VOLTAGE-SENSITIVE FLUORESCENCE OF AMPHIPHILIC HEMICYANINE DYES IN A BLACK LIPID-MEMBRANE OF GLYCEROL MONOOLEATE

Amphiphilic fluorescent hemicyanine dyes were adsorbed to a hemispheri cal bimolecular membrane of glycerol monooleate. Their excitation spec tra of fluorescence were as in water, their emission spectra were as i n hydrocarbon. An AC-voltage was applied across the membrane and the r elative changes of the spectra of excitation and of emission were reco rded. For all dyes we observed a blue-shift of excitation with positiv e voltage on the opposite side of staining. The effect is compared wit h the blue-shift expected for electrochromism. For most dyes we observ ed a red-shift of emission and a drop of the fluorescence intensity. T hese effects are compared with the red-shift and the drop of quantum y ield expected for a voltage-induced solvatochromism caused by a minute displacement of the dyes in the anisotropic environment at the membra ne/water interface.