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In this article, chiral covalent organic framework core‐shell composite CCOF‐TpPa‐Py@SiO2 was facilely synthesized by induction at room temperature. The CCOF‐TpPa‐Py@SiO2 core‐shell composite was used as a chiral stationary phase for the separation of the racemates by high‐performance liquid chromatography, which exhibits good separation performance for chiral compounds including ketones, alcohols, esters, epoxides, carboxylic acids, amides, and amines. The effects of analyte injection mass on the enantioseparation were studied. The reproducibility and stability of the CCOF‐TpPa‐Py@SiO2 chiral column were explored. The intra‐day (n = 5), inter‐day (n = 5), and inter‐column (n = 3) relative standard deviations for the migration times and resolution of benzoin were 0.32%–0.54%, 0.45%–0.61%, and 1.21%–1.53%, respectively. In addition, the chiral separation ability of the CCOF‐TpPa‐Py@SiO2 chiral column (column A) was compared with that of the MDI‐β‐CD‐Modified COF@SiO2 (column B) as well as a commercial chiral column (Chiralpak AD‐H). The chiral recognition ability of column A is complementary to that of column B and AD‐H column. The resolution mechanism of CCOF‐TpPa‐Py@SiO2 stationary phase towards chiral analyte was explored. Hence, the synthesis of CCOF‐TpPa‐Py@SiO2 core‐shell composite by induction at room temperature as chiral stationary phases for chromatographic separation has important research potential and application prospects. [ABSTRACT FROM AUTHOR]

Chiral covalent triazine frameworks (CCTFs), as emerging chiral organic porous polymer materials, have many special properties, such as being rich in nitrogen, having a large surface area, adjustable porosity, and high chemical stability, etc., making them an attractive separation medium for HPLC enantioseparation. Herein, a novel chiral core–shell composite CC-DMP CCTF@SiO2 with uniform spherical particles was synthesized by an in situ growth method. The prepared chiral core–shell microspheres CC-DMP CCTF@SiO2 were adopted to resolve chiral compounds by HPLC. The results showed that the CC-DMP CCTF@SiO2 packed column exhibited good separation performance and high column efficiency (e.g., 17 580 plates m−1 for 4-methylbenzhydrol) under a low column back pressure (5–9 bar) for HPLC separation of different chiral compounds such as alcohols, amines, ketones, and so on. Among them, the resolution values of naringenin and 1-phenyl-1,2-ethanediol were 4.24 and 4.09, respectively. Comparing the chiral recognition capacity of the CC-DMP CCTF@SiO2 packed column with those of commercial Chiralpak AD-H and the previously reported CCOFs@SiO2 (CTpBD@SiO2, β-CD-COF@SiO2) columns, the CC-DMP CCTF@SiO2 packed column can be complementary to the Chiralpak AD-H and CCOFs@SiO2 columns. The effects of the injection amount and column temperature on the separation process were also studied. The CC-DMP CCTF@SiO2 packed column exhibited good reproducibility and stability after multiple injections. The relative standard deviations (RSDS) of the retention time and peak area for repeated separation of 4-methylbenzhydrol (n = 5) were 0.45% and 0.87%, respectively. This work suggests that the chiral CC-DMP CCTF@SiO2 core–shell microsphere composite has a promising application as a novel CSP material in HPLC. [ABSTRACT FROM AUTHOR]

Chiral metal‐organic frameworks have shown great potential in enantioselective separation and asymmetric catalysis due to their diverse and adjustable structures with abundant chiral recognition sites. Herein, a new chiral post‐synthetic modification was used for preparing an achiral@chiral metal‐organic frameworks core‐shell composite [Cu3(Btc)2]@[Cu2((+)‐Cam)2Dabco] by a superficial chiral etching method. The [Cu3(Btc)2]@[Cu2((+)‐Cam)2Dabco] composite was utilized as a novel chiral stationary phase for HPLC enantioseparation. Various racemates were separated on the [Cu3(Btc)2]@[Cu2((+)‐Cam)2Dabco]‐packed column (column A). It exhibited good chiral resolving ability toward many different kinds of racemates, especially chiral drugs. Among them, the highest resolution value for 1,2‐diphenyl‐1,2‐ethanediol reaches 2.70. The relative standard deviations of retention time and peak area for repeated separation of 1,2‐diphenyl‐1,2‐ethanol were 0.45% and 0.81%, respectively. Compared with the resolution ability of [Cu2((+)‐Cam)2Dabco]‐packed column (column B), column A shows higher column efficiency and better separation performance than those of column B. The results indicated that the [Cu3(Btc)2]@[Cu2((+)‐Cam)2Dabco] as a stationary phase can greatly improve the column efficiency and chiral resolution ability of chiral metal‐organic frameworks, which demonstrated that the superficial chiral etching as an economic and efficient strategy opens up a new way for the application of metal‐organic frameworks. [ABSTRACT FROM AUTHOR]

