Porphyrin
Overview
 
Porphyrins are a group of organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s, many naturally occurring. One of the best-known porphyrins is heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

, the pigment in red blood cell
Blood cell
A blood cell, also called a hematocyte, is a cell normally found in blood. In mammals, these fall into three general categories:* red blood cells — Erythrocytes* white blood cells — Leukocytes* platelets — Thrombocytes...

s; heme is a cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 of the protein hemoglobin. Porphyrins are heterocyclic macrocycle
Macrocycle
A macrocycle is, as defined by IUPAC, "a cyclic macromolecule or a macromolecular cyclic portion of a molecule." In the chemical literature, organic chemists may consider any molecule containing a ring of nine or more atoms to be a macrocycle...

s composed of four modified pyrrole
Pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...

 subunits interconnected at their α carbon atoms via methine
Methine
In chemistry, methine is a trivalent functional group CH, derived formally from methane. The methine group consists of a carbon atom bound by two single bonds and one double bond, where one of the single bonds is to a hydrogen...

 bridges (=CH-). Porphyrins are aromatic
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

. That is, they obey Hückel's rule
Hückel's rule
In organic chemistry, Hückel's rule estimates whether a planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931...

 for aromaticity, possessing 4n+2 π electrons (n=4 for the shortest cyclic path) delocalized over the macrocycle.
Encyclopedia
Porphyrins are a group of organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s, many naturally occurring. One of the best-known porphyrins is heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

, the pigment in red blood cell
Blood cell
A blood cell, also called a hematocyte, is a cell normally found in blood. In mammals, these fall into three general categories:* red blood cells — Erythrocytes* white blood cells — Leukocytes* platelets — Thrombocytes...

s; heme is a cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 of the protein hemoglobin. Porphyrins are heterocyclic macrocycle
Macrocycle
A macrocycle is, as defined by IUPAC, "a cyclic macromolecule or a macromolecular cyclic portion of a molecule." In the chemical literature, organic chemists may consider any molecule containing a ring of nine or more atoms to be a macrocycle...

s composed of four modified pyrrole
Pyrrole
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colourless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3...

 subunits interconnected at their α carbon atoms via methine
Methine
In chemistry, methine is a trivalent functional group CH, derived formally from methane. The methine group consists of a carbon atom bound by two single bonds and one double bond, where one of the single bonds is to a hydrogen...

 bridges (=CH-). Porphyrins are aromatic
Aromaticity
In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

. That is, they obey Hückel's rule
Hückel's rule
In organic chemistry, Hückel's rule estimates whether a planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931...

 for aromaticity, possessing 4n+2 π electrons (n=4 for the shortest cyclic path) delocalized over the macrocycle. Thus porphyrin macrocycles are highly conjugated system
Conjugated system
In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in compounds with alternating single and multiple bonds, which in general may lower the overall energy of the molecule and increase stability. Lone pairs, radicals or carbenium ions may be part of the...

s. As a consequence, they typically have very intense absorption bands in the visible region and may be deeply colored; the name porphyrin comes from a Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 word for purple
Purple
Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade....

. The macrocycle has 26 pi electrons in total. The parent porphyrin is porphine, and substituted porphines are called porphyrins.

Complexes of porphyrins and related molecules

Porphyrins are the conjugate acids of ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

s that bind metals to form complexes
Complex (chemistry)
In chemistry, a coordination complex or metal complex, is an atom or ion , bonded to a surrounding array of molecules or anions, that are in turn known as ligands or complexing agents...

. The metal ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 usually has a charge of 2+ or 3+. A schematic equation for these syntheses is shown:
H2porphyrin + [MLn]2+ → M(porphyrinate)Ln-4 + 4 L + 2 H+ where M=metal ion and L=a ligand

A porphyrin without metal in its cavity is a free base. Some iron-containing porphyrins are called hemes. Heme-containing protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s, or hemoprotein
Hemoprotein
A hemeprotein , or heme protein, is a metalloprotein containing a heme prosthetic group- an organic compound that allows a protein to carry out a function that it cannot do alone....

s
, are found extensively in nature. Hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 and myoglobin
Myoglobin
Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells. The only time myoglobin is found in the...

 are two O2
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

-binding proteins that contain iron porphyrins. Various cytochrome
Cytochrome
Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....

s are also hemoproteins.

