Homometric structures refer to a concept in geometry and topology that pertains to the idea that two or more shapes can have the same or indistinguishable measurements, such as lengths or angles, despite being different in form or arrangement. In other words, two structures are considered homometric if they can be transformed into one another through a series of isometries (like rotation, translation, or reflection) while maintaining the same metric properties.
An immobilized enzyme is an enzyme that has been attached or fixed to a solid support or substrate, which restricts its mobility. This immobilization can enhance the stability, reusability, and control of the enzyme's activity in various applications, such as biocatalysis, pharmaceuticals, and food processing.
Inherent chirality refers to a property of certain molecular structures that possess a chiral center or centers within their configuration, imparting a characteristic that makes them non-superimposable on their mirror images. This type of chirality is fundamentally tied to the arrangement of atoms and the topology of the molecule, which can lead to distinct spatial arrangements of substituents around a chiral center.
Kinetic resolution is a process used in chemistry to separate and purify enantiomers, which are molecules that are non-superimposable mirror images of each other. This technique exploits the difference in reaction rates of enantiomers when they are subjected to a chiral environment, such as a chiral catalyst or reagent.
The Klyne–Prelog system, also known as the Klyne–Prelog priority rules, is a method for specifying and designating the absolute configuration of chiral molecules, particularly in stereochemistry. This system is often used to assign the configuration of stereocenters in organic compounds, particularly for molecules with multiple stereogenic centers.
Kryptoracemic compounds refer to a specific type of stereoisomeric mixture that contains both enantiomers of a chiral compound, but in a way that deviates from the usual racemic mixtures where the two enantiomers are present in equal amounts. The term "kryptoracemic" is used to describe cases where the enantiomers are present in unequal amounts, yet display some degree of symmetry in their spatial arrangement.
The Le Bel–Van 't Hoff rule, also known as the Le Bel-Van 't Hoff rule of stereochemistry, relates to the spatial arrangement of molecules and their optical activity. Specifically, it provides insight into the relationship between the number of stereocenters in a molecule and the number of possible stereoisomers.
The ligand cone angle is a concept used in coordination chemistry to describe the spatial orientation of ligands around a central metal ion in a coordination complex. It refers to the geometric representation of how ligands are arranged and the degree to which they can approach and interact with the central metal atom.
A meso compound is a type of stereoisomer that has multiple stereocenters but is achiral due to an internal plane of symmetry. This means that even though it has chiral centers, the overall molecule is not optically active because one half is a mirror image of the other. Meso compounds typically have symmetrical structures, and this symmetry leads to their achirality.
Molecular configuration refers to the three-dimensional arrangement of atoms within a molecule, particularly how these atoms are bonded together and oriented in space. This includes aspects such as: 1. **Bond Lengths**: The distances between the nuclei of bonded atoms. 2. **Bond Angles**: The angles formed between adjacent bonds at a particular atom. 3. **Dihedral Angles**: The angles between two plane sections formed by four atoms in a molecule.
Mosher's acid, also known as (S)-(+)-2-methyl-2-(trifluoromethyl)benzoic acid, is a chiral auxiliary used in asymmetric synthesis. It is particularly useful for the resolution of enantiomers and for studying stereochemistry due to its ability to form stable complexes with chiral compounds.
Mutarotation is a phenomenon observed in solutions of certain carbohydrates, primarily reducing sugars, where the optical rotation of the solution changes over time until it reaches a stable equilibrium. This change in optical rotation occurs due to the interconversion between different anomeric forms of the sugar, particularly in the case of aldoses and ketoses. In aqueous solution, many aldoses can exist in two cyclic forms (anomers): the alpha (α) and beta (β) forms.
The Natta projection is a stereochemical representation used to depict the three-dimensional arrangement of atoms in a polymer's repeating unit, particularly in the context of polymer chemistry where stereochemistry plays a significant role. Specifically, it is often associated with the structure of isotactic polypropylene, which is a type of polypropylene where all the methyl groups (–CH3) are arranged on the same side of the polymer chain.
A Newman projection is a way of visualizing the three-dimensional (3D) structure of organic molecules, particularly alkanes, in a two-dimensional (2D) format. It allows chemists to analyze the spatial arrangement of atoms and bonds around a specific bond between two carbon atoms. In a Newman projection, one looks straight down the axis of a particular bond (usually a carbon-carbon bond).
Noyori asymmetric hydrogenation is a chemical reaction developed by Japanese chemist Ryoji Noyori, which allows for the selective hydrogenation of prochiral ketones and other similar compounds to produce enantiomerically enriched alcohols. This reaction is particularly significant in the field of asymmetric synthesis, where the goal is to produce one specific enantiomer of a chiral product over the other.
Optical rotation, also known as optical activity, is the phenomenon where the plane of polarized light is rotated when it passes through certain substances. This effect is observed when light interacts with chiral molecules — that is, molecules that cannot be superimposed on their mirror images, similar to how left and right hands are different.
Optical rotatory dispersion (ORD) is a phenomenon in which the optical rotation of a chiral substance varies with the wavelength of light. When plane-polarized light passes through a chiral medium, the plane of polarization is rotated by an amount that depends on the wavelength of the light. This effect is a consequence of the interaction between the light and the chiral molecules in the substance.
P-Chiral phosphines are a class of chiral ligands that are characterized by the presence of a phosphorus atom that is stereogenic (chiral). This means that the phosphorus center can exist in two non-superimposable mirror image forms, leading to different spatial arrangements of substituents attached to the phosphorus atom. In the context of coordination chemistry and catalysis, P-chiral phosphines are particularly valuable because they can impart stereochemical information to reactions, thereby enabling asymmetric synthesis.
Pentane interference typically refers to the impact that pentane, a straight-chain hydrocarbon with five carbon atoms, can have on various chemical analyses, particularly in chromatographic methods. In the context of gas chromatography or mass spectrometry, pentane can co-elute with other compounds, potentially leading to inaccurate results or difficulties in identifying and quantifying other analytes.
The Pfeiffer effect refers to an optical phenomenon observed in certain types of materials when they are subjected to mechanical stress. Specifically, it is related to the anisotropic optical properties of certain crystals, particularly in mineralogy and materials science. When a crystal is deformed or stressed, the optical properties—such as birefringence—can change, leading to variations in the light transmission characteristics of the material.