AN INTRAMOLECULAR HYDROGEN-BONDED SYSTEM WITH LARGE PROTON POLARIZABILITY - A MODEL WITH REGARD TO THE PROTON PATHWAY IN BACTERIORHODOPSIN AND OTHER SYSTEMS WITH COLLECTIVE PROTON MOTION

3-Diethylaminomethyl-2,2'-biphenol was synthesized and studied by FT-IR and H-1 NMR spectroscopy. The compound forms a system with two hydrogen bonds which shows large proton polarizability due to collective proton motion. This result supports our earlier suggestion that the first part of the proton pathway in bacteriorhodopsin conducting protons is a hydrogen-bonded chain with large proton polarizability built up by arginine and tyrosine residues. Furthermore, we show that in the monotetrachloroaurate of 3,3'-bis(diethylaminomethyl)-2,2'-biphenol and in the tritetrachloroaurates of 3,3',5,5'-tetrakis(diethylaminomethyl)-2,2'-biphenol there is proton polarizability due to collective proton motion.