A spherical chiral porous organic polymer (POPs) COP-1 is synthesized by the Friedel–Crafts alkylation reaction of Boc-3-(4-biphenyl)-L-alanine (BBLA) and 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP), which was used as a novel chiral stationary phase (CSPs) for mixed-mode high-performance liquid chromatography (HPLC) enantioseparation. The racemic compounds were resolved in normal-phase liquid chromatography (NPLC) using n-hexane/isopropanol as mobile phase and reversed-phase liquid chromatography (RPLC) using methanol/water as mobile phase. The COP-1-packed column exhibited excellent separation performance toward various racemic compounds including alcohols, amines, ketones, esters, epoxy compounds, organic acids, and amino acids in NPLC and RPLC modes. The effects of analyte mass and column temperature on the separation efficiency of racemic compounds were investigated. In addition, the chiral resolution ability of the COP-1-packed column not only can be complementary in RPLC/NPLC modes but also exhibit a good chiral recognition complementarity with Chiralpak AD-H column and chiral porous organic cage (POC) NC1-R column. The relative standard deviations (RSD) (n = 5) of the retention time, resolution value, and peak area by repeated separation of 1-(4-chiorophenyl)ethanol are all below 3.0%. The COP-1 column shows high column efficiency (e.g., 17,320 plates m−1 for 1-(4-chlorophenyl)ethanol on COP-1 column in NPLC), high enantioselectivity, and good reproducibility toward various racemates. This work demonstrates that chiral POPs microspheres are promising chiral materials for HPLC enantioseparation. [ABSTRACT FROM AUTHOR]

The unique features of uniform and adjustable cavities, abundant chiral active sites, and high enantioselectivity make chiral metal‐organic frameworks popular as an emerging candidate for enantioselective separation. However, the wide particle size distribution and irregular shape of as‐synthesized metal–organic frameworks result in low column efficiency, undesired chromatographic peak shape, and high column backpressure of such metal–organic frameworks packed columns. Herein, we report the fabrication of chiral core‐shell microspheres [Cu2(d‐Cam)2(4,4′‐bpy)]n@SiO2 composite for high‐performance liquid chromatography enantioseparation to overcome the above‐mentioned problems. The [Cu2(d‐Cam)2(4,4′‐bpy)]n@SiO2 packed column gave high‐resolution separation of racemates under low column backpressure (10‐22 bar), indicating its synergistic effect of the good column packing property of the SiO2 microspheres and the chiral recognition ability of [Cu2(d‐Cam)2(4,4′‐bpy)]n crystals. Thirteen kinds of chiral compounds including alcohols, amines, ketones, epoxides, and organic bases were well separated with good peak shapes and high column efficiency (18200 plates/m for 1‐(9‐anthryl)‐2,2,2‐trifluoroethanol) on the [Cu2(d‐Cam)2(4,4′‐bpy)]n@SiO2 packed column. Among them, seven pairs of enantiomers achieved baseline separation and the resolution value for 1‐(9‐anthryl)‐2,2,2‐trifluoroethanol reached 11.22. Some effects such as column temperature, and analytes mass on the enantioseparations have been investigated. In addition, the [Cu2(d‐Cam)2(4,4′‐bpy)]n@SiO2 packed column exhibited good stability and repeatability for the separation of chiral compounds. The relative standard deviations for five replicate separations of 1‐phenylethanol were less than 1.0, 1.5, 3.0, and 2.0% for the retention time, peak area, number of theoretical plates, and resolution, respectively. The research results demonstrated the development of chiral metal–organic frameworks core‐shell microspheres composite provide a promising platform for their practical application in chiral separation fields. [ABSTRACT FROM AUTHOR]

Porous materials with well‐defined pore structures have received considerable attention in the past decades due to their unique structures and wide applications. Most porous materials such as zeolites, metal‐organic frameworks, covalent organic frameworks, and porous organic polymers are extended to infinite frameworks or networks by robust covalent or coordination bonds. Porous molecular cages composed of discrete molecules with permanent cavities are an emerging class of porous material and the discrete molecules assemble into solids by weak intermolecular interaction. In comparison to porous extended solids such as metal‐organic frameworks and covalent organic frameworks, porous molecular cage solids are generally soluble in organic solvents thus allowing solution processing, making them more convenient to apply in many fields. This review mainly focuses on the recent advances of application of porous molecular cages (porous organic cages and metal‐organic cages) for enantioselective recognition and separation from 2010 to present, including gas chromatography, capillary electrochromatography, chiral fluorescent recognition, chiral potentiometric sensing, and enantioselective adsorption. Furthermore, the two important family members of porous molecular cages, porous organic cages and metal‐organic cages, are also discussed. [ABSTRACT FROM AUTHOR]

