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Asymmetric Centers, Functional Groups, and Characterization
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
Enantiomers can also be separated using column chromatography equipped with chiral material. The two enantiomers reversibly bind to the chiral material at different rates, thereby enabling their separation. Enantiomers with dramatic pharmacological activity differences often require that they are separated before being marketed. It is important to note that separation of enantiomers can be tedious and expensive, and some drugs are still marketed as racemic mixtures.
Stereochemistry
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Enantiomers are defined as stereoisomers that have non-superimposable mirror images. When a mirror is held up to a molecule possessing a stereogenic center, its mirror image is observed. If one tries to superimpose (match every atom in both molecules by laying one on the other), a chiral molecule and its mirror image are not superimposable. They are, therefore, different molecules. A more precise definition is that two stereoisomers that are non-superimposable mirror images are enantiomers. It is important to understand that recognizing enantiomers as stereoisomers is an important part of the definition. How can enantiomers of 2-chlorobutane be compared?
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Published in Luis Liz-Marzán, Colloidal Synthesis of Plasmonic Nanometals, 2020
Jatish Kumar, Luis M. Liz-Marzán
Chirality is a fundamental property associated with the symmetry of molecules, but also of nanoparticles and macroscopic objects. In terms of symmetry elements, a chiral object does not possess inversion symmetry or mirror planes. Hence, an object is termed chiral if it cannot be superimposed on its mirror image by simple rotations or translations. Each of such non-superimposable mirror images in molecular systems is known as an enantiomer. Enantiomeric forms generally display similar physical properties and are thus difficult to differentiate. The chiral nature of molecules becomes evident by analyzing their response to polarized light, or when they interact with another chiral molecule.
Supervisory system for automated simulated moving bed (SMB) liquid chromatography (LC)
Published in Instrumentation Science & Technology, 2023
R. C. de Holanda, F. C. Cunha, A. R. Secchi, A. G. Barreto
Racemic mixtures are solutions composed of two molecules with the same formula, one being the mirror image of the other. Therefore they cannot be overlapped. These molecules are known as enantiomers.[1] Different racemic mixtures are produced daily in many branches of the economy, from food processing to the pharmaceutical industry.[2] One example is praziquantel (PZQ), a drug prescribed to treat Schistosomiasis disease. Only the (R)-PZQ has proven pharmacological activity against the disease, while the (S)-PZQ provides a significant bitterness to the drug, causing vomiting.[3] In the recent decades, many investments in research and development have been made targeting the creation of new technologies capable of producing a drug with high purity of (R)-PZQ to increase the production efficiency.[4]
Optimization of asymmetric bioreduction conditions of 1-(thiophen-2-yl)ethanone by Weissella cibaria N9 using a desirability function-embedded face-centered optimization model
Published in Preparative Biochemistry & Biotechnology, 2023
Mohammed Bolubaid, Akın Özdemir, Enes Dertli, Mohammed Alamoudi, Osman Taylan, Derviş Karaboğa, Mustafa Tahsin Yılmaz, Engin Şahin
Living organisms include enantiomerically pure biological molecules. Chiral compounds interact chirally with receptors, and each receptor treats each enantiomer differently. Thus, each enantiomer possesses different biological properties.[1] The asymmetric reduction has become a significant process for prochiral ketones in organic chemistry and the pharmaceutical industry.[2,3] Because of their diverse biological activity as food additives, fine chemicals, primary pharmacological intermediates, and secondary alcohols have attracted interest.[4,5] An essential family of compounds known as chiral seconder alcohols, such as precursor molecules, may be employed to create enantiomerically pure medicinal ingredients. Because chiral secondary alcohols are so crucial, it is necessary to find novel techniques to produce them in greater numbers and more efficiently. Enantiopure chiral secondary alcohols may be created using chiral ligands; however, doing so costs money and results in harmful byproducts.[6–9]
Pair and mediated RET between two chiral molecules
Published in Molecular Physics, 2022
Characteristic of a pair of enantiomers is the non-superposability of their mirror-image structures.Molecules possessing this property are classified as chiral and assume left- and right-handed forms. They exhibit a number of well-known linear and nonlinear chiroptical effects such as optical rotation, circular dichroism and circularly polarised luminescence, differential scattering of circularly polarised radiation, sum/difference frequency and second- and third-harmonic generation of light [1–6]. Discriminatory phenomena are not only limited to spectroscopic processes but also manifest in coupling between optically active molecules such as in electrostatic and contact types of interactions [7]. A ubiquitous example is the dependence of the van der Waals dispersion force between two chiral molecules on their relative handedness [8–13]. Replacing one enantiomer of the pair by its antipodal form changes the sign of the energy shift. A similar feature is found in the radiation-induced dispersion interaction between two optically active molecules [14,15], a process more generally known as ‘optical binding’.