Several other heterocycles are related to porphyrins. These include corrin
Corrin
Corrin is an heterocyclic compound. It is the parent macrocycle related to substituted derivative that is found in vitamin B12. Its name reflects that it is the "core" of vitamin B12 .-Coordination chemistry:...

s, chlorin
Chlorin
In organic chemistry, a chlorin is a large heterocyclic aromatic ring consisting, at the core, of three pyrroles and one pyrroline coupled through four methine linkages...

s, bacteriochlorophyll
Bacteriochlorophyll
Bacteriochlorophylls are photosynthetic pigments that occur in various phototrophic bacteria. They were discovered by Von Neil in 1932 . They are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria. Groups that contain bacteriochlorophyll conduct...

s, and corphins
Cofactor F430
F430 is the prosthetic group of the enzyme methyl coenzyme M reductase. It is found only in methanogenic Archaea. This enzyme catalyzes the release of methane in the final step of methanogenesis:-Corphin in context:...

. Chlorin
Chlorin
In organic chemistry, a chlorin is a large heterocyclic aromatic ring consisting, at the core, of three pyrroles and one pyrroline coupled through four methine linkages...

s (2,3-dihydroporphyrin) are more reduced, contain more hydrogen than porphyrins, and feature a pyrroline
Pyrroline
Pyrrolines, also known under the name dihydropyrroles, are three different heterocyclic organic chemical compounds that differ in the position of the double bond. Pyrrolines are formally derived from the aromate pyrrole by hydrogenation...

 subunit. This structure occurs in a chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

 molecule. Replacement of two of the four pyrrolic subunits with pyrrolinic subunits results in either a bacteriochlorin (as found in some photosynthetic bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

) or an isobacteriochlorin, depending on the relative positions of the reduced rings. Some porphyrin derivatives follow Hückel's rule, but most do not.

Biosynthesis

The "committed step" for porphyrin biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...

 is the formation of δ-aminolevulinic acid (δ-ALA, 5-ALA or dALA) by the reaction of the amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 glycine
Glycine
Glycine is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.Glycine is a colourless, sweet-tasting crystalline solid...

 with succinyl-CoA
Succinyl-CoA
Succinyl-Coenzyme A, abbreviated as Succinyl-CoA or SucCoA, is a combination of succinic acid and coenzyme A.-Source:It is an important intermediate in the citric acid cycle, where it is synthesized from α-Ketoglutarate by α-ketoglutarate dehydrogenase through decarboxylation...

 from the citric acid cycle
Citric acid cycle
The citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or the Szent-Györgyi-Krebs cycle — is a series of chemical reactions which is used by all aerobic living organisms to generate energy through the oxidization of acetate derived from carbohydrates, fats and...

. Two molecules of dALA combine to give porphobilinogen
Porphobilinogen
Porphobilinogen is a pyrrole involved in porphyrin metabolism.It is generated by aminolevulinate and the enzyme ALA dehydratase. PBG is then converted into hydroxymethyl bilane by the enzyme porphobilinogen deaminase, also known as hydroxymethylbilane synthase.Acute intermittent porphyria causes...

 (PBG), which contains a pyrrole ring. Four PBGs are then combined through deamination
Deamination
Deamination is the removal of an amine group from a molecule. Enzymes which catalyse this reaction are called deaminases.In the human body, deamination takes place primarily in the liver, however glutamate is also deaminated in the kidneys. Deamination is the process by which amino acids are...

 into hydroxymethyl bilane (HMB), which is hydrolysed to form the circular tetrapyrrole uroporphyrinogen III
Uroporphyrinogen III
Uroporphyrinogen III is an metabolic intermediate in the biosynthesis of protoporphyrin. It is created by the enzyme uroporphyrinogen III synthase, and is converted into coproporphyrinogen III by the enzyme uroporphyrinogen III decarboxylase.-See also:...