Chiral mesoporous silica (CMS) has attracted widespread attention because of some unique properties, such as high surface area, uniformly structured nanoscale cavities, and excellent chemical and thermal stability. In this work, we report the utilization of a CMS as the stationary phase for the separation of racemates in gas chromatography (GC). A CMS‐coated capillary column was fabricated by a dynamic coating method. Eighteen racemates belonging to different classes of organic compounds were separated on this column, including chiral alcohols, aldehydes, ketones, organic acids, halohydrocarbons, alkenes, alcohol amines, epoxides, and amino acid derivatives. In addition, linear alkanes, alcohols, and aromatic hydrocarbons have also been resolved. [ABSTRACT FROM AUTHOR]

Abstract: Porous organic cages composed of discrete cage molecules have attracted considerable recent attention as gas adsorption materials and separation media. In this study, we report a homochiral porous organic cage CC5 with a large cavity and pore windows as a novel stationary phase for high‐resolution gas chromatographic separations. The capillary column was prepared by a static coating method. A large number of racemic compounds have been resolved on the coated capillary column, including derivatized amino acids, alcohols, alcohol amines, esters, ethers, ketones, and epoxides. It is interesting that the CC5‐coated capillary column exhibits significant chiral recognition complementarity to a commercial β‐DEX 120 column and a previously reported homochiral porous organic cage CC3‐R‐coated column, which could expand the range of the analytes amenable to separation on porous organic cage‐based capillary columns. Moreover, the fabricated column also shows excellent selectivity for the separation of positional isomers, including the challenging ethylbenzene and xylene isomers. Experimental results demonstrate an excellent separation performance and stability of the CC5‐coated column, making it promising for gas chromatography applications. [ABSTRACT FROM AUTHOR]

A highly ordered chiral mesoporous silica-coated capillary column has been used for high-resolution gas chromatographic separations. The column has excellent selectivity, not only for the separation of isomers, polycyclic aromatic hydrocarbons, linear alkanes, long chain alkanes, Grob’s test mixture and aromatic hydrocarbons, but also for the resolution of different classes of chiral compounds. Additionally, the column exhibits high column efficiency, excellent temperature resistance, and analysis times are short. This is the first report of a highly ordered chiral inorganic mesoporous silica used in separation science. [ABSTRACT FROM AUTHOR]

• A novel BINOL-based chiral polyimine macrocycle bonded silica CSP was prepared. • Excell enantioselectivity of the CSP in both NP-HPLC and RP-HPLC. • Good chiral separation complementarity to Chiralpak AD-H and Chiralcel OD-H columns. • Great potential of BINOL-based chiral macrocycle for HPLC enantioseparation. Macrocycles play vital roles in supramolecular chemistry and chromatography. 1,1′-Bi-2-naphthol (BINOL)-based chiral polyimine macrocycles are an emerging class of chiral macrocycles that can be constructed by one-step aldehyde-amine condensation of BINOL derivatives with other building blocks. These macrocycles exhibit good characteristics, such as facile preparation, rigid cyclic structures, multiple chiral centers, and defined molecular cavities, that make them good candidates as new chiral recognition materials for chromatographic enantioseparations. In this study, a BINOL-based [2+2] chiral polyimine macrocycle was synthesized by one-step condensation of enantiopure (S)-2,2′-dihydroxy-[1,1′-binaphthalene]-3,3′-dicarboxaldehyde with (1R,2R)-1,2-diaminocyclohexane. The product was modified with 5-bromo-1-pentene and then attached to thiolated silica using click chemistry to construct a new chiral stationary phase (CSP). The enantioselectivity of the new CSP was explored by separating various racemates under normal phase (NP) and reversed phase (RP) high performance liquid chromatography (HPLC). Thirteen racemates and eight racemates were enantioseparated under the two separation modes, respectively, including chiral alcohols, phenols, esters, ketones, amines, and organic acids. Among them, nine racemates achieved baseline separation under NP-HPLC and seven racemates achieved baseline separation under RP-HPLC. High resolution separation was observed with benzoin (Rs = 5.10), epinephrine (Rs = 4.98), 3-benzyloxy-1,2-propanediol (Rs = 4.42), and 4,4′-dimethylbenzoin (Rs = 4.52) in NP-HPLC, and with 4-methylbenzhydrol (Rs = 4.72), benzoin ethyl ether (Rs = 3.79), 1-phenyl-1-pentanol (R s = 3.68), and 1-(3-bromophenyl)ethanol (Rs = 3.60) in RP-HPLC. Interestingly, the CSP complemented Chiralcel OD-H, Chiralpak AD-H, and CYCLOBOND I 2000 RSP columns for resolution of these test racemates, separating several racemic compounds that could not be well separated by the three commercially available columns. The influences of injected sample amount on separation were also evaluated. It was found that the column exhibited excellent stability and reproducibility after hundreds of injections, and the relative standard deviations (n = 5) of the retention time and resolution were less than 0.49% and 0.69%, respectively. This study indicates that the BINOL-based chiral macrocycle has great potential for HPLC enantioseparation. [ABSTRACT FROM AUTHOR]

