Photoisomerization: Difference between revisions

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Photoisomerization

Azobenzene photoisomerization

Photoisomerization is a process in which a molecule undergoes a structural change upon absorption of light. This phenomenon is a type of photochemical reaction and is significant in various fields such as chemistry, biology, and materials science.

Mechanism

Photoisomerization involves the conversion of a molecule from one isomeric form to another. This process is typically initiated by the absorption of a photon, which provides the energy necessary to overcome the activation barrier between isomers. The most common types of photoisomerization involve cis-trans isomerism and ring-opening reactions.

Cis-Trans Isomerization

Cis-trans isomerization example

In cis-trans isomerization, a molecule with a double bond or a similar structural feature changes from a cis (same side) to a trans (opposite side) configuration, or vice versa. This type of isomerization is common in azobenzene compounds, which are widely studied for their reversible photoisomerization properties.

Ring-Opening Reactions

Ring-opening reactions involve the conversion of a cyclic molecule to an acyclic form. An example is the conversion of norbornadiene to quadricyclane, which is a photoinduced process that stores energy in the form of chemical bonds.

Applications

Photoisomerization has numerous applications across different scientific disciplines. In biology, it plays a crucial role in vision, where the photoisomerization of retinal is a key step in the phototransduction pathway. In materials science, photoisomerizable compounds are used in the development of molecular switches and light-responsive materials.

Dyes and Pigments

Photoisomerization is also important in the field of dyes and pigments. Compounds like methyl red undergo structural changes upon exposure to light, which can alter their color and are used as pH indicators.

Molecular Machines

Photoisomerizable molecules are integral to the design of molecular machines and nanotechnology. These molecules can act as switches or motors, changing their conformation in response to light and performing mechanical work at the molecular level.

Examples

Azobenzene

Azobenzene is one of the most studied photoisomerizable compounds. It can switch between its trans and cis forms upon exposure to UV and visible light, respectively. This property makes azobenzene a popular choice for applications in optical data storage and smart materials.

Metal Complexes

Certain metal complexes also exhibit photoisomerization. These complexes can change their geometry or coordination upon light absorption, which can be utilized in catalysis and photopharmacology.