. This molecule undergoes a number of further modifications. Intermediates are used in different species to form particular substances, but, in humans, the main end-product protoporphyrin IX
Protoporphyrin IX
Protoporphyrin IX, in the metabolism of porphyrin, is created by the enzyme protoporphyrinogen oxidase.-Heme b biosynthesis:In heme biosynthesis, the enzyme ferrochelatase converts it into heme b Protoporphyrin IX, in the metabolism of porphyrin, is created by the enzyme protoporphyrinogen...

 is combined with iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 to form heme. Bile pigments are the breakdown products of heme.

The following scheme summarizes the biosynthesis of porphyrins, with references by EC number and the OMIM database. The porphyria
Porphyria
Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...

 associated with the deficiency of each enzyme is also shown:

Enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

Location Substrate
Substrate (biochemistry)
In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...

Product Chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

EC
EC number
The Enzyme Commission number is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze....

OMIM Porphyria
Porphyria
Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...

ALA synthase Mitochondrion Glycine
Glycine
Glycine is an organic compound with the formula NH2CH2COOH. Having a hydrogen substituent as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG cf. the genetic code.Glycine is a colourless, sweet-tasting crystalline solid...

, succinyl CoA
δ-Aminolevulinic acid 3p21.1 2.3.1.37 125290 none
ALA dehydratase Cytosol δ-Aminolevulinic acid Porphobilinogen 9q34 4.2.1.24 125270 ALA-Dehydratase deficiency
PBG deaminase
Porphobilinogen deaminase
Porphobilinogen deaminase is an enzyme involved in the third step of the metabolism of porphyrin, converting porphobilinogen into hydroxymethylbilane. The enzyme has the unique cofactor dipyrromethane...

Cytosol Porphobilinogen
Porphobilinogen
Porphobilinogen is a pyrrole involved in porphyrin metabolism.It is generated by aminolevulinate and the enzyme ALA dehydratase. PBG is then converted into hydroxymethyl bilane by the enzyme porphobilinogen deaminase, also known as hydroxymethylbilane synthase.Acute intermittent porphyria causes...

Hydroxymethyl bilane 11q23.3 2.5.1.61 176000 acute intermittent porphyria
Acute intermittent porphyria
Acute intermittent porphyria is a rare autosomal dominant metabolic disorder affecting the production of heme, the oxygen-binding prosthetic group of hemoglobin. It is characterized by a deficiency of the enzyme porphobilinogen deaminase. Acute intermittent porphyria is the second most common...

Uroporphyrinogen III synthase
Uroporphyrinogen III synthase
Uroporphyrinogen III synthase is an enzyme involved in the metabolism of the cyclic tetrapyrrole compound porphyrin. It is involved in the conversion of hydroxymethyl bilane into uroporphyrinogen III...

Cytosol Hydroxymethyl bilane Uroporphyrinogen III 10q25.2-q26.3 4.2.1.75 606938 congenital erythropoietic porphyria
Uroporphyrinogen III decarboxylase
Uroporphyrinogen III decarboxylase
Uroporphyrinogen decarboxylase, also known as UROD, is an enzyme that in humans is encoded by the UROD gene.- Function :This gene encodes the fifth enzyme of the heme biosynthetic pathway...

Cytosol Uroporphyrinogen III
Uroporphyrinogen III
Uroporphyrinogen III is an metabolic intermediate in the biosynthesis of protoporphyrin. It is created by the enzyme uroporphyrinogen III synthase, and is converted into coproporphyrinogen III by the enzyme uroporphyrinogen III decarboxylase.-See also:...

Coproporphyrinogen III 1p34 4.1.1.37 176100 porphyria cutanea tarda
Porphyria cutanea tarda
Porphyria cutanea tarda is the most common subtype of porphyria. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs...

