Supramolecular nonlinearity of chromophore-functionalized poly-L-tyrosine

Nonlinear optical chromophores can be organized as orientationally correlat ed side groups of polypeptides with a rigid backbone. In such an organizati on, each chromophore contributes coherently to the second-order nonlinear r esponse of the polymer structure. The synthesis of poly-l-tyrosine, functio nalized with the NLO-phores 4-nitroaniline, 2,4-dinitroaniline, 2-cyano-4-n itroaniline and 4-nitro-4'-nitroazobenzene, which is organized in alpha-hel ix conformation are presented. Solvatochromic measurements show that the hy perpolarizability of the supramolecular structure is a module factor of 18. 7 higher than that of the model chromophore and that conformational organiz ation leads to a strong enhancement of the molecular hyperpolarizability be ta.