Second-order polarizability of p-substituted cinnamic acids

First-order hyperpolarizabilities (β) of a series of p-substituted cinnamic acids have been measured using the hyper-Rayleigh scattering technique and compared with those of p-substituted benzoic acids. β in these acids increases as a function of the donor strength. It increases twice with the increase in the effective chain length. Semi-empirical calculations also support this enhancement. Solvents effects are dealt with at the ab initio level within the self-consistent reaction field approach.