Coproporphyrinogen III oxidase
Coproporphyrinogen III oxidase
Coproporphyrinogen-III oxidase, mitochondrial is an enzyme that in humans is encoded by the CPOX gene. A genetic defect in the enzyme results in a reduced production of heme in animals. The medical condition associated with this enzyme defect is called hereditary coproporphyria...

Mitochondrion Coproporphyrinogen III
Coproporphyrinogen III
In the metabolism of porphyrin, the enzyme uroporphyrinogen III decarboxylase generates coproporphyrinogen III from uroporphyrinogen III, and coproporphyrinogen III oxidase converts it into protoporphyrinogen IX....

Protoporphyrinogen IX 3q12 1.3.3.3 121300 coproporphyria
Protoporphyrinogen oxidase
Protoporphyrinogen oxidase
Protoporphyrinogen oxidase is an enzyme that is responsible for the seventh step in heme production....

Mitochondrion Protoporphyrinogen IX
Protoporphyrinogen IX
Protoporphyrinogen IX is a precursor for protoporphyrin IX. See Porphyrins for the pathway and more information.-See also:* Protoporphyrinogen oxidase...

Protoporphyrin IX 1q22 1.3.3.4 600923 variegate porphyria
Variegate porphyria
Variegate porphyria is an autosomal dominant porphyria that can have acute symptoms along with symptoms that affect the skin...

Ferrochelatase
Ferrochelatase
Ferrochelatase is an enzyme that catalyses the terminal step in the biosynthesis of heme, converting protoporphyrin IX into heme. It catalyses the reaction:A ferrochelatase enzyme consists of 497 amino acid residues with a m.w...

Mitochondrion Protoporphyrin IX
Protoporphyrin IX
Protoporphyrin IX, in the metabolism of porphyrin, is created by the enzyme protoporphyrinogen oxidase.-Heme b biosynthesis:In heme biosynthesis, the enzyme ferrochelatase converts it into heme b Protoporphyrin IX, in the metabolism of porphyrin, is created by the enzyme protoporphyrinogen...

Heme 18q21.3 4.99.1.1 177000 erythropoietic protoporphyria
Erythropoietic protoporphyria
Erythropoietic protoporphyria is a relatively mild form of porphyria, although very painful, which arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the tissue...


Laboratory synthesis

One of the more common syntheses for porphyrins is based on work by Paul Rothemund. His techniques underpin more modern syntheses such as those described by Adler and Longo. The synthesis of simple porphyrins such as meso-tetraphenylporphyrin
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...

 (H2TPP) is also commonly done in university teaching labs.

The Rothemund synthesis is an condensation and oxidation starting with pyrrole and an aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

. In solution-phase synthesis, acidic conditions are essential; formic acid, acetic acid, and propionic acid are typical reaction solvents, or p-toluenesulfonic acid
P-Toluenesulfonic acid
p-Toluenesulfonic acid or tosylic acid is an organic compound with the formula CH3C6H4SO3H. It is a white solid that is soluble in water, alcohols, and other polar organic solvents. The 4-CH3C6H4SO2- group is known as the Tosyl group and is often abbreviated as Ts or Tos...

 or various Lewis acids can be used with a non-acidic solvent. A large amount of side-product is formed and is removed, usually by recrystallization or chromatography.


Modern green chemistry
Green chemistry
Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances...

 variants have been developed in which the reaction is performed adsorbed on acidic silica gel
Silica gel
Silica gel is a granular, vitreous, porous form of silica made synthetically from sodium silicate. Despite its name, silica gel is a solid. It is a naturally occurring mineral that is purified and processed into either granular or beaded form...

 with microwave irradiation
Microwave chemistry
Microwave chemistry is the science of applying microwave irradiation to chemical reactions. Microwaves act as high frequency electric fields and will generally heat any material containing mobile electric charges, such as polar molecules in a solvent or conducting ions in a solid...

 or at high temperature in the gas phase. In these cases, no additional acid is required.

Applications

Although natural porphyrin complexes are essential for life, synthetic porphyrins and their complexes have limited utility. Complexes of meso-tetraphenylporphyrin
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...

