Photobiological switches

Recent research efforts have been directed towards the development of semisynthetic photobiological switches11,21. An artificial biological photochemical switch is defined as a biological material or environment that is chemically functionalized by photoresponsive units, enabling the photonic activation of the innate functions of the respective biological matrices. Within this broad definition one may define two subclasses of photobiological switches ... 

Harvey AJ, Abell AD. 2001. a Ketoester based photobiological switches synthesis, peptide chain extension and assay against a chymotrypsin. Bioorg Med Chem Lett 11(18) 2441 2444. 

Harvey AJ, Abell AD. Azobenzene-containing, peptidyl alfa-ketoesters as photobiologi-cal switches of alfa-chymotrypsin. Tetrahedron 2000 59 9763-71. 

Photochemical cis-trans isomerization is a major area of interest in modem photochemical research and is also studied as part of organic photochemistry. Photochemical cis-trans isomerization has a major role in many photobiological phenomena, such as vision (rhodopsin) [1], ATP synthesis (bacteriorhodopsin) [2], phototaxis (Chlamydomonas) [3], and other allied processes. It has practical application in industry [4-6], i.e., vitamin A and D processes. Furthermore, it is a likely candidate for many optoelectrical and optomechanical switching and storage devices [7]. In this chapter, mainly various aspects of cis-trans isomerization originating from the singlet excited state will be discussed. 

Petracchi, D., Lucia, S., and Cercignani, G. (1994) New trends in photobiology photobehaviour of Halobacterium halobium proposed models for signal transduction and motor switching. /. Photochem. Photobiol. B Biol. 24, 75-99. 

Several reviews have been published within the year which are of general relevance to the photoreactions of aromatic compounds. The subjects of these reviews include photochemistry in ionic liquids and in isotropic and anisotropic media, organic synthesis utilizing photoinduced electron-transfer reactions," heteroatom-directed photoarylation processes, photochromism, and photochemical molecular devices. Reviews more directly pertinent to the sections in the present chapter include those of the photoisomerization of five-membered heteroaromatic azoles, the photocycloaddition of benzene derivatives to alkenes, Diels-Alder additions of anthracenes, advances in the synthesis of polycyclic aromatic compounds, diarylethene-based photochromic switches, the photo-Fries rearrangement, and the application of Diels-Alder trapping of photogenerated o-xylenols to the synthesis of novel compounds. " A number of chapters in the two recently published handbooks of photochemistry and photobiology and in the revised edition of the text on photochromism are also pertinent to the current subject matter. 

Yager KG, Barrett CJ. 2006a. Novel photo switching using azobenzene functional materials. J Photochemistry Photobiology A Chemistry 182(3) 250 261. 

Scheme 15 Schematic of the gold nanoparticle-bound switch. Journal of Photochemistry and Photobiology A Chemistry, Vol. 221, H. Nishi, T. Asahi and S. Kobatake. Enhanced photocycloreversion reaction of diarylethene polymers attached to gold nanoparticles in the solid state, pages no. 256-260. Copyright (2011), with permission from Elsevier. 

Hong, ET, Molecular electronic switches in photobiology, in Handbook of Organic Photochemistry and Photobiology, 1st ed., Horspool,W. and Song, P.-S., Eds., CRC Press, Boca Raton, FL, 1995, p. 1557. 

Molecular Switching Processes in Major Photobiological Systems... 

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