Proton transfer reaction of 4-hydroxy-1-naphthalenesulphonate in methanol-water and ethanol-water mixtures

The excited state proton transfer rate of 4-hydroxy-1-naphthalenesulphonate has been studied in methanol-water and ethanol-water mixtures. The lifetimes of the probe are measured at six different temperatures between 5 and 60°C. The decay is single exponential in the long time regime and proton transfer rates have been found to increase with the square of the concentration of water in alcohol-water mixtures. The decay has been explained by a new model proposing a water dimer to be the effective proton acceptor in the proton transfer process.