Push-pull biphenyl compounds appear to be model systems for studying the la
rge sensitivity to the dielectric environment of zwitterionic molecules. We
present here a systematic theoretical and experimental study, combining nu
merical simulations and NMR, IR and NLO measurements on two analogous diary
l molecules dissolved in solvents with varying polarities. (C) 2001 Elsevie
r Science B.V. All rights reserved.