Azobenzene-sulfonate groups

Analogous membranes have been prepared from poly(L-glutamic acid) containing about 14 mol % azobenzene-sulfonate groups in the side chains (Scheme 3, Structure IV). 25 109 The polypeptide was adsorbed onto a porous support and the hydro-... 

No reaction occurs under these conditions with esters, acid chlorides, acid anhydrides, azobenzene, sulfones, and sulfonyl chlorides. The following groups evolve hydrogen but do not undergo reduction alcohols, phenols, carboxylic acids, amides, and sulfonic acids. Aldehydes and ketones are reduced to alcohols, and N,N-dimethylamides to aldehydes. F. e. s. H. C. Brown and D. B. Big-ley, Am. Soc. 83, 486 (1961). 

More recently, Stevenson (52a) confirmed the existence of weak but specific binding activity in H and L chains of rabbit antibody to the Dnp and 4-azobenzene-1-sulfonate hapten groups. For either type of chain the dimeric but not the monomeric form was active. The author postulated that a pair of identical chains can combine in such a manner as to produce a site with hapten-binding activity. (See also Chapter 5.)... 

The photochemical and photophysical behavior of azobenzene adsorbed on polymer or silica films has been reported recently " azobenzene adsorbed in water-swollen Nafion-H+ (Nafion is a polymer consisting of a perfluorinated backbone and short pendant chains terminated by sulfonic acid groups) exhibited strong fluorescence. The irradiation resulted in the formation of benzo[c]cinnoline and benzidine in quantitative yield, while azobenzene incorporated into a methanol-swollen Nafion-H+ membrane did not emit fluorescence but merely underwent E,Z-isomerization. Thus, solvent-swollen Nafion is useful in the selective phototransformation of azobenzene. According to the authors, protonated azobenzene molecules are located at the fluorocarbon/water interface in water-swollen Nafion-H+ Z-Azobenzene formed on these membranes resulted in cychzation to give the observed products (Scheme 52). 

Another optical switchable [2]rotaxane was also developed in our group [26]. The rotaxane consists of an a-CD ring, an azobenzene unit and two fluoroph-ores — ANS and a naphthalimide sulfonic acid (NS). The cyclodextrin ring can be driven from the azobenzene unit to the biphenyl group by the light irradiation at 360 nm, and the fluorescent intensity of ANS at 520 nm decrease as well as the increasing of NS at 395 nm. The backward process can be obtained reversibly by the irradiation at 430 nm and the fluorescence intensities of the two stoppers are recovered. 

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