Optical acitivity and photochromism of the azo chromophore bound to poly(L‐glutamic acid)

Optical Activity and Photochromism of the Azo Chromophore Bound to Poly(L-Glutamic Acid)The introduction of photochromic moieties into polymer chains can produce variations of conformational properties induced by light, such as those which occur in several photoregulated biological systems.'For instance photochromic azo dye^^-^ and ~piropyrans,6*~ either covalently or noncovalently connected to macromolecules, have been used to obtain photoregulation in membranes7 and to control polymer c ~n f o r m a t i o n .~. ~. ~ Goodman and coworker^^^^ investigated polypeptides containing residues from L-p-(pheny1azo)-phenylalanine by ORD measurements, and attributed the observed transformation of the spectra, on irradiation, to the transcis photoisomerization of the azoaromatic