Ground and excited state dipole moments of all-t r a n s-retinal and all-t r a n s-retinylidene-n-butylamine in solution

Ground state dipole moments of all-trans-retinal and all-trans-retinylidene–n-butylamine have been determined by dielectric constant measurements of dilute hexane solutions. Excited state dipole moments for the intense low energy absorption band have been estimated from the ground state moments and an analysis of the solvent shifts of absorption spectra using a corrected solvent shift theory. The ground state moments of all-trans-retinal and the n-butylamine Schiff’s base were found to be 4.6 and 2.1 D, respectively. The corresponding excited state moments are approximately 6 and 5 D.