Chirality最新文献

A vibrational circular dichroism (VCD) instrument having a thermoelectrically cooled detector (denoted as a TEC unit) was constructed in this study. An electronic device, instead of liquid nitrogen, was employed in the instrument to cool the detector. The feasibility of the system was examined by recording the VCD spectra of liquid pinenes and insect wings. VCD signals were obtained at a constant baseline that was stable for more than 40 h. The spectrometer equipped with a TEC unit exhibited potential for performing measurements for prolonged time periods.

Chiral pesticides often undergo enantioselective degradation during food fermentation. In this study, the enantioselective fates of seven chiral pesticides during processing of wine and rice wine were investigated. The results revealed that R-metalaxyl, R-mefentrifluconazole and S-hexaconazole were preferentially degraded during wine processing with EF values of 0.57, 0.78, and 0.43, respectively, whereas S-metalaxyl and R-hexaconazole were preferentially degraded during rice wine processing with EF values of 0.44 and 0.54, respectively. Stereoselectivity was attributed to fermentative bacterial activity. The processing factor (PF) values for the five pesticides ranged from 0.04 to 0.34 during wine processing and from 0.02 to 0.29 during rice wine processing, suggesting that fermentation can mitigate pesticide exposure risks and ensure food safety. This study enhances our understanding of enantioselective fate of chiral pesticides during fermented food processing, provides guidance for the application of chiral pesticides, and enables the dietary risk of chiral pesticides in processed products to be assessed more accurately.

Efficient enantioselective separation is a critical process in pharmaceutical and chemical industries for the production of chiral compounds. Herein, we developed a novel approach for the efficient enantioselective separation of primary amines using supercritical fluid chromatography (SFC) with a commercially available SFC column, Cel1. The key factors of separation, including cosolvent ratios, total cosolvent percentages, and temperature, were systematically assessed in this study. It revealed that utilization of a cosolvent mixture consisting of methanol and isopropanol in a 1:3 (v/v) ratio with a low total cosolvent percentage of 5% resulted in superior retention and selectivity. Additionally, it was observed that maintaining mid-range temperatures at 30 and 35°C achieved optimal balance between retention and efficiency. Employment of commercially available SFC columns streamlined the separation process, reducing analysis time and labor. This study highlights the effectiveness of SFC as a powerful tool for conducting high-throughput enantioselective separations in pharmaceutical and fine chemical industries.

Enantiomeric analysis of chiral drugs is very significant, as their enantiomers display different pharmacological or toxicological behavior towards living systems. Among these drugs, β-blockers are available as racemates, where their enantiomers display different pharmacological effects. Herein, we report enantioselective separation of two β-blockers, namely, atenolol and sotalol, using a derivatization approach. The analytes were derivatized with “(S)-1-[1H-benzo(d)(1,2,3)triazol-1-yl]-2-[6-methoxynaphthalen-2-yl-propan-1-one]” {(S)-BTMNP} in a straightforward derivatization step. The resulting diastereomers were separated on a reverse-phase HPLC C18 column with a mobile phase composed of acetonitrile and TEAP buffer (75:25, v/v, pH = 3.5) and detection at 230 nm. This method achieved successful enantiomer separation for both drugs within 20 min, yielding resolution values greater than 3.8. The detection limits were determined to be 6.4 and 4.6 ng mL⁻¹ for atenolol and sotalol, respectively, which indicated sensitivity and effectiveness of the method for the analysis of two β-blockers from their dosage formulations.

A chiral porous organic polymer (cPOP) was synthesized through nucleophilic substitution polymerization between dichloromaleimide and aromatic amine. This cPOP was used as a new chiral stationary phase (CSP) for gas chromatography (GC) chiral separation. In this work, we first used this cPOP as the CSP for gas chromatography to investigate its ability to separate racemic mixtures, including amino acid derivatives, chiral alcohols, aldehydes, alkanes, ketones, esters, and organic acids. The results showed that the column can effectively separate various racemic mixtures and achieve baseline separation of threonine (Rs = 1.91). Furthermore, the separation mechanism was elucidated by density functional theory (DFT) simulation. Additionally, the cPOP column demonstrated good repeatability and stability. The relative standard deviations (RSDs) for intraday were 0.11%–0.12% (n = 3) for the retention time of n-butyl glycidyl ether, 0.1%–0.34% (n = 3) for interday, and 2.25%–3.37% (n = 3) for column to column. This work shows that cPOP has good potential as chiral stationary phases in gas chromatography.