Related pages

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-== Photoisomerization ==
+Photoisomerization
-'''Photoisomerization''' is a process in which a molecule undergoes a structural change upon absorption of light. This phenomenon is a type of [[isomerization]] that is specifically induced by [[photons]], typically in the [[ultraviolet]] or [[visible spectrum]]. Photoisomerization plays a crucial role in various biological processes and technological applications.
+[[File:AzobenzeneIsom_no_Engl.png|thumb|right|Azobenzene photoisomerization]]
-=== Mechanism ===
+'''Photoisomerization''' is a process in which a molecule undergoes a structural change upon absorption of light. This phenomenon is a type of [[photochemical reaction]] and is significant in various fields such as [[chemistry]], [[biology]], and [[materials science]].
-Photoisomerization involves the conversion of a molecule from one [[isomer]] to another. This process is initiated when a molecule absorbs a photon, which provides the energy necessary to overcome the energy barrier between isomers. The absorbed energy excites the molecule from its ground state to an excited state, allowing it to undergo a structural rearrangement.
+==Mechanism==
+Photoisomerization involves the conversion of a molecule from one isomeric form to another. This process is typically initiated by the absorption of a photon, which provides the energy necessary to overcome the activation barrier between isomers. The most common types of photoisomerization involve [[cis-trans isomerism]] and [[ring-opening reactions]].
-[[File:Photoisomerization.svg|thumb|right|300px|Diagram illustrating the photoisomerization process.]]
+===Cis-Trans Isomerization===
+[[File:Cis-trans-PtCl2P2.png|thumb|left|Cis-trans isomerization example]]
+In cis-trans isomerization, a molecule with a double bond or a similar structural feature changes from a cis (same side) to a trans (opposite side) configuration, or vice versa. This type of isomerization is common in [[azobenzene]] compounds, which are widely studied for their reversible photoisomerization properties.
-In many cases, the isomerization involves a change in the configuration around a [[double bond]], such as the conversion between [[cis]] and [[trans]] isomers. For example, in the case of [[retinal]], a key molecule in the [[visual cycle]], photoisomerization changes the configuration from 11-cis-retinal to all-trans-retinal, triggering a signal transduction cascade in [[photoreceptor cells]].
+===Ring-Opening Reactions===
+[[File:Synthesis_of_quadricyclane_from_norbornadiene.png|thumb|right|Ring-opening of norbornadiene to quadricyclane]]
+Ring-opening reactions involve the conversion of a cyclic molecule to an acyclic form. An example is the conversion of [[norbornadiene]] to [[quadricyclane]], which is a photoinduced process that stores energy in the form of chemical bonds.
-=== Biological Significance ===
+==Applications==
+Photoisomerization has numerous applications across different scientific disciplines. In [[biology]], it plays a crucial role in vision, where the photoisomerization of [[retinal]] is a key step in the phototransduction pathway. In [[materials science]], photoisomerizable compounds are used in the development of [[molecular switches]] and [[light-responsive materials]].
-Photoisomerization is essential in several biological systems. One of the most well-known examples is the role of retinal in [[vision]]. In the [[retina]], retinal is bound to the protein [[opsin]] to form [[rhodopsin]]. When rhodopsin absorbs light, retinal undergoes photoisomerization, leading to a conformational change in the protein and the initiation of a neural signal to the brain.
+===Dyes and Pigments===
+[[File:Methyl_red.svg|thumb|left|Methyl red, a pH indicator]]
+Photoisomerization is also important in the field of dyes and pigments. Compounds like [[methyl red]] undergo structural changes upon exposure to light, which can alter their color and are used as [[pH indicators]].
-Another example is the photoisomerization of [[phytochromes]] in plants, which are involved in regulating growth and development in response to light. Phytochromes exist in two forms, Pr and Pfr, which interconvert through photoisomerization, allowing plants to sense changes in light conditions.
+===Molecular Machines===
+Photoisomerizable molecules are integral to the design of [[molecular machines]] and [[nanotechnology]]. These molecules can act as switches or motors, changing their conformation in response to light and performing mechanical work at the molecular level.
-=== Technological Applications ===
+==Examples==
-Photoisomerization is utilized in various technological applications, including the development of [[molecular switches]] and [[photoresponsive materials]]. These materials can change their properties in response to light, making them useful in [[optical data storage]], [[smart windows]], and [[drug delivery systems]].
+===Azobenzene===
+Azobenzene is one of the most studied photoisomerizable compounds. It can switch between its trans and cis forms upon exposure to UV and visible light, respectively. This property makes azobenzene a popular choice for applications in [[optical data storage]] and [[smart materials]].
-[[File:Azobenzene.png|thumb|left|200px|Azobenzene, a common photoisomerizable compound used in molecular switches.]]
+===Metal Complexes===
+[[File:Fe(picNH2)3.png|thumb|right|Photoisomerization in metal complexes]]
+Certain metal complexes also exhibit photoisomerization. These complexes can change their geometry or coordination upon light absorption, which can be utilized in [[catalysis]] and [[photopharmacology]].
-One of the most studied photoisomerizable compounds is [[azobenzene]], which can switch between its trans and cis forms upon exposure to light. This property is exploited in the design of [[photochromic]] devices and [[nanomachines]].
+==Related pages==
-== Related Pages ==
-* [[Isomerization]]
 * [[Photochemistry]]
-* [[Retinal]]
+* [[Isomerism]]
-* [[Rhodopsin]]
+* [[Molecular switch]]
-* [[Phytochrome]]
+* [[Retinal (molecule)]]
-* [[Azobenzene]]
-{{Photochemistry}}
 [[Category:Photochemistry]]
 [[Category:Isomerism]]
-[[Category:Biochemistry]]