As the understanding of the various biological actions of compounds with different stereochemistry has grown, the necessity to develop methods for the analytical qualification and quantification of chiral products has become particularly important. The last quarter of the century has seen a vast growth of diverse chiral technologies, including stereocontrolled synthesis and enantioselective separation and analysis concepts. By the introduction of covalently bonded silica-based chiral stationary phases (CSPs), the so-called direct liquid chromatographic (LC) methods of enantiomer separation became the state-of-the-art methodology. Although a large number of CSPs is available nowadays, the design and development of new chiral selectors and CSPs are still needed since it is obvious that in practice one needs a good portfolio of different CSPs and focused "chiral columns" to tackle the challenging tasks. This review discusses and summarizes direct enantiomer separations of chiral acids and ampholytes applying anionic and zwitterionic ion-exchangers derived from Cinchona alkaloids with emphasis on literature data published in the last 10 years. Our aim is to provide an overview of practical solutions, while focusing on the integration of molecular recognition and methodological variables.

Chirality lies at the heart of chemistry, governing the structure-function relationships of biomolecules, pharmaceuticals, and catalysts. However, rapid and label-free enantioselective analysis remains an enduring challenge due to the intrinsic similarity of enantiomers' physicochemical properties. Here, we report a contact electrification-based triboelectric sensing platform for the enantioselective recognition of chiral amino acids, achieved by coating CuO nanowires. The approach exploits chirality-dependent interfacial electron transfer, whereby differences in molecular orbital alignment and work function between enantiomers generate distinct electronic signatures during controlled contact-separation with acetone. Kelvin probe force microscopy, ultraviolet photoelectron spectroscopy, and density functional theory calculations reveal that subtle differences in side-chain geometry modulate nanoscale surface potentials and electron cloud overlap, leading to quantifiable shifts in charge transfer efficiency. The method achieves millisecond-scale discrimination across charged, polar uncharged, and sulfur-containing amino acids, with orthogonal evidence from molecule specific enantioselective contact-electrocatalytic degradation of methyl orange. By transducing stereochemical information directly into measurable electrical outputs, this work demonstrates a mechanistically grounded chemical sensing paradigm, offering a versatile platform for pharmaceutical quality control and biomolecular diagnostics.

With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug enantiomers is caused by differential enantiospecific binding to receptors. This review is devoted to the specific recognition and resolution of chiral molecules by chromatography and membrane-based enantioseparation techniques. Chromatographic enantiomer separations with chiral stationary phase (CSP)-based columns and membrane-based enantiomer filtration are detailed. In addition, the unique properties of these chiral resolution methods have been summarized for practical applications in the chemistry, environment, biology, medicine, and food industries. We further discussed the recognition mechanism in analytical enantioseparations and analyzed recent developments and future prospects of chromatographic and membrane-based enantioseparations.

Enantioselective drug analysis: problems and resolutions. 1. With the increasing appreciation that the enantiomers of a chiral drug can differ pharmacokinetically and/or pharmacodynamically, there is considerable interest in methods for the resolution and quantification of enantiomers. 2. Enantiomers possess identical physical and chemical properties in a symmetrical environment and, therefore, their resolution requires the introduction of an asymmetric or chiral environment allowing diastereomeric interactions. This can be achieved using a number of chromatographic techniques, of which the most developed and widely used is high-performance liquid chromatography (HPLC). 3. Resolution and quantification of enantiomers can be performed using HPLC by either converting the enantiomers to covalent diastereomers prior to chromatography or introducing a chiral environment to the chromatographic system, thereby allowing temporary diastereomeric interactions. 4. Antibodies are chiral molecules which can bind the enantiomers of a chiral drug in a differential manner.

