Chin. Chem. Lett. 34 (2023) 107750. doi: 10.1016/j.cclet.2022.107750

  17. [17]

      H. Liu, Z.H. Wu, J. Chen, J.H. Wang, H.D. Qiu, J. Chromatogr. A 1708 (2023) 464367. doi: 10.1016/j.chroma.2023.464367

  18. [18]

      J.Y. Zhang, S. Li, L.P. Yao, et al., Chin. Chem. Lett. 34 (2023) 898–902.

  19. [19]

      Z.L. Huang, Q. Xu, X.Y. Hu, Chin. Chem. Lett. 31 (2020) 2495–2498. doi: 10.1016/j.cclet.2020.06.017

  20. [20]

      C.H. Liu, K.J. Quan, J. Chen, X.F. Shi, H.D. Qiu, J. Chromatogr. A 1700 (2023) 464032. doi: 10.1016/j.chroma.2023.464032

  21. [21]

      F.H. Mu, B.L. Dai, W. Zhao, et al., Chin. Chem. Lett. 31 (2020) 1773–1781. doi: 10.1016/j.cclet.2019.12.015

  22. [22]

      Y.H. Wang, Q. Li, W. Shi, P. Cheng, Chin. Chem. Lett. 31 (2020) 1768–1772. doi: 10.1016/j.cclet.2020.01.010

  23. [23]

      L.J. Song, H.J. Zhang, T.P. Cai, et al., Chin. Chem. Lett. 30 (2019) 863–866. doi: 10.1016/j.cclet.2018.10.040

  24. [24]

      Y.B. Yu, Y.Q. Ren, W. Shen, H.M. Deng, Z.Q. Gao, Trends Anal. Chem. 50 (2013) 33–41. doi: 10.1016/j.trac.2013.04.014

  25. [25]

      D.X. Ma, B.Y. Li, Z. Shi, Chin. Chem. Lett. 29 (2018) 827–830. doi: 10.1016/j.cclet.2017.09.028

  26. [26]

      C.Q. Cui, G.D. Li, Z.Y. Tang, Chin. Chem. Lett. 32 (2021) 3307–3321. doi: 10.1016/j.cclet.2021.04.001

  27. [27]

      Y.P. Xia, C.X. Wang, M.H. Yu, X.H. Bu, Chin. Chem. Lett. 32 (2021) 1153–1156. doi: 10.1016/j.cclet.2020.09.014

  28. [28]

      L.E. Kreno, K. Leong, O.K. Farha, et al., Chem. Rev. 112 (2012) 1105–1125. doi: 10.1021/cr200324t

  29. [29]

      K.X. Ma, J. Li, H.Y. Ma, et al., Chin. Chem. Lett. 34 (2023) 108227. doi: 10.1016/j.cclet.2023.108227

  30. [30]

      Y. Wang, Q. Li, M.S. Deng, K.J. Chen, J.M. Wang, Chin. Chem. Lett. 33 (2022) 324–327. doi: 10.1016/j.cclet.2021.06.080

  31. [31]

      P. Ramaswamy, N.E. Wong, G.K.H. Shimizu, Chem. Soc. Rev. 43 (2014) 5913–5932. doi: 10.1039/C4CS00093E

  32. [32]

      L. Sun, M.G. Campbell, M. Dinca, Angew. Chem. Int. Ed. 55 (2016) 3566–3579. doi: 10.1002/anie.201506219

  33. [33]

      Z.S. Han, W. Shi, P. Cheng, Chin. Chem. Lett. 29 (2018) 819–822. doi: 10.1016/j.cclet.2017.09.050

  34. [34]

      W. Gong, Z.J. Chen, J.Q. Dong, Y. Liu, Y. Cui, Chem. Rev. 122 (2022) 9078–9144. doi: 10.1021/acs.chemrev.1c00740

  35. [35]

      Y.P. Jiang, X.H. Fang, Z.Q. Zhang, et al., Chin. Chem. Lett. 34 (2023) 108426. doi: 10.1016/j.cclet.2023.108426

  36. [36]

      Y. Liu, X.B. Xi, C.C. Ye, et al., Angew. Chem. Int. Ed. 53 (2014) 13821–13825. doi: 10.1002/anie.201408896

  37. [37]

      Y.W. Peng, T.F. Gong, Y. Cui, Chem. Commun. 49 (2013) 8253–8255. doi: 10.1039/c3cc43549k

  38. [38]

