Approaches for optimizing the first electronic hyperpolarizability of conjugated organic molecules.

A two-state, four-orbital, independent electron analysis of the first optical molecular hyperpolarizability, beta, leads to the prediction that |beta| maximizes at a combination of donor and acceptor strengths for a given conjugated bridge. Molecular design strategies that focus on the energetic manipulations of the bridge states are proposed for the optimization of beta. The limitations of molecular classes based on common bridge structures are highlighted and more promising candidates are described. Experimental results supporting the validity of this approach are presented.