Molecular switching in nano-structured photochromic films of biopolymers

This paper reports the investigation of the photochromic and conformational behaviour of a poly (l-glutamic acid) (PSG) chemically modified with 85% spiropyran units in the side chains, PSG. We preliminary studied the behaviour of PSG in solution and then we performed a characterisation of the polymer in bidimensional systems. PSG monolayer at the water–air interface was characterised by means of surface pressure–molecular area isotherms and UV–Vis Spectroscopy and the photochromic behaviour was illustrated. Moreover, we transferred, by means of the Langmuir–Blodgett (LB) technique, polypeptide monolayers onto solid support in order to obtain ordered and nano-organized systems whose spectroscopic properties were investigated.