MEROCYANINE DYE - AN AGENT FOR TRANSMEMBRANE PROTON TRANSFER

S. Das, R. Basu, S. De, M. J. Minch* and P. Nandy

Physics Department, Jadavpur University, Calcutta - 700032, INDIA *Chemistry Department, University Pacific, California 95211, USA

Merocyanine derivative dyes can undergo heat/light induced trans to cis isomerisation (1). When incorporated in lipid membranes, separating two asymmetric bathing solutions, due to their iso- merisation property, the dyes can transport H⁺ ions from one side of the membrane to the other. This, in turn, gives rise to a transmembrane potential difference.

We have utilised this proton gate mechanism of several merocyanine derivative dyes sucessfully in devising solar storage cell. Here the dye has been incorporated in organised assembly of oxidised cholesterol which forms a membrane seperating two bathing solutions: one containing iodine/iodide (side A) whereas the other contains HCl (side B). The heat/photo induced voltage generated due to transfer of proton from side B to side A can be measured by means of a pair of platinum electrodes placed symmetrically across the memebrane. The voltage thus generated can be stored for hours due to the vectorial proton transport mechanism, comparatively low mobility of protons and the high electrical resistance of the organised lipid assembly, which prevents back recombination.