Solvents effects on molecular first-Hyperpolarizabilities of stilbazolium-like dyes

We have proved that the first - hyperpolarizabilities (beta(chi chi chi)) o f the four stilbazolium - like dyes, which are trans - (N - methylpyrrol - 2 - yl) - 4 - (N - methyl - pyridinio) - stilbazolium iodide (MPPSI), trans - (pyrrol - 2 - yl) - 4 - (N - methyl - pyridinio) - stilbazolium iodide ( PPSI), trans - (furan - 2 yl) - 4 - (N - methyl - pyridinio) - stilbazolium iodide (FPSI) and trans - (thiophene - 2 - yl) - 4 - (N methyl- pyridinio) - stilbazolium iodide (TPSI), can be linearly correlated with the electron excessivities of donors in fifteen solvents. Then we obtained the linearit y correlation between the beta(chi chi chi) Of the dyes and the solvents po larity [ E-T(30)]. From the two linearity correlations we obtain three solv ent factors eta, delta(A) and delta(D) for describing the solvents effects on the beta(chi chi chi): eta describes the sensitivity of the intramolecul ar electron transfer to the solvent polarity, delta(A) and delta(D) describ e the accepting/donating ability of the acceptor/donor effected by the solv ent polarity respectively. The delta(A) increases linearly, but the delta(D ) is decreased linearly with increasing of the E-T(30).