, e.g., the iron(III) chloride complex (TPPFeCl), catalyze a variety of reactions in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, but none of them are of practical value. Porphyrin-based compounds are of interest in molecular electronics
Molecular electronics
Molecular electronics, sometimes called moletronics, involves the study and application of molecular building blocks for the fabrication of electronic components...

 and supramolecular building blocks. Phthalocyanine
Phthalocyanine
Phthalocyanine is an intensely blue-green coloured macrocyclic compound that is widely used in dyeing. Phthalocyanines form coordination complexes with most elements of the periodic table...

s, which are structurally related to porphyrins, are used in commerce as dyes and catalysts. Synthetic porphyrin dyes that are incorporated in the design of solar cells are the subject of ongoing research. (See dye-sensitized solar cells
Dye-sensitized solar cells
A dye-sensitized solar cell is a low-cost solar cell belonging to the group of thin film solar cells. It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system...

.)

In 2008, the corporation Destiny Pharma Ltd reported successful clinical trials of an intra-nasally applied porphyrin XF-73
XF-73
XF-73 is an experimental drug candidate. It is an anti-microbial which works via weakening bacteria cell walls. It is a potential treatment for methicillin-resistant Staphylococcus aureus and possibly Clostridium difficile...

 against methicillin-resistant Staphylococcus aureus.

Supramolecular chemistry

Porphyrins are often used to construct structures in supramolecular chemistry
Supramolecular chemistry
Supramolecular chemistry refers to the area of chemistry beyond the molecules and focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components...

. These systems take advantage of the Lewis acidity of the metal, typically zinc. An example of a host-guest complex that was constructed from a macrocycle
Macrocycle
A macrocycle is, as defined by IUPAC, "a cyclic macromolecule or a macromolecular cyclic portion of a molecule." In the chemical literature, organic chemists may consider any molecule containing a ring of nine or more atoms to be a macrocycle...

 composed of four porphyrins. A guest-free base porphyrin is bound to the center by coordination with its four-pyridine substituents.

Organic geochemistry

The field of organic geochemistry
Organic geochemistry
Organic geochemistry is the study of the impacts and processes that organisms have had on the Earth. The study of organic geochemistry is usually traced to the work of Alfred E. Treibs, "the father of organic geochemistry." Treibs first isolated metalloporphyrins from petroleum. This discovery...

, the study of the impacts and processes that organisms have had on the Earth, had its origins in the isolation of porphyrins from petroleum. This finding helped establish the biological origins of petroleum. Petroleum is sometimes "fingerprinted" by analysis of trace amounts of nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

 and vanadyl porphyrins.

Chlorophyll is a magnesium porphyrin, and heme is an iron porphyrin, but neither porphyrin is present in petroleum. On the other hand, nickel and vanadyl porphyrins could be related to catalytic molecules from bacteria that feed primordial hydrocarbons.

See also

  • A porphyrin-related disease: porphyria
    Porphyria
    Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...

  • Porphyrin coordinated to iron: heme
    Heme
    A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

  • A heme-containing group of enzymes: Cytochrome P450
  • Porphyrin coordinated to magnesium: chlorophyll
    Chlorophyll
    Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

  • The one-carbon-shorter analogues: corrole
    Corrole
    A corrole is an aromatic organic chemical, whose structure is in the form of the corrin ring which is also present in cobalamin . The ring consists of nineteen carbon atoms, with four nitrogen atoms in the core of the molecule....

    s, including vitamin B12
    Vitamin B12
    Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...

    , which is coordinated to a cobalt
  • Corphins, the highly reduced porphyrin coordinated to nickel that binds the F430 active site in methyl coenzyme M reductase (MCR)
  • Nitrogen-substituted porphyrins: phthalocyanine
    Phthalocyanine
    Phthalocyanine is an intensely blue-green coloured macrocyclic compound that is widely used in dyeing. Phthalocyanines form coordination complexes with most elements of the periodic table...


External links

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