Macrocyclic compounds such as crown ethers and cyclodextrins play an important role in the field of chromatography and show excellent separation performance. The design of simple and convenient methods for the efficient synthesis of novel chiral macrocycles for chromatographic separation is of great significance. In this work, a novel chiral polyimine macrocycle (PIMC) was designed and synthesized by the simply one-step reaction of 2,6-diformyl-4- tert -butylphenol with (S)-(-)-1,2-propanediamine. Then, it was bonded onto silica by the thiol-ene click reaction to construct a new chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). The chiral separation performance of the proposed CSP was examined by separating various racemates in the normal-phase (NP) and reversed-phase (RP) HPLC. In total, twelve and nine racemates, including ethers, esters, amines, alcohols, organic acids, ketones, and epoxides, were separated to varying degrees via NP-HPLC and RP-HPLC, respectively, Moreover, the CSP offered good chiral separation complementarity to Chiralcel OD-H and Chiralpak AD-H columns for resolution of these test racemates, and it can separate several racemic compounds that either cannot be separated or cannot be separated well be separated by the two commercially available columns. After the column was used for hundreds of injections, the relative standard deviations of the retention time and resolution were below 0.56 % and 0.45 %, respectively, showing the good reproducibility and stability of the CSP. This study provides a simple and convenient approach to synthesize a novel chiral macrocycle and CSP and also indicates the broad application prospects of such chiral PIMCs in HPLC chiral separation. A new chiral polyimine macrocycle was designed and synthesized, and then bonded onto thiolated silica gel to prepare chiral stationary phase (CSP) for enantioseparation with excellent enantioselectivity in NP-HPLC and RP-HPLC. [Display omitted] • A new chiral macrocycle was simply synthesized by one-step reaction with high yield. • A novel chiral macrocycle-based CSP was prepared. • Excellent enantioselectivity of the CSP in normal-phase and reversed-phase HPLC. • Good chiral recognition complementarity to Chiralpak AD-H and Chiralcel OD-H columns. • Great potential of chiral polyimine macrocycles for HPLC enantioseparation. [ABSTRACT FROM AUTHOR]

Chiral capillary gas chromatography has been widely applied to separate volatile and thermally stable enantiomers due to its advantages of simplicity, high efficiency, fast analysis, good sensitivity, and absence of liquid mobile phases. In the first part of this article, recent research progress (from 2010 to the present) concerning newly developed chiral stationary phases based on cyclofructan derivatives and chiral porous materials, including metal-organic frameworks, covalent organic frameworks, inorganic mesoporous silicas, and molecular cages for use in gas chromatography, and the synthetic strategies for obtaining chiral porous materials, was reviewed. Finally, we discussed in detail the separation performances and chiral recognition mechanisms of novel chiral recognition materials coated on capillary columns towards various types of enantiomers, namely (1) amino acid derivatives; (2) alcohols, amines, and amino alcohols; (3) organic acids; (4) aldehydes and ketones; (5) ethers and epoxides, and (6) esters and other enantiomers. • Advances on various novel CSPs for GC enantioseparation were reviewed during 2010–2019. • The synthesis strategies to construct chiral porous materials were covered. • The resolution of different types of enantiomers on the novel CSPs was discussed. • The chiral recognition mechanisms between novel CSPs and chiral analytes were explained. • We summarize the advantages and disadvantages of novel CSPs used in GC. [ABSTRACT FROM AUTHOR]