1. With the increasing appreciation that the enantiomers of a chiral drug can differ pharmacokinetically and/or pharmacodynamically, there is considerable interest in methods for the resolution and quantification of enantiomers. 2. Enantiomers possess identical physical and chemical properties in a symmetrical environment and, therefore, their resolution requires the introduction of an asymmetric or chiral environment allowing diastereomeric interactions. This can be achieved using a number of chromatographic techniques, of which the most developed and widely used is high-performance liquid chromatography (HPLC). 3. Resolution and quantification of enantiomers can be performed using HPLC by either converting the enantiomers to covalent diastereomers prior to chromatography or introducing a chiral environment to the chromatographic system, thereby allowing temporary diastereomeric interactions. 4. Antibodies are chiral molecules which can bind the enantiomers of a chiral drug in a differential manner. This is the basis of enantioselective immunoassay, which is a promising technique for the enantioselective analysis of drugs in biological fluids. 5. Each of the methods available has its limitations, advantages and potential applications in the pharmaceutical industry.

Chiral mesoporous silica nanostructures (MSNs) have emerged as a cutting-edge material in nanotechnology. These nanostructures not only retain the tunable physicochemical properties of traditional MSNs-such as adjustable pore size, high surface area, and excellent biocompatibility-but also exhibit unique functionalities and biological behaviors due to their helical architectures at both molecular and macroscopic levels. This inherent chirality grants chiral MSNs exceptional potential in diverse applications, including chiral catalysis, enantiomeric separation, chiral recognition, and advanced drug delivery systems. Over the past five years, substantial progress has been made in understanding their synthesis mechanisms and practical applications. This review provides a comprehensive analysis of recent advancements in chiral silica nanostructures, with a focus on the synthesis strategies and applications of chiral MSNs. Emphasis is placed on their roles in chiral recognition, drug delivery, chiral separation, nanomedicine, and asymmetric catalysis. By highlighting these developments, this review serves as a roadmap for the rational design and translational applications of chiral silica nanostructures, offering valuable guidance for unlocking their full potential.

Diastereomer Diastereomers (also called diastereoisomers) are stereoisomers which are not enantiomers. They are molecules which have the same atoms and bonds but different stereochemistry in at least one, but not all, of their chiral centres. Diastereomers can have very different properties even though they look similar.[1] This is different from enantiomers, that have exactly the same properties except when in a chiral environment like the human body. Every chiral centre in a molecule has two possible ways of putting the groups in space. With only one chiral centre, there are two enantiomers. With two chiral centres, you can form 4 different isomers. When all chiral centres are changed at the same time, two pairs of enantiomers are formed. When only one chiral centre is changed at a time, sets of diastereoisomers are formed. With more chiral centres the possibilities are many more. Diastereoisomers which are different at only one of more chiral centres are called epimers. For example, D-Threose and D-Erythrose (see picture) are diastereomers because they are different at only one of two chiral centres.

A single drop of a natural chiral ionic liquid (NCIL) serves as a wireless electrochemical microreactor for enantioselective synthesis. This system yields high selectivity (>90% ee) and demonstrates dynamic stereocontrol, where the enantiomeric excess is directly modulated by the external electric field. This catalyst-free strategy introduces a new paradigm for sustainable, tunable asymmetric reactions.

In general molecules that rotate light in differen directions are called optical isomers. - Dextrorotatory (+ enantiomer) – rotates the plane polarized light clockwise (when viewing towards the light source) - Levorotatory (- enantiomer) – rotates the plane polarized light counterclockwise Circular Dichroism Another property of chiral molecules is called circular dichroism (CD). This pertains to their differential absorption of left and right circularly polarized light. When left and right circularly polarized light passes through chiral molecules, the absorption coefficients differ so that the change in absorption coefficients does not equal zero. where ΔA is the difference between absorbance of left circularly polarized (LCP) and right circularly polarized (RCP) light (this is what is usually measured). Where [J] = molar concentration of the sample and l is the path length. The CD signals of chiral molecules can give important information and this information can be used for visible and ultraviolet spectroscopy. Every chiral molecule shows a particular CD spectrum.

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