ABSTRACT Chiral high‐performance liquid chromatography (HPLC) is commonly used for the separation of enantiomeric compounds. We assessed the performance of 22 chiral HPLC columns from various manufacturers to determine their efficiency in separating enantiomers. A total of 30 racemic analytes (comprising acidic, neutral, and basic compounds) were analyzed using a gradient strategy of 80%–20% aqueous over 20 min. The columns were ranked based on the number of analytes they were able to separate, the resolution achieved for each enantiomer pair separation, and a combination of both parameters for each of the compound groups. The columns that achieved the highest number of enantiomer separations were the Lux i‐Amylose‐3 for acidic compounds and the MAC‐MOD Chiral Amy‐6 for neutral and basic compounds with the MAC‐MOD Chiral Amy‐6 being the column with the most enantiomers separated. The column that achieved higher resolution separations was the MAC‐MOD Chiral Amy‐6 for all types of compounds. When considering both parameters, the highest ranking columns were the Lux i‐Amylose‐3 and the MAC‐MOD Chiral Amy‐6 for acidic compounds and the MAC‐MOD Chiral Amy‐6 for neutral and basic compounds with the MAC‐MOD Chiral Amy‐6 being the highest ranked overall. Following data collection and analysis, a hierarchical list was created based on the highest probability of success for future screenings.
ABSTRACT A novel π‐conjugated chiral system, BT 2 T 4 –(CH 2 OH) 2 , derived from the atropisomeric scaffold 2,2′‐bis[2‐(5,2′‐bithienyl)]‐3,3′‐bithianaphthene ( BT 2 T 4 ), was synthesized to provide terminal hydroxymethyl groups for further functionalization. Baseline enantioseparation was achieved by high‐performance liquid chromatography using the immobilized polysaccharide‐derived Chiralpak IB chiral stationary phase under medium‐polarity mobile‐phase conditions, which ensured adequate analyte solubility while maintaining excellent chiral recognition. The optimized protocol allowed the isolation of the individual enantiomers in high enantiomeric purity (ee > 99%). The absolute configuration of the separated enantiomers was assigned through a direct correlation between on‐line CD detection and CD spectra, providing a reliable stereochemical readout. Under specific synthetic conditions, additional minor species were detected; however, their formation was found to depend on reaction and handling parameters, such as the solvent, and can be minimized by conducting both the synthesis and storage in dichloromethane. Overall, BT 2 T 4 –(CH 2 OH) 2 represents a chiral π‐conjugated platform that offers potential applications in enantioselective recognition and in the development of chiroptical and sensing materials.
ABSTRACT Colloidal nanostructures capable of generating circularly polarized light emission (CPLE) are of importance for probing nanoscale chiral light‐matter interactions and for developing solution‐processable photonic materials. However, simultaneously achieving efficient emission and pronounced polarization asymmetry within a colloidal system remains challenging. Here, we report compact and dispersible HgS@SiO 2 ‐FAPbX 3 colloidal nanocolloids formed by depositing achiral formamidinium lead‐halide perovskites (FAPbX 3 , X = Br, Cl/Br, or Br/I) onto silica‐coated twisted bipyramidal α‐HgS nanoparticles. The resulting particles exhibit CPLE at 481 to 533 and 574 nm, spanning the blue, green, and yellow spectral regions. Reversing the HgS morphology from left‐ to right‐twisted reverses the CPLE sign. The observed CPLE arises from post‐emission chiroptical modulation of perovskite photoluminescence through interaction with the twisted HgS nanostructures. By integrating wavelength‐tunable emission and polarization regulation within discrete, dispersible nanoparticles, these composite nanocolloids provide solution‐processable nanoscale building blocks for CPLE‐active materials and higher‐order chiral photonic assemblies.
This work provides a unified theoretical framework for analyzing chiroptical properties, specifically circular dichroism and circular birefringence, using Mueller matrix polarimetry. We consolidate previously derived results into a comprehensive and practical guide, presenting explicit closed‐form expressions for the most general nondepolarizing Mueller matrix and its key limiting cases. The analysis covers the general scenario involving six independent polarization parameters, approximations for weak effects, and important special cases such as systems with coincident linear axes, pure linear or circular anisotropy, and nonabsorbing or nonretarding media. The matrices provided here are intended to facilitate the design, analysis, and interpretation of polarimetric experiments in chemistry, biology, and materials science.
This research aims to investigate the stereoselective permeation differences and molecular recognition mechanisms of ketoprofen enantiomers in the chiral microenvironment of the stratum corneum (SC). This also aims to provide theoretical support for developing highly efficient and precise single-enantiomer transdermal drug delivery systems. The permeation behaviors of dexketoprofen and its racemate through excised full-thickness rat skin in three different solvent systems were studied using Franz diffusion cells. The solubility, apparent partition coefficients, and differential scanning calorimetry were used to assess the physicochemical and thermodynamic properties of both forms. Fourier transform infrared (FTIR), 13C NMR, attenuated total reflection-FTIR (ATR-FTIR), and Raman spectroscopic techniques were extensively performed to investigate micro-interactions between drug and core SC (ceramide NP and keratin) components. In addition, in order to affirm the mechanisms, binding energy, cohesive energy density, and the radial distribution function along with mean square displacement were evaluated using molecular docking and molecular dynamics simulations. Based on in vitro permeation results, the cumulative permeated amounts of dexketoprofen in all three solvent systems were significantly higher than those of racemic ketoprofen (approximately 1.2-fold). Characterizations by thermodynamic and physicochemical methods showed that dexketoprofen displayed a relatively low melting point (76.26 degrees C), enthalpy of fusion (26.39 kJ/mol), lattice energy, and higher lipophilicity and solubility, which gave rise to a greater thermodynamic driving force for drug release. Both spectroscopic analyses and molecular simulations confirmed that dexketoprofen formed a stronger intermolecular hydrogen bonding network with ceramide NP (binding energy: -21.63 kcal/mol). This robust spatial affinity remarkably perturbed the tightly ordered arrangement of the SC lipid bilayer, which may induce a decrease in lipid orderliness and substantially increase the fluidity. The transdermal superiority of dexketoprofen within the chiral skin barrier is synergistically attributed to its high thermodynamic activity, driven by a lower lattice energy, and its stronger microscopic stereoselective interactions with SC components. This study systematically elucidates the stereoselective mechanisms underlying the transdermal permeation of chiral drugs, thereby providing a scientific basis for the development of transdermal formulations containing a single enantiomer.
