A new class of conjugated molecules with large second order polarizability

We report measurements of the second order polarizability β in a new class of conjugated molecules. A representative member of this class is H₃C-NC₅H₄-CH-CH-C₆H₄-O. The measured value of β, 10^-27 esu, for this molecule is larger than any other known value for molecules with the same length and number of π-electrons. We present a discussion of this high value in terms of resonating chemical structures and hyperconjugation.