      R.E. Morris, X. Bu, Nat. Chem. 2 (2010) 353–361. doi: 10.1038/nchem.628

  39. [39]

      Q.S. Cheng, Q. Ma, H.B. Pei, et al., Coord. Chem. Rev. 484 (2023) 215120. doi: 10.1016/j.ccr.2023.215120

  40. [40]

      S.M. Xie, X. Chen, J. Zhang, L.M. Yuan, TrAC, Trends Anal. Chem. 124 (2020) 115808. doi: 10.1016/j.trac.2020.115808

  41. [41]

      X.K. Wang, J.H. Zhang, A.J. Yu, et al., Microchem. J. 174 (2022) 107092. doi: 10.1016/j.microc.2021.107092

  42. [42]

      C.F. Zhu, A.M. Zhang, Y. Li, et al., Inorg. Chem. Front. 9 (2022) 2683–2l690. doi: 10.1039/d2qi00152g

  43. [43]

      A. Berthod, Anal. Chem. 78 (2006) 2093–2099. doi: 10.1021/ac0693823

  44. [44]

      E. Mamontova, P. Trens, F. Salles, et al., Inorg. Chem. Front. 6 (2019) 3245–3254. doi: 10.1039/c9qi00837c

  45. [45]

      G.K.E. Scriba, Methods Mol. Biol. 1985 (2019) 1–33. doi: 10.1007/978-1-4939-9438-0_1

  46. [46]

      K.J. Hartlieb, J.M. Holcroft, P.Z. Moghadam, et al., J. Am. Chem. Soc. 138 (2016) 2292–2301. doi: 10.1021/jacs.5b12860

  47. [47]

      H.D. Flack, Helv. Chim. Acta 86 (2003) 905–921. doi: 10.1002/hlca.200390109

  48. [48]

      Z.G. Gu, C. Zhan, J. Zhang, X. Bu, Chem. Soc. Rev. 45 (2016) 3122–3144. doi: 10.1039/C6CS00051G

  49. [49]

      Z.X. Xu, L. Liu, J. Zhang, Inorg. Chem. 55 (2016) 6355–6357. doi: 10.1021/acs.inorgchem.6b00865

  50. [50]

      L.J. Dong, W. Chu, Q.L. Zhu, R.D. Huang, Cryst. Growth Des. 11 (2011) 93–99. doi: 10.1021/cg1009175

  51. [51]

      Z.X. Xu, Y. Xiao, Y. Kang, L. Zhang, J. Zhang, Cryst. Growth. Des. 15 (2015) 4676–4686. doi: 10.1021/acs.cgd.5b00958

  52. [52]

      E. Yang, L. Wang, F. Wang, et al., Inorg. Chem. 53 (2014) 10027–10029. doi: 10.1021/ic501556w

  53. [53]

      J.S. Seo, D. Whang, H. Lee, et al., Nature 404 (2000) 982–986. doi: 10.1038/35010088

  54. [54]

      E.V. Anokhina, A.J. Jacobson, J. Am. Chem. Soc. 126 (2004) 3044–3045. doi: 10.1021/ja031836f

  55. [55]

      E.V. Anokhina, Y.B. Go, Y. Lee, T. Vogt, A.J. Jacobson, J. Am. Chem. Soc. 128 (2006) 9957–9962. doi: 10.1021/ja062743b

  56. [56]

      W. Gong, Y. Liu, Y. Cui, Faraday Discuss. 231 (2021) 168–180. doi: 10.1039/d1fd00014d

  57. [57]

      S.C. Sahoo, T. Kundu, R. Banerjee, J. Am. Chem. Soc. 133 (2011) 17950–17958. doi: 10.1021/ja2078637

  58. [58]

      M.N. Corella-Ochoa, J.B. Tapia, H.N. Rubin, et al., J. Am. Chem. Soc. 141 (2019) 14306–14316. doi: 10.1021/jacs.9b06500

  59. [59]

      J.M. Falkowski, T. Sawano, T. Zhang, et al., J. Am. Chem. Soc. 136 (2014) 5213–5216. doi: 10.1021/ja500090y

  60. [60]

      S.J. Garibay, Z. Wang, K.K. Tanabe, S.M. Cohen, Inorg. Chem. 48 (2009) 7341–7349. doi: 10.1021/ic900796n

  61. [61]

      Z. Feng, C. Wu, W.M. Liao, L.H. Chung, J. He, Inorg. Chem. Commun. 131 (2021) 108791. doi: 10.1016/j.inoche.2021.108791

  62. [62]

