P- phenylazo benzyl

Methyl-1- p -phenylazophenyl) ethyl, 770 p- (p -Methoxyphenylazo) benzyl, 770 p-(Phenylazo) benzyl, 770 2,4,6-Trimethylbenzyl, 770... 

In pioneering articles published in 1966 and 1967, Goodman et al. described a series of polypeptides derived from p-phenylazo-L-phenylalanine and y-benzyl-L-glutamate by polymerization of the corresponding N-carboxy anhydrides (Scheme 2).118,191... 

Scheme 2 Chemical structure of polypeptides containing p-phenylazo-L-phenylalanine and y-benzyl-L-glutamate residues (II).

The exploitation of the ,Z-isomerization of the azoaromatic group for conformational problems was first studied in the 1960s. Goodman and Fabca synthesized copolypeptides of L-p-(phenylazo)phenylalanine with y-benzyl-L-glutamate. They found that photoisomerization of the azobenzene group in synthetic polypeptides resulted in changes in the ORD spectra due to changes in the conformation. 

Large photoresponse effects could be observed in solvent mixtures, provided that the irradiation was carried out at appropriate solvent compositions. A copolypeptide composed of 33 mol% P-benzyl-L-aspartate and 67 mol% para-phenylazo-L-aspartate (X) was found to give different kinds of photoresponse, depending on the composition of the solvent in which irradiation was carried out. In dichloroethane (DCE)/ hexafluoropropanol (HFP) = 95/5, irradiation at 320-390 nm produced an increase in right-handed helix content in DCE/HFP = 54/26, a light-induced conformational change from left-handed helix to random coil was observed while, finally, reversal of the helix sense occurred in DCE/HFP = 65/35.150,511... 

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