PROTONATION AND SOLVENT-INTERACTION EFFECTS ON THE FIRST HYPERPOLARIZABILITY OF 2-AMINO-5-NITROPYRIDINE

The protonation effect on the first hyperpolarizability beta of 2-amin o-5-nitropyridine (2A5NP) is examined by Hyper-Rayleigh Scattering (HR S). Using the HRS technique, the beta value of the protonated 2A5NP in acetone is determined to be 22.5 x 10(-30) esu, small in comparison t o the value for the neutral form. The measurement is repeated in 1,4-d ioxane and methanol solutions to examine the influence of the solvent on beta. beta depends on the reaction field, which is written as a fun ction of the dielectric constant of the solvent, the variation of beta in methanol is inconsistent. From this, it is deduced that the first hyperpolarizability of 2A5NP decreases more significantly by hydrogen bond solvent interactions than by protonation. (C) 1997 Elsevier Scien ce B.V.