Bridging photoresponsive

Shinkai et al.111-151 synthesized a series of azobis(benzocrown ethers) called butterfly crown ethers , of which compounds 9 and 10 are examples. Their photoresponsive molecular motion resembles that of a flying butterfly. It was found that the proportion of their Z forms at the photostationary state increases remarkably with increasing concentration of Rb+ and Cs+, which interact with two crown rings in a 1 2 sandwich fashion. This is clearly due to the bridge effect of the metal cations with the two crowns, results that support the view that the Z forms make an intramolecular 1 2 complex with these metal cations. As expected, the Z forms extracted alkali metal cations with large ion radii more efficiently than did the corresponding E forms. In particular, the photoirradiation effect on 9 is quite remarkable for example, ( )-9 (n= 2) extracts Na+ 5.6 times more efficiently than (Z)-9 (n= 2), whereas (Z)-9(n= 2) extracts K+ 42.5 times more efficiently than ( )-9(n= 2). l ... 

Jukes RTF, Adamo V, Hartla F, Belser P, De Cola L. Electronic energy transfer in a dinu-clear Ru/Os complex containing a photoresponsive dithienylethene derivative as bridging ligand. Coord Chem Rev 2005 249 1327-35. 

Electronic energy transfer in a dinuclear Ru/Os complex containing a photoresponsive dithienylethene derivative as bridging ligand 05CCR(249)1327. 

Besson E, Mehdi A, Lerner DA, Reye C, Corriu RJP. 2005. Photoresponsive ordered hybrid materials containing a bridged azobenzene group. J Mater Chem 15 803 809. 

Supramolecular spherical assemblies of NPs with photoresponsive adhesion/dispersal behaviour were also obtained in a ternary system hierarchically combining the host-guest interaction of different types of CDs toward porphyrin and azobenzene. The inclusion complexation of an azobenzene modified water soluble porphyrin (1) with phthalo-cyanine-grafted permethyl (3-CDs (2) could be reversibly cross-linked to relatively larger nanospheres with naphthyl bridged bis(a-CD)s (3). The large spheres (12 -3) turned reversibly to small-sized particles (1 2) upon photoisomerization of the azoaromatic group in 1 (Fig. 13). 

The bridging ligand can also influence the photoresponse via its size. For this purpose tz, dib, pyz and bpy linked iron and rutheniuin complexes were... 

W. Huang, G. Masuda, S. Maeda, H. Tanaka and T. Ogawa, Molecular junctions composed of oUgothiophene dithiol-bridged gold nanoparticles exhibiting photoresponsive properties, Chem. Ear. J., 12, 607-619 (2006). 

Shinkai, S., Kouno, T., Kusano, Y, and Manabe, O., Photoresponsive crown ethers. 7. Proton and metal ion catalyses in the cis-trans isomerization of azopyridines and an azopyridine-bridged cryptand./. Chem. Soc., Perkin Trans. I, 2741, 1982. 

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