      D.J. Lun, G.I.N. Waterhouse, S.G. Telfer, J. Am. Chem. Soc. 133 (2011) 5806–5809. doi: 10.1021/ja202223d

  63. [63]

      X.D. Hou, T.T. Xu, Y. Wang, et al., ACS Appl. Mater. Interfaces 37 (2017) 32264–32269. doi: 10.1021/acsami.7b10147

  64. [64]

      Z.S. Han, K.Y. Wang, Y.F. Guo, et al., Nat. Commun. 10 (2019) 5117. doi: 10.1038/s41467-019-13090-9

  65. [65]

      C.X. Tan, X. Han, Z.J. Li, Y. Liu, Y. Cui, J. Am. Chem. Soc. 140 (2018) 16229. doi: 10.1021/jacs.8b09606

  66. [66]

      X.J. Hu, G. Huang, S. Zhang, et al., Chem. Commun. 56 (2020) 7459. doi: 10.1039/d0cc03349a

  67. [67]

      E.Q. Gao, S.Q. Bai, Z.M. Wang, C.H. Yan, J. Am. Chem. Soc. 125 (2003) 4984–4985. doi: 10.1021/ja034129v

  68. [68]

      E.Q. Gao, Y.F. Yue, S.Q. Bai, Z. He, C.H. Yan, J. Am. Chem. Soc. 126 (2004) 1419–1429. doi: 10.1021/ja039104a

  69. [69]

      X. Tan, J. Zhan, J. Zhang, L. Jiang, M. Pan, C.Y. Su, CrystEngComm 14 (2012) 63–66. doi: 10.1039/C1CE05995E

  70. [70]

      Q. Wen, M.C. Gregorio, L.J.W. Shimon, et al., Chem. Eur. J. 28 (2022) e202201108. doi: 10.1002/chem.202201108

  71. [71]

      X.L. Luo, Y. Cao, T. Wang, et al., J. Am. Chem. Soc. 138 (2016) 786–789. doi: 10.1021/jacs.5b12516

  72. [72]

      D. Wu, K. Zhou, J. Tian, et al., Angew. Chem. Int. Ed. 133 (2021) 3124–3131. doi: 10.1002/ange.202013885

  73. [73]

      K.K. Bisht, E. Suresh, J. Am. Chem. Soc. 135 (2013) 15690–15693. doi: 10.1021/ja4075369

  74. [74]

      Y.H. Wen, T.L. Sheng, Z.H. Sun, et al., Chem. Commun. 50 (2014) 8320–8323. doi: 10.1039/c4cc03478c

  75. [75]

      X. Zhao, E.T. Nguyen, A.N. Hong, P. Feng, X. Bu, Angew. Chem. Int. Ed. 57 (2018) 7101–7105. doi: 10.1002/anie.201802911

  76. [76]

      B. Wang, X.Z. Wang, D. Luo, X.P. Zhou, D. Li, J. Coord. Chem. 75 (2022) 11–14.

  77. [77]

      S.M. Xie, Z.J. Zhang, Z.Y. Wang, L.M. Yuan, J. Am. Chem. Soc. 133 (2011) 11892–11895. doi: 10.1021/ja2044453

  78. [78]

      S.M. Xie, X.H. Zhang, Z.J. Zhang, L.M. Yuan, Anal. Lett. 46 (2013) 753–763. doi: 10.1080/00032719.2012.735306

  79. [79]

      S.M. Xie, X.H. Zhang, Z.J. Zhang, et al., Anal. Bioanal. Chem. 405 (2013) 3407–3412. doi: 10.1007/s00216-013-6714-7

  80. [80]

      X. Zhang, S.M. Xie, A. Duan, B. Wang, L.M. Yuan, Chromatographia 76 (2013) 831–836. doi: 10.1007/s10337-013-2484-9

  81. [81]

      S.M. Xie, X. Zhang, B. Wang, et al., Chromatographia 77 (2014) 1359–1365. doi: 10.1007/s10337-014-2719-4

  82. [82]

      S.M. Xie, B. Wang, X. Zhang, et al., Chirality 26 (2014) 27–32. doi: 10.1002/chir.22260

  83. [83]

      X. Xue, M. Zhang, S.M. Xie, L.M. Yuan, Acta Chromatogr. 27 (2015) 15–26. doi: 10.1556/AChrom.27.2015.1.2

  84. [84]

