Metal–Organic Framework [Cd(LTP) ₂ ] _n for Improved Enantioseparations on a Chiral Cyclodextrin Stationary Phase in GC

Abstract

Metal-organic frameworks (MOFs) are a class of novel porous materials consisting of clusters or chains of metal ions and organic linkers. The chiral MOF [Cd(LTP)] (LTP = l(-)-thiazolidine-4-carboxylic acid) possesses infinite extension three-dimensional supramolecular reticular structure with right-handed helix. In this work, three capillary columns (A, B and C) containing MOF [Cd(LTP)], permethylated β-cyclodextrin (CD) and sodium chloride, and MOF [Cd(LTP)] and permethylated β-CD, respectively, have been prepared and their respective enantioseparation abilities have been investigated. The polarities of all of the MOFs and permethylated β-CDs are moderate. The numbers of theoretical plates (plate m) of the three columns have been measured using n-dodecane at 120°C, which followed an increasing order of A (3100) < B (3800) < C (4300). Some racemates were separated with different resolutions on Columns A, B and C. The results indicated that the incorporated MOF [Cd(LTP)] enhanced the separations of racemates on a permethylated β-CD stationary phase with high column efficiency and good reproducibility in gas chromatography.

Structural Transformations of Amino-Acid-Based Polymers: Syntheses and Structural Characterization

“…The thio and amino functional groups of the tpro − ligand can also participate in hydrogen bonding interactions, thus increasing the dimensions of the target products. However, such tpro-based complexes are still rare as of this writing [56,57,58,59]. A chiral l -thioproline species was employed as a ligand to react with the Zn(II) ions under mild conditions, in order to permit some labile compounds with coordinated water molecules to be produced.…”

Metal–organic frameworks in chiral separation of pharmaceuticals

“…The results indicated that the incorporated MOF [Cd (LTP) 2 ] n improved the separations of 14 racemates: (±)-limonene, (±)-1-cyclohexyl amine, (±)-menthol, (±)-dihydrocarvyl acetate, (±)-2-hexanol, (±)-citronellal, (±)-1 phenylethylamine, (±)-rose oxide, (±)-2-amino-1-butanol, (±)-1-phenylethanol, (±)-2-phenyl-1-propanol, (±)-2-methyl-1-butanol, DL-alanine, and DL-arginine, on a permethylated β-CD stationary phase with good efficiency and reproducibility in gas chromatography. 149 A mixedmatrix membrane (MMMs) made of CD-MOF as a chiral selector and polyethersulfone as a matrix elucidated nearly 100% enantioselectivity of R-(+)-1-phenylethanol over S-(À)-1-phenylethanol with n-hexane, whereas the membrane enantioselectivity decreased with the permeation time in the case of methanol and ethanol. 143 The MMM showed a high permeation rate for R-(+)-1-phenylethanol, whereas, in a flux versus time graph, the flux approached zero when a nonpolar solvent n-hexane was used.…”

Single-Crystal to Single-Crystal Structural Transformations of Amino-Acid-Based Coordination Polymers: Syntheses and Structural Characterization

“…The thio and amino functional groups of the tpro  ligand can participate in hydrogen bonding interactions to increase the dimensions of the target products. However, such tpro-based complexes were still rare as of this writing [56][57][58][59]. A chiral L-thioproline species was employed as a ligand to react with the Zn(II) ions under the mild conditions, so that it would permit some labile compounds with coordinated water molecules to be obtained.…”