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Octaethylporphyrin
Octaethylporphyrin (H2OEP) is an organic compound that is a relative of naturally occurring heme pigments. The compound is used in the preparation of models for the prosthetic group in heme proteins. It is a dark purple solid that is soluble in organic solvents. As its conjugate base OEP2-, it forms a range of transition metal porphyrin complexes. When treated with ferric chloride in hot acetic acid solution, it gives the square pyramidal complex Fe(OEP)Cl. It also forms the square planar complexes Ni(OEP) and Cu(OEP). Contrast with other porphyrins Unlike complexes of the naturally occurring porphyrins, OEP complexes have four-fold symmetry, which simplifies spectroscopic analysis. In contrast to tetraphenylporphyrin and related analogues, H2OEP features unprotected meso positions. In this way, it is a more accurate model for naturally occurring porphyrins. Synthesis H2OEP is prepared by condensation of 3,4-diethylpyrrole with formaldehyde Formaldehyde ( , ) (systema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyrin
Porphyrins ( ) are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent of porphyrin is porphine, a rare chemical compound of exclusively theoretical interest. Substituted porphines are called porphyrins. With a total of 26 π-electrons, of which 18 π-electrons form a planar, continuous cycle, the porphyrin ring structure is often described as aromatic. One result of the large conjugated system is that porphyrins typically absorb strongly in the visible region of the electromagnetic spectrum, i.e. they are deeply colored. The name "porphyrin" derives from the Greek word πορφύρα (''porphyra''), meaning ''purple''. Complexes of porphyrins Concomitant with the displacement of two N-''H'' protons, porphyrins bind metal ions in the N4 "pocket". The metal ion usually has a charge of 2+ or 3+. A schematic equation for these syntheses is shown: :H2porp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme
Heme, or haem (pronounced / hi:m/ ), is a precursor to hemoglobin, which is necessary to bind oxygen in the bloodstream. Heme is biosynthesized in both the bone marrow and the liver. In biochemical terms, heme is a coordination complex "consisting of an iron ion coordinated to a porphyrin acting as a tetradentate ligand, and to one or two axial ligands." The definition is loose, and many depictions omit the axial ligands. Among the metalloporphyrins deployed by metalloproteins as prosthetic groups, heme is one of the most widely used and defines a family of proteins known as hemoproteins. Hemes are most commonly recognized as components of hemoglobin, the red pigment in blood, but are also found in a number of other biologically important hemoproteins such as myoglobin, cytochromes, catalases, heme peroxidase, and endothelial nitric oxide synthase. The word ''haem'' is derived from Greek ''haima'' meaning "blood". Function Hemoproteins have diverse biological functions incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal Porphyrin Complexes
220px, A picket-fence porphyrin complex of Fe, with axial coordination sites occupied by methylimidazole (green) and dioxygen (R = amide groups). Transition metal porphyrin complexes are a family of coordination complexes of the conjugate base of porphyrins. Iron porphyrin complexes occur widely in Nature, which has stimulated extensive studies on related synthetic complexes. The metal-porphyrin interaction is a strong one such that metalloporphyrins are thermally robust. They are catalysts and exhibit rich optical properties, although these complexes remain mainly of academic interest. Formation Metal porphyrin complexes are almost always prepared by direct reaction of a metal halide with the free porphyrin, abbreviated here as H2P: :MClx + H2P → M(P)Cl2−x + 2HCl Two pyrrole protons are lost. The porphyrin dianion is an L2X2 ligand. These syntheses require somewhat forcing conditions, consistent with the tight fit of the metal in the N42- "pocket." In nature, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferric Chloride
Iron(III) chloride is the inorganic compound with the formula . Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The colour depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red. Structure and properties Anhydrous Anhydrous iron(III) chloride has the structure, with octahedral Fe(III) centres interconnected by two-coordinate chloride ligands. Iron(III) chloride has a relatively low melting point and boils at around 315 °C. The vapor consists of the dimer (like aluminium chloride) which increasingly dissociates into the monomeric (with D3h point group molecular symmetry) at higher temperature, in competition with its reversible decomposition to give iron(II) chloride and chlorine gas. Hydrates In addition to the anhydrous material, ferric chloride forms four hydrates. All f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H2OEP In DCM
H, or h, is the eighth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''aitch'' (pronounced , plural ''aitches''), or regionally ''haitch'' ."H" ''Oxford English Dictionary,'' 2nd edition (1989); ''Merriam-Webster's Third New International Dictionary of the English Language, Unabridged'' (1993); "aitch" or "haitch", op. cit. History The original Semitic letter Heth most likely represented the voiceless pharyngeal fricative (). The form of the letter probably stood for a fence or posts. The Greek Eta 'Η' in archaic Greek alphabets, before coming to represent a long vowel, , still represented a similar sound, the voiceless glottal fricative . In this context, the letter eta is also known as Heta to underline this fact. Thus, in the Old Italic alphabets, the letter Heta of the Euboean alphabet was adopted with its original sound value . While Etruscan and La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section Forms below), hence it is stored as an aqueous solution (formalin), which is also used to store animal specimens. It is the simplest of the aldehydes (). The common name of this substance comes from its similarity and relation to formic acid. Formaldehyde is an important precursor to many other materials and chemical compounds. In 1996, the installed capacity for the production of formaldehyde was estimated at 8.7 million tons per year. It is mainly used in the production of industrial resins, e.g., for particle board and coatings. Forms Formaldehyde is more complicated than many simple carbon compounds in that it adopts several diverse forms. These compounds can often be used interchangeably and can be interconverted. *Molecular formald ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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