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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] |
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] |
Porphin
Porphine or porphin is an organic chemical compound with formula . The molecule, which is flat, consists of four pyrrole-like rings joined by four methine (= C H−) groups to form a larger macrocycle ring, which makes it the simplest of the tetrapyrroles. It is classified as an aromatic and heterocyclic compound. Porphine is only of theoretical interest. It has been detected in GC-MS of certain fractions of ''Piper betle''. Porphine derivatives: porphyrins Substituted derivatives of porphine are called porphyrins. Many porphyrins are found in nature with the dominant example being protoporphyrin IX. Many synthetic porphyrins are also known, including octaethylporphyrin and tetraphenylporphyrin. File:PPIXtransH.png, Derivatives of protoporphyrin IX are common in nature, the precursor to hemes. File:H2octaethylporphyrin.png , Octaethylporphyrin (H2OEP) is a synthetic analogue of protoporphyrin IX. Unlike the natural porphyrin ligands, OEP2− is highly symmetrical. File ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protoporphyrin IX
Protoporphyrin IX is an organic compound, classified as a porphyrin, that plays an important role in living organisms as a precursor to other critical compounds like heme (hemoglobin) and chlorophyll. It is a deeply colored solid that is not soluble in water. The name is often abbreviated as PPIX. Protoporphyrin IX contains a porphine core, a tetrapyrrole macrocycle with a marked aromatic character. Protoporphyrin IX is essentially planar, except for the N-H bonds that are bent out of the plane of the rings, in opposite (trans) directions. Nomenclature The general term protoporphyrin refers to porphine derivatives that have the outer hydrogen atoms in the four pyrrole rings replaced by other functional groups. The prefix proto often means 'first' in science nomenclature (such as carbon protoxide), hence Hans Fischer is thought to have coined the name protoporphyrin as the first class of porphyrins. Fischer described iron-deprived heme becoming the "proto-" porphyrin, particu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphine
Porphine or porphin is an organic chemical compound with formula . The molecule, which is flat, consists of four pyrrole-like rings joined by four methine (= C H−) groups to form a larger macrocycle ring, which makes it the simplest of the tetrapyrroles. It is classified as an aromatic and heterocyclic compound. Porphine is only of theoretical interest. It has been detected in GC-MS of certain fractions of ''Piper betle''. Porphine derivatives: porphyrins Substituted derivatives of porphine are called porphyrins. Many porphyrins are found in nature with the dominant example being protoporphyrin IX. Many synthetic porphyrins are also known, including octaethylporphyrin and tetraphenylporphyrin. File:PPIXtransH.png, Derivatives of protoporphyrin IX are common in nature, the precursor to hemes. File:H2octaethylporphyrin.png , Octaethylporphyrin (H2OEP) is a synthetic analogue of protoporphyrin IX. Unlike the natural porphyrin ligands, OEP2− is highly symmetrical. File ... [...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] |
Tetraphenylporphyrin
Tetraphenylporphyrin, abbreviated TPP or H2TPP, is a synthetic heterocyclic compound that resembles naturally occurring porphyrins. Porphyrins are dyes and cofactors found in hemoglobin and cytochromes and are related to chlorophyll and vitamin B12. The study of naturally occurring porphyrins is complicated by their low symmetry and the presence of polar substituents. Tetraphenylporphyrin is hydrophobic, symmetrically substituted, and easily synthesized. The compound is a dark purple solid that dissolves in nonpolar organic solvents such as chloroform and benzene. Synthesis and structure Tetraphenylporphyrin was first synthesized in 1935 by Rothemund, who caused benzaldehyde and pyrrole to react in a sealed bomb at 150 °C for 24 h. Adler and Longo modified the Rothemund method by allowing benzaldehyde and pyrrole to react for 30 min in refluxing propionic acid (141 °C) open to the air: :8 C4H4NH + 8 C6H5CHO + 3 O2 → 2 (C6H5C)4(C4H2N)2(C4H2NH)2 + 14 H2O D ... [...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] |
Conjugated System
In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability. It is conventionally represented as having alternating single and multiple bonds. Lone pairs, radicals or carbenium ions may be part of the system, which may be cyclic, acyclic, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele. Conjugation is the overlap of one p-orbital with another across an adjacent σ bond (in transition metals, d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent locations that simple diagrams illustrate as not having a π bond. They allow a delocalization of π electrons across all the adjacent aligned p-orbitals. The π electrons do not belong to a single bond or atom, but rather to a group of atoms. Molecules containing conjugated syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abelsonite
Abelsonite is a nickel porphyrin mineral with chemical formula C31H32N4Ni. It was discovered in 1969 in the U.S. State of Utah and described in 1975. The mineral is named after geochemist Philip H. Abelson. It is the only known crystalline geoporphyrin. Description Abelsonite is semitransparent and pink-purple, dark greyish purple, pale purplish red, or reddish brown in color. The mineral occurs as thin laths or plates or small aggregates up to . The mineral is soluble in benzene and acetone and is insoluble in water, dilute hydrochloric acid, and dilute nitric acid. Occurrence and formation The mineral is known only from the Parachute Creek Member of the Green River Formation. It has been known from the Uinta Basin in Utah since its discovery and from the Piceance Basin in Colorado since 1985. Abelsonite occurs in association with albite, analcime, dolomite, mica, orthoclase, pyrite, and quartz. Abelsonite is a secondary mineral that formed in fractures, vugs, and bedding pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Crude Oil
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, mostly zooplankton and algae, are buried underneath sedimentary rock and subjected to both prolonged heat and pressure. Petroleum is primarily recovered by oil drilling. Drilling is carried out after studies of structural geology, sedimentary basin analysis, and reservoir characterisation. Recent developments in technologies have also led to exploitation of other Unconventional (oil & gas) reservoir, unconventional reserves such as oil sands and oil shale. Once extracted, oil is refined and separated, most easily by Continuous distillation#Continuous distillation of crude oil, distillation, into innume ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier
Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, '' Trends'', the '' Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services also include digital tools for data management, instruction, research analytics and assessment. Elsevier is part of the RELX Group (known until 2015 as Reed Elsevier), a publicly traded company. According to RELX reports, in 2021 Elsevier published more than 600,000 articles annually in over 2,700 journals; as of 2018 its archives contained over 17 million documents and 40,000 e-books, with over one billion annual downloads. Researchers have criticized Elsevier for its high profit marg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