      Z.G. Gu, W.Q. Fu, X. Wu, J. Zhang, Chem. Commun. 52 (2016) 772–775. doi: 10.1039/C5CC07614E

  85. [85]

      L. Li, S.M. Xie, J. Zhang, et al., Chem. Res. Chin. Univ. 33 (2017) 24–30. doi: 10.1007/s40242-017-6270-3

  86. [86]

      J. Yang, S.M. Xie, J. Zhang, et al., J. Chromatogr. Sci. 54 (2016) 1467–1474. doi: 10.1093/chromsci/bmw111

  87. [87]

      H. Liu, S.M. Xie, P. Ai, et al., Chempluschem 79 (2014) 1103–1108. doi: 10.1002/cplu.201402067

  88. [88]

      J. Yang, S.M. Xie, H. Liu, J. Zhang, L.M. Yuan, Chromatographia 78 (2015) 557–564. doi: 10.1007/s10337-015-2863-5

  89. [89]

      S.Y. Zhang, C.X. Yang, W. Shi, et al., Chem 3 (2017) 281–289. doi: 10.1016/j.chempr.2017.07.004

  90. [90]

      D.D. Zheng, Y. Zhang, L. Wang, M. Kurmoo, M.H. Zeng, Inorg. Chem. Commun. 82 (2017) 34–38. doi: 10.1016/j.inoche.2017.05.013

  91. [91]

      W.T. Kou, C.X. Yang, X.P. Yan, J. Mater. Chem. A 6 (2018) 17861–17866. doi: 10.1039/c8ta06804f

  92. [92]

      A.L. Nuzhdin, D.N. Dybtsev, K.P. Bryliakov, E.P. Talsi, V.P. Fedin, J. Am. Chem. Soc. 129 (2007) 12958–12959. doi: 10.1021/ja076276p

  93. [93]

      M. Padmanaban, P. Muller, C. Lieder, et al., Chem. Commun. 47 (2011) 12089–12091. doi: 10.1039/c1cc14893a

  94. [94]

      K. Tanaka, T. Muraoka, D. Hirayama, A. Ohnish, Chem. Commun. 48 (2012) 8577–8579. doi: 10.1039/c2cc33939k

  95. [95]

      M. Zhang, Z.J. Pu, X.L. Chen, et al., Chem. Commun. 49 (2013) 5201–5203. doi: 10.1039/c3cc41966e

  96. [96]

      Y.W. Peng, T.F. Gong, K. Zhang, et al., Nat. Commun. 5 (2014) 4406. doi: 10.1038/ncomms5406

  97. [97]

      M. Zhang, J.H. Zhang, Y. Zhang, et al., J. Chromatogr. A 1325 (2014) 163–170. doi: 10.1016/j.chroma.2013.12.023

  98. [98]

      M. Zhang, X.D. Xue, J.H. Zhang, et al., Anal. Methods 6 (2014) 341–346. doi: 10.1039/C3AY41068D

  99. [99]

      X. Kuang, Y. Ma, H. Su, et al., Anal. Chem. 86 (2014) 1277–1281. doi: 10.1021/ac403674p

  100. [100]

       S.A. Boer, Y. Nolvachai, C. Kulsing, et al., Chem. Eur. J. 20 (2014) 11308–11312. doi: 10.1002/chem.201404047

  101. [101]

       J. Kong, M. Zhang, A.H. Duan, et al., J. Sep. Sci. 38 (2015) 556–561. doi: 10.1002/jssc.201401034

  102. [102]

       R. Hailili, L. Wang, J. Qv, et al., Inorg. Chem. 54 (2015) 3713–3715. doi: 10.1021/ic502861k

  103. [103]

       K. Tanaka, N. Hotta, S. Nagase, K. Yoza, New J. Chem. 40 (2016) 4891–4894. doi: 10.1039/C6NJ00090H

  104. [104]

       C. Hu, L. Li, N. Yang, et al., Acta Chim. Sin. 74 (2016) 819–824. doi: 10.6023/A16070349

  105. [105]

       J.H. Zhang, R.Y. Nong, S.M. Xie, et al., Electrophoresis 38 (2017) 2513–2520. doi: 10.1002/elps.201700122

  106. [106]

       C.X. Yang, Y.Z. Zheng, X.P. Yan, RSC Adv. 7 (2017) 36297–36301. doi: 10.1039/C7RA06558B

  107. [107]

       S.M. Xie, C.H. Hu, L. Li, et al., Microchem. J. 139 (2018) 487–491. doi: 10.1016/j.microc.2018.03.035

