Excited-state proton transfer from pyranine to acetate in methanol

Abstract

Excited-state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6- trisulphonate, HPTS) to acetate in methanol has been studied by steady-state and time-resolved fluorescence spectroscopy. The rate constant of direct proton transfer from pyranine to acetate, (k1) is calculated to be ∼1 × 109 M-1 s-1. This is slower by about two orders of magnitude than that in bulk water (8 × 1010 M-1 s-1) at 4 M acetate. © Indian Academy of Sciences.