Stilbene Cyclodextrin Derivatives

Figure 21 (a) Chemical structures and schematic representations of photoswitchable stilbene bi-p-cyclodextrin derivative 37 and bi-Ad guest 38. 

Photoisomerization of azobenzenes has been widely developed as photochromic compounds. Lots of papers sriU appeared in this subject from basic chemisty to applications. Some examples were described. Harada et al., reported the effect of cyclodextrin derivatives bearing photo-isomerized stilbene moiety. Single molecule conductance of E- and Z-4, 4 -(ethane-l,2-diyl)dibenzoic acids (E-l and Z-1) was determined using scanning tunnelling microscopy (STM). The dynamics of photoisomerization of E- and Z-urocanic acids (E- and Z-2) driven by Hg-free... 

Wenz et al. have demonstrated that photoreactions are effective for the construction of polyrotaxanes (Scheme 18) [114]. In the knowledge that stil-benes undergo [2+2]photocycloaddition to yield cyclobutane derivatives by UV irradiation, they prepared a quaternary polymeric inclusion complex from /1-cyclodextrin, y-cyclodextrin, (E)-4,4-bis(dimethylaminomethyl)stil-bene (B), and (li)-stilbene polymer (A). Upon irradiation at 312 nm, the (E)-stilbene units of A underwent [2+2]photocycloaddition with B by catalysis of y-cyclodextrin to form the tetraphenylcyclobutane group, which acted as blocking group for /1-cyclodextrin. Wenz et al. claimed that this was the... 

Lewis and his co-workers have continued their investigations into DNA hairpins with a variety of stilbene diether linkages. In the present report they have examined systems based on the linkers (3) and (4). The rotaxane formed between the stilbene derivative (5) and a-cyclodextrin (CD) does not undergo ,Z-isomerization. Contrary to this the complex of (6) with the p-CD isomerizes slowly on irradiation. The behaviour of the stilbene (6) is different and irradiation in a-CD brings about isomerization with a quantum yield of 0.06 for the E,Z process. The quantum yield for the reverse isomerization is 0.71. These values are to be compared with 0.17 and 0.79 for the isomerization in solution. The authors suggest that the irradiation of (6) in the CD brings about a movement... 

Figure 3.8 Changes to the outcome of photolysis of a stilbene derivative through complexation with either / - or y-cyclodextrin ...

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