High "intrinsic" first hyperpolarizability by modulating the conjugation path between donor and acceptor

Summary form only given. The authors report on a series of chromophores that have been synthesized with a modulated conjugation path between donor and acceptor. Hyper-Rayleigh scattering measurements of the best molecules show an enhanced hyperpolarizability that breaches the apparent limit. They show the molecular structures and a plot of the static first hyperpolarizability normalized to the fundamental limit of the hyperpolarizability. It is clear that for the first time, the "Kuzyk gap" is breached. While our best measured values of the hyperpolarizability are still more than an order of magnitude from the fundamental limit, our design strategy appears to be a promising new paradigm for making better molecular materials for electro-optical modulation.