Magnetic circularly polarized luminescence (MCPL) spectroscopy is widely used to evaluate the luminescence dissymmetry factor (g_MCPL) for compounds. However, even for the same instrument and operating conditions, the measured g_MCPL is affected by errors associated with sources such as baseline drift and spectral noise, and so the range of variation of g_MCPL must be considered when comparing values, which requires multiple measurements for the same sample. Also, because many samples undergo photodegradation under excitation light, it is difficult to accumulate and average spectra for samples with weak MCPL signals to improve the signal-to-noise ratio. Single measurements must therefore be performed on multiple samples and the results averaged. Furthermore, for samples with a small Stokes shift, spectral correction is required to compensate for the intensity reduction due to the inner-filter effect (IFE). Such measurements are generally performed manually and are therefore time consuming and prone to human error. Here, we demonstrate the use of a newly developed high-throughput MCPL system to automatically measure MCPL and fluorescence spectra of multiple samples of phthalocyanine complexes with high efficiency and reduced human errors. This system allows the incorporation of effective countermeasures to the issues of g_MCPL variation, sample photodegradation, extremely weak MCPL signals, and the IFE.

Inclusion complexation, hydrogen bonds, π–π interaction, dipole–dipole interaction, and steric hindrance effect all contribute to the enantioseparation ability of cyclodextrin (CD) or CD derivatives. In this work, one native cationic CD chiral stationary phases (SHCDCSP) and four derivatized CD-CSPs, namely, per(4-trifluoromethyl) phenylcarbamoylated-β-CD CSP (SFPhCDCSP), per(4-chloro) phenylcarbamoylated-β-CD CSP (SCPhCDCSP), per(4-bromo) phenylcarbamoylated-β-CD CSP (SBPhCDCSP), and per(4-methyl) phenylcarbamoylated-β-CD CSP (SMPhCDCSP), were prepared via thioether linkage and applied for the enantioseparation of chiral lactides and chiral diketones in both reverse phase (RP) and normal phase (NP) modes. Most of the studied chiral lactides were found to be well resolved (R_s > 1.5) under RP mode, especially Met-Sty-Ibn (compound 11) is observed to display highest resolutions (R_s = 5.09, R_s = 3.17) among all the analytes on the SFPhCDCSP and SMPhCDCSP. In NP mode, SFPhCDCSP showed excellent chiral recognition ability towards chiral lactides. The comparison study of CD-CSPs reveals the structure of CSPs play a significant role on the enantioselectivities.

Olean is the chiral spiroacetal sex pheromone of the female olive fruit fly Bactrocera oleae. Laboratory tests have demonstrated that the (R)-(−)-olean enantiomer is active on males, whereas females respond to (S)-(+)-olean. Here we present the first HPLC enantioseparation of olean using polysaccharide derivatives as chiral stationary phases and a polarimetric detector equipped with a micro-flow cell capable of detecting optical rotation at six different wavelengths. Unlike blind UV detection, the polarimetric detector allows the chiral spiroacetal, which lacks a chromophore, to be detected as bisegnate peaks, indicating the opposite sign of the optical rotation. The HPLC enantioseparation was optimized on the coated type amylose-based Chiralpak AS-H CSP using a mobile phase consisting of n-hexane-2-propanol 99.99:0.01 (v/v). These conditions were scaled up to a semi-preparative level and allowed resolution of 2.5 mg of racemic sample in 5 min. Multiwavelength optical rotation detection during HPLC enantioseparation of racemic samples provides a direct readout of the stereochemistry of olean and allows tracking of virtual optical rotation dispersion curves without the need for preliminary collection of enantiomeric samples by semi-preparative HPLC.