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Denticity
In coordination chemistry, denticity () refers to the number of donor groups in a given ligand that bind to the central metal atom in a coordination complex. In many cases, only one atom in the ligand binds to the metal, so the denticity equals one, and the ligand is said to be unidentate or monodentate. Ligands with more than one bonded atom are called multidentate or polydentate. The denticity of a ligand is described with the Greek letter κ ('kappa'). For example, κ6-EDTA describes an EDTA ligand that coordinates through 6 non-contiguous atoms. Denticity is different from hapticity because hapticity refers exclusively to ligands where the coordinating atoms are contiguous. In these cases the η ('eta') notation is used. Bridging ligands use the μ ('mu') notation. Classes Polydentate ligands are chelating agents and classified by their denticity. Some atoms cannot form the maximum possible number of bonds a ligand could make. In that case one or more binding si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis acids and bases, Lewis bases. The nature of metal–ligand bonding can range from covalent bond, covalent to ionic bond, ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acids and bases, Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity (chemistry), reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelating Agents
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity. The word ''chelation'' is derived from Greek χηλή, ''chēlē'', meaning "claw"; the ligands lie around the central atom like the claws of a crab. The term ''chelate'' () was first applied in 1920 by Sir Gilbert T. Morgan and H. D. K. Drew, who stated: "The adjective chelate, derived from the great claw or ''chele'' (Greek) of the crab or other crustaceans, is suggested for the caliperlike groups which function as two associating units and fasten to the central atom so as to produce heterocyclic rings." Chelation is useful in applications such as providing nutritional supplements, in chela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxaliplatin
Oxaliplatin, sold under the brand name Eloxatin among others, is a cancer medication (platinum-based antineoplastic class) used to treat colorectal cancer. It is given by intravenous, infusion into a vein. Common side effects include paresthesia, numbness, feeling tired, nausea, diarrhea, and cytopenia, low blood cell counts. Other serious side effects include allergic reactions. Use in pregnancy is known to harm the baby. Oxaliplatin is in the platinum-based antineoplastic family of medications. It is believed to work by blocking the duplication of DNA. Oxaliplatin was patented in 1976 in Japan and approved for medical use in 1996 in Europe. It is on the 2023 WHO Model List of Essential Medicines, World Health Organization's List of Essential Medicines. Medical uses Oxaliplatin is used for treatment of colorectal cancer, typically along with folinic acid (leucovorin) and fluorouracil in a combination known as FOLFOX or along with capecitabine in a combination known as CA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terpyridine
Terpyridine (2,2';6',2"-terpyridine, often abbreviated to Terpy or Tpy) is a heterocyclic compound derived from pyridine. It is a white solid that is soluble in most organic solvents. The compound is mainly used as a ligand in coordination chemistry. Synthesis Terpyridine was first synthesized by G. Morgan and F. H. Burstall in 1932 by the oxidative coupling of pyridines. This method, however, proceeded in low yields. More efficient syntheses have since been described, mainly starting from 2-acetylpyridine. One method produces an enaminone by the reaction of 2-acetylpyridine with N,N-dimethylformamide dimethyl acetal. The base-catalyzed reaction of 2-acetylpyridine with carbon disulfide followed by alkylation with methyl iodide gives C5H4NCOCH=C(SMe)2. Condensation of this species with 2-acetylpyridine forms the related 1,5-diketone, which condenses with ammonium acetate to form a terpyridine. Treatment of this derivative with Raney nickel removes the thioether group. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CSD CIF KOLGIB
CSD may refer to: Finance * Central securities depository * Confederate States Dollar * Serbian dinar, by previous ISO 4217 code Organizations Education * California School for the Deaf (other), several institutions * Canyons School District, in Utah, US * Cheltenham School District, in Pennsylvania, US * Christina School District, in Delaware, US * Cleveland School District, in Mississippi, US * Cordova School District, in Alaska, US Other organizations * Canteen Stores Department (India), a chain of stores operated by the Indian Ministry of Defence at military bases * CSD Pakistan (Canteen Stores Department), a chain of stores operated by the Pakistani Ministry of Defence * Chartered Society of Designers, a British learned society for various kinds of design work * Commission on Sustainable Development (1992–2013), a former UN agency * Communication Service for the Deaf, an American non-profit company providing ASL services * Congress of Democratic Trade Union ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EDTA
Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula . This white, slightly water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly. Uses EDTA is widely used in industry. It also has applications in food preservation, medicine, cosmetics, water softening, in laboratories, and other fields. Industrial EDTA is mainly used to sequester (bind or confine) metal ions in aqueous solution. In the textile industry, it prevents metal ion impurities from modifying colours of dyed products. In the pulp and paper industry, EDTA inhibits the ability of metal ions, especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexadentate Ligand
