AM1/CI study of the first-order hyperpolarizability for push–pull quinones and push–pull polyenes A two-level model evaluation

A set of quinone derivatives with di†erent donor and acceptor groups is obtained. The Ðrst-order hyperpolarizabilities (b) are determined by using the two-level model at the level of AM1/CI. The transition moment the dipole moment di†erence (*k) (kge), between the ground and excited states and the maximum absorption wavelength are calculated. The inNuence of the (jmax) strength of the donorEacceptor pairs upon these crucial two-level parameters is investigated with respect to the electronic features. The relationship between these parameters and the Ðrst-order hyperpolarizability is discussed. For comparison, the results for pushEpull hexatriene, another p-conjugated system, are also discussed.