• A chiral porous organic cage based CSP was prepared by thiol-ene click reaction. • Good enantioselectivity of the CSP in both normal-phase and reversed-phase HPLC. • Various racemates have been well enantioseparated on the prepared CSP. • Enantiomers separation scope and applicability of POCs-based HPLC columns have been broadened. • Promising candidate of chiral porous organic cages for HPLC enantioseparation. Porous organic cages (POCs) are a new kind of porous molecular materials, which have gained widespread interest in many fields due to their intriguing properties, including excellent molecular solubility, inherent molecular cavity and rich host-guest chemistry. To date, many chiral POCs have been explored as chiral stationary phases (CSPs) for gas chromatographic (GC) separation of enantiomers. However, the applications of chiral POCs for high performance liquid chromatography (HPLC) enantiomeric separation is extremely rare. In this study, we report the construction of thiol-ene click reaction for the preparation of CSP for HPLC by using a [4+8]-type chiral POC NC4-R as chiral selector. The fabricated CSP showed good chiral resolution performance not only in normal-phase HPLC (NP-HPLC) but also in reversed-phase HPLC (RP-HPLC). Seventeen and ten racemates were well resolved in the two separation modes, respectively, including ketones, esters, alcohols, phenols, amines, ethers, organic acids, and amino acids. Moreover, the fabricated column also shows good chiral recognition complementarity to two popular chiral HPLC columns (Chiralpak AD-H and Chiralcel OD-H columns) and previously reported chiral POC NC1-R-based HPLC column, which can resolve some racemates that unable to be resolved by the two commercially available chiral HPLC columns and NC1-R-based column. The relative standard deviation (RSD) values (n = 4) of retention time and resolution (Rs) of analytes separated on the column were less than 0.3 % and 0.5 % after it was subjected to different injections, showing the good reproducibility and stability of the NC4-R-based column. This work demonstrated high potentials of chiral POCs for HPLC enantioseparation and the applicability of chiral POC-based HPLC columns can be broadened by developing more chiral POCs with diverse structures as chiral selector for HPLC. [ABSTRACT FROM AUTHOR]

Chiral covalent organic frameworks (CCOFs) have potential application in enantioseparation due to their advantages, such as large surface area, abundant chiral recognition sites and good chemical stability in organic solvents. However, the application of CCOFs in high performance liquid chromatography (HPLC) for enantioseparation has been rarely reported because of the shortcomings of CCOFs, such as light weight, irregular shape, and wide particle size distribution. In order to overcome the above shortcomings, a one-pot synthetic method was adopted to prepare a core-shell composite (β-CD-COF@SiO 2) via the growth of chiral β-CD COF on the surface of amino-functionalized SiO 2 microspheres. The as-prepared β-CD-COF@SiO 2 microspheres were used as a stationary phase for HPLC enantioseparation. The resolution ability of the β-CD-COF@SiO 2 -packed column toward various chiral compounds was investigated using n-hexane/isopropanol as the mobile phase. The results show that the chiral β-CD-COF@SiO 2 -packed column exhibited excellent chiral recognition ability for 24 pairs of chiral compounds with good reproducibility. These successful applications indicate that the preparation of the chiral COFs@SiO 2 core-shell microspheres as a novel stationary phase for enantioseparation has good application prospects in HPLC. [Display omitted] • A chiral core-sell β-CD-COF@SiO 2 microspheres composite was prepared using an in-situ growth strategy. • The β-CD-COF@SiO 2 core-shell microspheres as a novel chiral stationary phase was first applied for HPLC enantioseparation. • The packed column exhibited high enantioselectivity and excellent separation performance toward various racemates. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal-organic frameworks (MOFs) have attracted a substantial amount of attention due to special properties, such as gas adsorption, chromatographic separation, and catalytic activity. Herein, a post-modification method was used to modify the surface of achiral MOFs using chiral polyaniline to synthesize a chiral core–shell composite (MIL-101@c-PANI), which was used for the first time as a stationary phase for the separation of chiral compounds. Twelve kinds of chiral compounds, including alcohols, ketones, esters, aldehydes, organic acids and amines were separated on the MIL-101@c-PANI packed column. Moreover, the column also showed good selectivity for the separation of positional isomers. Some chiral compounds that cannot be separated using a commercially available tris(3,5-dimethylphenylcarbamoyl) amylose-packed column (AD column), could be separated on the MIL-101@c-PANI column. The effects of the analyte mass and column temperature on the separation efficiency were investigated. The column exhibited good stability and reproducibility during the enantioseparation of chiral compounds. The MIL-101@c-PANI composite gives rise to a synergistic effect by combining the advantages of c-PANI and MIL-101, which is favorable for an improvement in the chiral separation performance. Therefore, this work shows that such composite materials will be very attractive in the field of separation science. [ABSTRACT FROM AUTHOR]