A hexadentate ligand in coordination chemistry is a ligand that combines with a central metal atom with six bonds. One example of a hexadentate ligand that can form complexes with soft metal ions is TPEN. A commercially important hexadentate ligand is EDTA. The denticity of hexadentate ligands is often denoted with the prefix κ6. Topology The way the donor atoms are joined together in the molecule is its topology. Some topologies are simple, such as the linear or ring shapes. The molecule can also be branched, either at a donor atom, or at a non-donor atom. Example shapes are the tripod, and amplector, with a bifurcation at each end. Rigid molecules can be used to force unusual coordination such as trigonal prism In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The oc .... F. Lions identif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentadentate Ligand
A pentadentate ligand is a ligand that coordinates via five donor atoms. There are different possible ways for a ligand to arrange around an ion. For an octahedral coordination with six positions, the possible arrangements of a linear pentadentate ligand are designated by ''ffms ffma fff fmf fmama fmsma fmsms fmams'' where each letter f or s represents three consecutive donor atoms: ''f'' represents facial ''fac'' arrangement, ''m'' is meridianal ''mer'' a is "anti" and s is "syn" for positioning of the mer arrangement relative to other donors. For a chain branched at the donor atom the tertiary atom will have two chains of length one and one of length one attached. The pattern can use parenthesis: () to indicate a side chain, eg NNM(N)N. For octahedral coordination there are four arrangements designated: ''f(m)m f(f)f f(f)ma'' and ''f(f)ms'' where the parenthesis ow indicate how the side chain participates in coordination. Ligands with four donor atoms on four chains around a ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme
Heme (American English), or haem (Commonwealth English, both pronounced /Help:IPA/English, hi:m/ ), is a ring-shaped iron-containing molecule that commonly serves as a Ligand (biochemistry), ligand of various proteins, more notably as a Prosthetic group, component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 Vinyl group, vinyl and 2 propionic acid side chains. Heme is biosynthesized in both the bone marrow and the liver. Heme plays a critical role in multiple different redox reactions in mammals, due to its ability to carry the oxygen molecule. Reactions include oxidative metabolism (cytochrome c oxidase, succinate dehydrogenase), xenobiotic detoxification via cytochrome P450 pathways (including Drug metabolism, metabolism of some drugs), gas sensing (Guanylate cyclase, guanyl cyclases, nitric oxide synthase), and microRNA processing (DGCR8). Heme is a coordination complex "consisting of an iron ion coordinated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyrin
Porphyrins ( ) are heterocyclic, macrocyclic, organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (). In vertebrates, an essential member of the porphyrin group is heme, which is a component of hemoproteins, whose functions include carrying oxygen in the bloodstream. In plants, an essential porphyrin derivative is chlorophyll, which is involved in light harvesting and electron transfer in photosynthesis. The parent of porphyrins is porphine, a rare chemical compound of exclusively theoretical interest. Substituted porphines are called porphyrins. With a total of 26 π-electrons the porphyrin ring structure is a coordinated aromatic system. One result of the large conjugated system is that porphyrins absorb strongly in the visible region of the electromagnetic spectrum, i.e. they are deeply colored. The name "porphyrin" derives . Structure Porphyrin complexes consist of a square planar MN4 core. The p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macrocycle
Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. Synthesis The formation of macrocycles by ring-closure is called macrocyclization. The central challenge to macrocyclization is that ring-closing reactions do not favor the formation of large rings. Instead, medium sized rings or polymers tend to form. Early macrocyclizations were achieved ketonic decarboxylations for the preparation of terpenoid macrocycles. So, while Ružička was able to produce various macrocycles, the yields were low. This kinetic problem can be addressed by using high-dilution reactions, whereby intramolecular processes are favored relative to polymerizations. Reactions amenable to high dilution include Dieckmann condensation and related based-induced reactions of esters with remote halides. Some macrocyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tris(2-aminoethyl)amine
Tris(2-aminoethyl)amine is the organic compound with the chemical formula, formula N(CH2CH2NH2)3. This colourless liquid is soluble in water and is highly basic, consisting of a tertiary amine center and three pendant primary amine groups. Tris(2-aminoethyl)amine is commonly abbreviated as tren or TREN. It is used a crosslinking agent in the synthesis of polyimine networks and a tripodal ligand in coordination chemistry. Supramolecular and polymer derivatives Tris(2-aminoethyl)amine has been used to prepare molecular capsules and related supramolecular structures. Metal complexes Tren is a C3-symmetric, tetradentate chelating ligand that forms stable complexes with transition metals, especially those in the 2+ and 3+ oxidation states. Tren complexes exist with relatively few isomers, reflecting the constrained connectivity of this tetramine. Thus, only a single achiral stereoisomer exists for [Co(tren)X2]+, where X is halide or pseudohalide. In contrast, for [Co(trien)X2]+ five di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
