Photoresponsive optically active polymers—a review

Photoresponsive macromolecules are of interest both as novel organic materials for applications in photodevices and as models for photomodulated biological processes. The presence in polymer chains of photosensitive groups and of chiral groups capable of inducing optical activity into the polymer is very useful for the analysis of photomodulated structural variations and allows storage of the light effect in the form of chiral information. Polypeptides bearing photochromic groups in the side chains are very convenient as the chiroptical properties of the peptide chromophore can be correlated to the backbone conformation. Thus polymers of L‐aspartic acid, L‐glutamic acid and L‐lysine with azobenzene or stilbene groups attached covalently to the side chains are discussed in terms of photoinduced conformational changes and chiroptical information storage in the spectral region of the peptide and of the photoresponsive chromophore. Optically active photochromic macromolecules with hydrocarbon backbone, such as copolymers of (—)‐menthyl acrylate with vinyl or acryloyl derivatives of azobenzene, stilbene and indolinospirobenzopyran, also show in some cases photodependence of chiroptical properties with evidence of at least local conformational changes as a consequence of light irradiation which can be used for chiral information.