Abstract

Recently special attention was addressed towards the supramolecular approach to organic electronics, photonics and nanotechnologies [1-3]. The supramolecular chemistry made possible to create architectures at different length scales that provided access to increasing complex functionalities. The possibility to manipulate the local molecular environment provides unique advantages for building a new generation of materials science technologies. Controlling the physico-chemical properties of the supramolecular structures is a fundamental aspect for tuning the materials properties. This control can be performed not only by means of the supramolecular chemistry but also via external stimuli when proper functionalities are present in the materials. One intriguing possibility is to exploit the light [4-5]. Here we present the experimental evidence of the supramolecular chiral structures induced in an absorbing medium, namely a non-chiral azo copolymer, by means of the irradiation with circularly polarized light [6]. The polymeric film undergoes a light-induced inhomogeneous modification of its supramolecular organization, both in the transverse and longitudinal directions. The new structure shows optical activity and influences the propagating light beam, determining a polarization conversion from circular toward linear. The optical activity sign can be controlled by the handedness of the inducing circularly polarized light. The observed supramolecular chiral structures, of both circular and spiral shape, exhibit long time stability and complete reconfigurability, paving a new route to light-by-light polarization control and show the interesting possibility to manipulate the light polarization.

© 2009 IEEE