Photoswitch, or photo-electric switch, is a sensor that detects the presence of light or a change in its intensity. Photoswitches are one type of molecular machines, a class of molecules that can be switched between at least two distinct thermodynamically stable forms by the application of an external stimulus. The development of such devices is crucial in the framework of nanotechnology;[1] nowadays, photoswitches are applied in a variety of places from scientific applications to residential light timers. Organic compounds have been deployed as photoswitches and a popular example of it is azobenzene.
Contents
1Chemistry
2Applications
2.1Issue
3References
Chemistry
In this photoswitch the photo-excitation of the azo groups triggers a mechanical response [2]
A photoswitchable molecule is a chemical that is sensitive in some way to light, e.g. able to turn on retina cells when exposed to light,.[3][4] Some examples include AAQ, DENAQ, photochromic compounds, azobenzenes, spiropyrans, diarylethenes, fulgides, overcrowded alkenes. For instance, azo compounds can isomerize by absorbing a particular wavelength of light. This photoisomerization transforms the azo group from the trans to the cis form. Novel azo carrying photoswitches are introduced as molecular hinges[2][5]which can be used in the design of molecular machines and optical devices [6].
Applications
A photo-electric cell is connected to a circuit that measures how much electricity the cell produces and according to the setting of minimum and maximum lux level, the circuit decides and gives the output.[7]
Photoswitches have recently also been used in the generation of three-dimensional animations and images [8]. The display utilizes a medium composed of a class of photoswitches (known as spirhodamines) and digital light processing (DLP) technology to generate structured light in three dimensions. UV light and green light patterns are aimed at the dye solution, which initiates photoactivation and thus creates the 'on' voxel. The device is capable of displaying a minimum voxel size of 0.68 mm^3, with 200 μm resolution, and good stability over hundreds of on-off cycles.
In the field of photopharmacology, photoswitches are used to obtain control over the activity. By including a photoswitch to the drugs, a drug with several states is created, all having their own biological activity. Light can be used to switch between these states, resulting in drugs with remote control over the activity.[9]
Issue
The issue of the photoswitch that the reflecting efficiency of the reflecting member may be drastically lowered due to dewing and clouding of the reflecting surface due to a change in the ambient temperature. The dew on the reflecting surface causes a random reflection. In order to avoid the clouding of the reflecting surface, it has been proposed to apply silicon or the like to the surface of the reflecting member. This countermeasure, however, cannot prevent condensing of dew onto the lower part of the reflecting surface. Thus, there are many problems in the prior art.[10]
References
^Sinicropi, Adalgisa (April 2010). "Biomimetic photoswitches" (PDF). La Chimica & l'Industria (in Italian). Società Chimica Italiana (3): 102–109.
^ abHunlich base derivatives as photo-responsive Ʌ-shaped hinges. Organic Chemistry Frontiers 2017, 4 (2), 224-228. https://dx.doi.org/10.1039/C6QO00653A
^"Chemical makes blind mice instantly see — without invasive surgery". Cite web requires |website= (help)
^"Kramer Lab". Retrieved 28 September 2014. Cite web requires |website= (help)
^Light-Driven Molecular Hinge: A New Molecular Machine Showing a Light-Intensity-Dependent Photoresponse that Utilizes the Trans−Cis Isomerization of Azobenzene. Org. Lett. 2004, 6 (15), 2595-2598.
^Design and synthesis of Ʌ-shaped photoswitchable compounds employing Tröger’s base scaffold. Synthesis 2017, 49 (6), 1214-1222. https://dx.doi.org/10.1055/s-0036-1588913
^PHOTOSWITCH Photoelectric Sensors
^Patel, S. K.; Cao, J.; Lippert, A. R. "A Volumetric 3D Photoactivatable Dye Display." Nature Commun. 2017, in press. https://www.nature.com/articles/ncomms15239
^Velema, Willem A.; Szymanski, Wiktor; Feringa, Ben L. (12 February 2014). "Photopharmacology: Beyond Proof of Principle" (PDF). J. Am. Chem. Soc. 136 (6): 2178–2191. doi:10.1021/ja413063e. PMID 24456115.
Individual S-acylated cysteines differentially contribute to H-Ras endomembrane trafficking and acylation/deacylation cycles.
Pedro MP1, Vilcaes AA1, Gomez GA2, Daniotti JL3.
Molecular biology of the cell.Mol Biol Cell.2017 Feb 8. pii: mbc.E16-08-0603. doi: 10.1091/mbc.E16-08-0603. [Epub ahead of print]
S-acylation/deacylation cycles and vesicular transport are critical for an adequate subcellular distribution of S-acylated Ras proteins. H-Ras is dually acylated on cysteines 181 and 184, but it is unknown how these residues individually contribute to H-Ras trafficking. In this study, we characteriz
False-Positive Viability PCR Results: An Association with Microtubes.
Agustí G1, Fittipaldi M2, Codony F3.
Current microbiology.Curr Microbiol.2017 Feb 7. doi: 10.1007/s00284-016-1189-3. [Epub ahead of print]
Currently, one of the most challenged points to expand the use of viability PCR technique is achieving the complete exclusion of dead cells amplification signals, thus avoiding the overestimation of live cells population. Considering that, and based on the hypothesis that DNA may be retained by micr
Reversible Photoactivated Phosphorescence of Gold(I) Arylethynyl Complexes in Aerated DMSO Solutions and Gels.
Wan S1, Lu W1.
Angewandte Chemie (International ed. in English).Angew Chem Int Ed Engl.2017 Feb 6;56(7):1784-1788. doi: 10.1002/anie.201610762. Epub 2017 Jan 12.
Phosphorescence in fluid solutions at ambient temperature is usually quenched by molecular oxygen via energy transfer, and singlet oxygen is concomitantly sensitized. The long-lived phosphorescence of a series of AuI arylethynyl complexes with tunable emission energies in aerated dimethyl sulfoxide
Photoactivation of Molecular Oxygen by an Iron(III) Porphyrin with a Magnesium Aluminum Layered Double Hydroxide for the Aerobic Epoxidation of Cyclohexene