  108. [108]

       Y.Y. Yu, N.Y. Xu, J.H. Zhang, et al., ACS Appl. Mater. Interfaces 12 (2020) 16903–16911. doi: 10.1021/acsami.0c01023

  109. [109]

       C.J. Wang, L. Zhang, X.L. Li, A. Yu, S. Zhang, Talanta 218 (2020) 121155. doi: 10.1016/j.talanta.2020.121155

  110. [110]

       N.Y. Xu, B.Y. Yuan, C. Hu, et al., J. Anal. Chem. 76 (2021) 749–754. doi: 10.1134/s1061934821060149

  111. [111]

       B.Y. Yuan, L. Li, Y.Y. Yu, et al., Microchem. J. 161 (2021) 105815. doi: 10.1016/j.microc.2020.105815

  112. [112]

       J.K. Chen, Y.Y. Yu, N.Y. Xu, et al., Microchem. J. 169 (2021) 106576. doi: 10.1016/j.microc.2021.106576

  113. [113]

       Y.Y. Yu, B.Y. Yuan, C. Hu, et al., J. Chromatogr. Sci. 59 (2021) 355–360. doi: 10.1093/chromsci/bmaa117

  114. [114]

       J.K. Chen, N.Y. Xu, P. Guo, et al., J. Sep. Sci. 44 (2021) 3976–3985. doi: 10.1002/jssc.202100557

  115. [115]

       H. Jiang, K.W. Yang, X.X. Zhao, et al., J. Am. Chem. Soc. 143 (2021) 390–398. doi: 10.1021/jacs.0c11276

  116. [116]

       Y.R. Lu, Y.Y. Yu, J.K. Chen, et al., J. Sep. Sci. 45 (2022) 3510–3519. doi: 10.1002/jssc.202200366

  117. [117]

       X. Ma, Y. Guo, L. Zhang, et al., Talanta 239 (2022) 123143. doi: 10.1016/j.talanta.2021.123143

  118. [118]

       Z.X. Fei, M. Zhang, J.H. Zhang, L.M. Yuan, Anal. Chim. Acta 830 (2014) 49–55. doi: 10.1016/j.aca.2014.04.054

  119. [119]

       Z.X. Fei, M. Zhang, S.M. Xie, L.M. Yuan, Electrophoresis 35 (2014) 3541–3548. doi: 10.1002/elps.201400227

  120. [120]

       C.J. Pan, W.F. Wang, H.G. Zhang, L.F. Xu, X.G. Chen, J. Chromatogr. A 1388 (2015) 207–216. doi: 10.1016/j.chroma.2015.02.034

  121. [121]

       C.J. Pan, W.F. Wang, X.G. Chen, J. Chromatogr. A 1427 (2016) 125–133. doi: 10.1016/j.chroma.2015.12.020

  122. [122]

       C.J. Pan, W. Lv, X. Niu, et al., J. Chromatogr. A 1541 (2018) 31–38. doi: 10.1016/j.chroma.2018.02.015

  123. [123]

       X.D. Sun, Y. Tao, Y.X. Du, et al., Microchim. Acta 186 (2019) 462. doi: 10.1007/s00604-019-3584-5

  124. [124]

       Z.T. Li, Z.K. Mao, W. Zhou, Z.L. Chen, Talanta 218 (2020) 121160. doi: 10.1016/j.talanta.2020.121160

  125. [125]

       W. Ding, T. Yu, Y.X. Du, et al., Microchim. Acta 187 (2020) 51. doi: 10.1007/s00604-019-3998-0

  126. [126]

       W. Ding, M.X. Ma, Y.X. Du, C. Chen, X.F. Ma, Microchim. Acta 187 (2020) 651. doi: 10.1007/s00604-020-04611-1

  127. [127]

       M.X. Ma, J. Zhang, P.P. Li, et al., Microchim. Acta 188 (2021) 186. doi: 10.1007/s00604-021-04840-y

  128. [128]

       X.D. Sun, B. Niu, Q. Zhang, Q. Chen, J. Pharm. Anal. 12 (2022) 509–516. doi: 10.1016/j.jpha.2021.12.004

  129. [129]

       T.T. Wang, L. Yang, Y.H. Cheng, et al., Microchim. Acta 188 (2021) 375. doi: 10.1007/s00604-021-05030-6

  130. [130]

       P.D. Miao, L. Zhang, J. Zhang, et al., J. Chromatogr. B 1203 (2022) 123306. doi: 10.1016/j.jchromb.2022.123306

