From molecular to supramolecular engineering in nonlinear optics: mixed carotenoid-cyclodextrin Langmuir-Blodgett films

Several push-pull polyenes and carotenoids have recently been found to display efficient optical second harmonic generation (SHG) in both the solid state and solution.1,2 However, their rigid elongated structure limits the possibility of further organization of these moieties into conventional structures such as single crystals or Langmuir-Blodgett (LB) films. We propose here an original supramolecular approach to circumvent these problems by means of inclusion of the polyene guest in functionalized cyclodextrins. We furthermore demonstrate a way to pile up multilayers of such host-guest systems in a noncentrosymmetric structure displaying a high quadratic nonlinear optical response.