Recognition azobenzene

Kikuchi, T. Narita, M. and Hamada, F. (2002) Synthesis of bis dansyl-modified /f-cyclodextrin dimer linked with azobenzene and its fluorescent molecular recognition, J. Incl. Phenom. 44, 329-333. 

Photoresponsive host-guest systems based on azobenzene-substituted crown ethers have been shown to be particularly effective in the control of molecular recognition by light, due to their large geometrical changes upon E-Z isomerization. 55 A num-... 

The E-Z isomerization of an azobenzene unit was employed in an approach towards photocontrol of the chiral recognition event in a membrane.1581 To this end, (4-(phenyl-azo)phenyl carbamate residues were attached to carbamate-protected glucose units of cellulose and amylose. The photomodulation of the chiral recognition was explained by a change in the ordering of the polymer, leading to a change in solubility. 

Figure 15.6 Schematic diagram of the azobenzene nanotube assembly on the complementary a-CD/Au substrates via host-guest molecular recognition and light-induced nanotube detachment and attachment on the a-CD surfaces.20 (Reprinted with permission from I. A. Baneijee et al., J. Am. Chem. Soc. 2003,125, 9542-9543. Copyright 2003 American Chemical Society.)...

Photochemical switches are also discussed in Special Topic 6.15 (Scheme 6.161) and Special Topic 6.19 (Scheme 6.207). Here we illustrate the photoswitching process, which can control the geometry of biomolecules.1101 When an azobenzene-derived cross-linker in the DNA-recognition helix of the transcriptional activator MyoD is irradiated at 360 nm, the linker predominantly attains a Z-configuration that significantly stabilizes the helix (Scheme 6.193).1209 Reverse isomerization can proceed either thermally or photochemically at a different wavelength therefore, the process is photochromic (Special Topic 6.15). 

Minoura N, et al. 2004. Preparation of azobenzene containing polymer membranes that function in photoregulated molecular recognition. Macromolecules 37(25) 9571 9576. 

Supramolecular chemistry typically involves the complexes based on molecular recognition, which include crown ethers, catenates, rotaxanes, etc. Azobenzene derivatives are often used as structural elements in such supramolecular assembly. Already in 1980 (Shinkai et ah, 1980), azobenzene moiety had been introduced into crown ether. Other recent examples include azobenzene-cyclodextrin complexes (Callari et ah, 2006), azobenzene-attached nanotube-cyclodextrin complexes (Descalzo et al., 2006), and molecular recognition complexes with DNA (Haruta et al., 2008). Numerous examples of photoswitch-able azobenzene supramolecular systems in solutions can be found (Yagai et al., 2005 Balzani et al., 2002). But there are no investigations in these systems concerning photoorientation and mass transport. 

Haruta O, Matsuo Y, Hashimoto Y, Niikura K, Ijiro K. 2008. Sequence specific control of azobenzene assemblies by molecular recognition of DNA. Langmuir 24 2618 2625. 

X. Chen, et al., Photo-controlled molecular recognition of a-cyclodextrin with azobenzene containing polydiacetylene vesicles, Chem. Commun. 11 (2009) 1356-1358. 

Cudic P, Vigneron J-P, Lehn J-M, Cesario M, Prange T. Molecular recognition of azobenzene dicarboxylates by acridine-based receptor molecules crystal structure of the supramolecular inclusion complex of trans-3,3 -azobenzene dicarboxylate with a cyclo-bis-intercaland receptor. Eur J Org Chem. 1999 1999 2479-2484. 

In a complex based on two a-CDs derivatized at the secondary rim with a molecular chain bearing two recognition sites, a photoresponsive azobenzene unit elose to the rim and a non-photoresponsive hepta-methylene (Cy) moiety connected by an oligoethylene glycol linker, a... 

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