  131. [131]

       L.L. Gao, X.F. Hu, S.L. Qin, et al., RSC Adv. 12 (2022) 6063–6075. doi: 10.3390/app12126063

  132. [132]

       G.L. Sun, D.M. Choi, H.L. Xu, et al., Microchim. Acta 190 (2023) 84. doi: 10.1007/s00604-023-05647-9

• 

  Figure 1  (a) Crystal structure of 3D Zn-CMOFs with unh-topology. Reproduced with permission [57]. Copyright 2011, American Chemical Society. (b) Crystal structure of Cu(H₂O)₂(S-TA)₂]·6H₂O. Reproduced with permission [58]. Copyright 2019, American Chemical Society. (c) Crystal structure of BINAP-MOF. Reproduced with permission [59]. Copyright 2014, American Chemical Society.

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  Figure 2  (a) Crystal structure of IRMOF-3. Reproduced with permission [60]. Copyright 2009, American Chemical Society. (b) Crystal structure of MeOBim-Zn. Reproduced with permission [61]. Copyright 2021, Elsevier. (c) Crystal structure of IRMOF-Pro-Boc. Reproduced with permission [62]. Copyright 2011, American Chemical Society. (d) Crystal structure of Cu₃(Btc)₂]@[Cu₂(D-Cam)₂. Reproduced with permission [63]. Copyright 2017, American Chemical Society.

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  Figure 3  (a) Crystal structure of Zn-MOF. Reproduced with permission [64]. Copyright 2019, Nature. (b) Crystal structure of Zr-based UiO-68. Reproduced with permission [65]. Copyright 2018, American Chemical Society.

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  Figure 4  (a) Crystal structure of [(Cu₄I₄)(dabco)₂]·[Cu₂(bbimb)]·3DMF. Reproduced with permission [71]. Copyright 2016, American Chemical Society. (b) Crystal structure of FJI-H16 and FJI-H27. Reproduced with permission [72]. Copyright 2021, Wiley. (c) Crystal structure of [Zn(SO₄)(L)(H₂O)₂]_n. Reproduced with permission [73]. Copyright 2013, American Chemical Society.

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  Figure 5  (a) Crystal structure of 3D MOF. Reproduced with permission [74]. Copyright 2014, Royal Society of Chemistry. (b) Crystal structure of CPM-311 and CPM-312. Reproduced with permission [75]. Copyright 2018, Wiley.

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  Figure 6  The Cu₂(D-Cam)₂dabco@Poly(L-DOPA) for GC separation of racemates. (a) The fabrication of CMOF, (b) the SEM images of inner surface of column, (c) the chromatograms of enantioseparation. Reproduced with permission [84]. Copyright 2016, Royal Society of Chemistry.

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  Figure 7  The CMOF-3S for GC separation of racemates. (a, b) The fabrication of CMOF, (c) the mechanism of chiral binding sites, (d) the chromatograms of enantioseparation. Reproduced with permission [89]. Copyright 2017, Cell.

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  Figure 8  HPLC racemic separation of four kinds of enantiomers. (a) The chiral binding sites, (b) the SEM images of CMOF, (c) the performance of separation racemates. Reproduced with permission [99]. Copyright 2014, American Chemical Society.

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  Figure 9  HPLC racemic separation of enantiomers with robust Zr(Ⅳ)-based CMOFs. (a) The mechanism of CMOF, (b) the performance of enantioseparation. Reproduced with permission [115]. Copyright 2021, American Chemical Society.

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  Figure 10  HPLC racemic separation of enantiomers with Co-MOF-74-L-Tyr-based CMOFs. (a) The procedure of fabrication of CMOF based column, (b) SEM images of CMOF and enantioselective performance. Reproduced with permission [117]. Copyright 2021, Elsevier.

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  Figure 11  Enantioselective CEC separation of racemates with pepsin@ZIF-8. (a) The procedure of fabrication of OT column, (b) chromatograms of enantioselective performance. Reproduced with permission [129]. Copyright 2021, Springer.

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  Figure 12  The fabrication of pepsin@MOF-5 for enantioseparation. Reproduced with permission [130]. Copyright 2022, Elsevier.

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  Table 1.  Summary of the different CMOFs for GC racemic separation.

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  Table 2.  Summary of the different CMOFs for LC separation.

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  Table 3.  Summary of the different CMOFs for CEC enantiomeric separation.

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•