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A homochiral metal-organic framework, [Ni(D-L)(py)2(H2O)2]n (1) [D-H2L = 4,4′-[[(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarbonyl]bis-(azanediyl)]dibenzoic acid], has been successfully synthesized based on D-camphorate-derived enantiopure ligand. 1 was characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Fourier transform infrared spectral analysis (FTIR), thermogravimetric analysis (TGA) and the circular dichroism (CD) spectrum. The experimental results show that 1 features a homochiral triple helix and is formed a 3D supramolecular framework by supramolecular interactions. In addition, the circular dichroism (CD) spectrum verifies the chirality introduction from the ligand to crystal. The successful preparation of the homochiral Ni-MOF provides more possibilities of employing the chiral ligand to produce various chiral MOFs. [ABSTRACT FROM AUTHOR]

Homochiral metal-organic frameworks (MOFs) have attracted considerable attention in many fields of research, such as chiral catalysis and chiral chromatography. However, only few homochiral MOFs can be effectively used in capillary electrochromatography (CEC) and their performances are far from adequate. In this study, we successfully synthesized achiral nanocrystalline MIL-53. A facile post-synthetic modification strategy was then implemented to functionalize the product, yielding a homochiral MOF: l-His-NH-MIL-53. This MOF was then employed as a chiral coating in open-tubular CEC mode (OT-CEC), and, as such, it exhibited high enantioselectivities for several racemic drugs. The homochiral MOF and the fabricated capillary coating were systematically characterized using transmission electron microscopy, scanning electron microscopy (with energy-dispersive X-ray spectrometry), Fourier-transform infrared spectroscopy, X-ray diffractometry, thermogravimetric analysis, circular dichroism spectroscopy, Brunauer-Emmett-Teller surface area measurements, and X-ray photoelectron spectroscopy. This study is expected to provide a new strategy for the design and establishment of MOF-based chiral OT-CEC systems.

Homochiral metal-organic frameworks (MOFs) have attracted considerable attention in many fields of research, such as chiral catalysis and chiral chromatography. However, only few homochiral MOFs can be effectively used in capillary electrochromatography (CEC) and their performances are far from adequate. In this study, we successfully synthesized achiral nanocrystalline MIL-53. A facile post-synthetic modification strategy was then implemented to functionalize the product, yielding a homochiral MOF: l -His-NH-MIL-53. This MOF was then employed as a chiral coating in open-tubular CEC mode (OT-CEC), and, as such, it exhibited high enantioselectivities for several racemic drugs. The homochiral MOF and the fabricated capillary coating were systematically characterized using transmission electron microscopy, scanning electron microscopy (with energy-dispersive X-ray spectrometry), Fourier-transform infrared spectroscopy, X-ray diffractometry, thermogravimetric analysis, circular dichroism spectroscopy, Brunauer-Emmett-Teller surface area measurements, and X-ray photoelectron spectroscopy. This study is expected to provide a new strategy for the design and establishment of MOF-based chiral OT-CEC systems. [Display omitted] • l -His-NH-MIL-53 was prepared as a novel chiral stationary phase for OT-CEC. • Multiple methods were employed to characterize the MOF and MOF coating. • MOF-modified capillary exhibited high enantioselectivity for several racemic drugs. [ABSTRACT FROM AUTHOR]

The development of a highly selective and sensitive optical method for quantitative enantioselective sensing of chiral amino acids in the presence of other amino acid interferences has remained a major challenge to date. Herein, a homochiral metal–organic framework (MOF), [Zn(L)(2,2′‐bipy)]·H2O (LNNU‐1) (H2L = HOOCC6H4CH2PO(OH)(OC2H5), 2,2′‐bipy = 2,2′‐bipyridine), is designed to interact with tryptophan via multiple noncovalent interactions. The interactions result in the emergence of a strong induced circular dichroism signal. This enables accurate determination of the absolute configuration and enantiomeric ratio of chiral tryptophan in water, mixed natural amino acids, and blood plasma components without any interference from other coexistent species. A simple device with advantageous characteristics of reusability and simple manipulation is designed for enantioselective sensing assay. The obtained results suggest that the rationally designed homochiral MOF is a promising candidate for enantioselective sensing of chiral species. [ABSTRACT FROM AUTHOR]

Less attention has been paid to the solvent-dependent chirality transformation behavior of coordination compounds when using achiral precursors. We have successfully prepared one known helical achiral compound ( α -[AgL] n ∙ n H 2 O, 1 ) using water or DMSO as a solvent, one new helical homochiral MOF ( β -[AgL] n ∙ n H 2 O, 2 ) using DMF, dimethyl acetamide or ethanol as a solvent, and one new non-helical achiral compound ([Ag 2 L(NO 3 )] n , 3 ) using n -propyl alchohol or cyclohexanol as a solvent, with the V-shaped achiral ligand 3-aminobenzoic acid (HL) as a ligand. Achiral 1 can be converted from chiral isomeric 2 through recrystallization in water. Such successive chirality transformation (achirality → chirality → achirality) behavior is probably proportional the polarity of the used solvent: cyclohexanol ( 3 ) < n -propyl alchohol ( 3 ) < ethanol ( 2 ) < dimethyl acetamide ( 2 ) < DMF ( 2 ) < DMSO ( 1 ) < water ( 1 ). A preliminary study revealed that the isomeric compounds 1 and 2 displayed significantly different photoluminescence. [ABSTRACT FROM AUTHOR]

Here, we present a new family of hierarchical porous hybrid materials as an innovative tool for ultrasensitive and selective sensing of enantiomeric drugs in complex biosamples via chiral surface-enhanced Raman spectroscopy (SERS). Hierarchical porous hybrid films were prepared by the combination of mesoporous plasmonic Au films and microporous homochiral metal-organic frameworks (HMOFs). The proposed hierarchical porous substrates enable extremely low limit of detection values (10−12 M) for pseudoephedrine in undiluted blood plasma due to dual enhancement mechanisms (physical enhancement by the mesoporous Au nanostructures and chemical enhancement by HMOF), chemical recognition by HMOF, and a discriminant function for bio-samples containing large biomolecules, such as blood components. We demonstrate the effect of each component (mesoporous Au and microporous AlaZnCl (HMOF)) on the analytical performance for sensing. The growth of AlaZnCl leads to an increase in the SERS signal (by around 17 times), while the use of mesoporous Au leads to an increase in the signal (by up to 40%). In the presence of a complex biomatrix (blood serum or plasma), the hybrid hierarchical porous substrate provides control over the transport of the molecules inside the pores and prevents blood protein infiltration, provoking competition with existing plasmonic materials at the limit of detection and enantioselectivity in the presence of a multicomponent biomatrix. • Porous SERS senor discriminates chiral drug in the complex biomatrix. • Hierarchical porous sensor consists of mesoporous gold film and nanoporous chiral MOF. • Sensor distinguish two pseudoephedrine (PE) enantiomers with high enantioselectivity and sensitivity. • Sensor provide 10−12 M LOD for PE in undiluted blood plasma. • Chiral MOF layer provide additional chemical SERS enhancement with chemical recognition and discriminant function. [ABSTRACT FROM AUTHOR]