Microhydration and the Enhanced Acidity of Free Radicals

John Walton
2018 Molecules  
Recent theoretical research employing a continuum solvent model predicted that radical centers would enhance the acidity (RED-shift) of certain proton-donor molecules. Microhydration studies employing a DFT method are reported here with the aim of establishing the effect of the solvent micro-structure on the acidity of radicals with and without RED-shifts. Microhydration cluster structures were obtained for carboxyl, carboxy-ethynyl, carboxy-methyl, and hydroperoxyl radicals. The numbers of
more » ... The numbers of water molecules needed to induce spontaneous ionization were determined. The hydration clusters formed primarily round the CO 2 units of the carboxylate-containing radicals. Only 4 or 5 water molecules were needed to induce ionization of carboxyl and carboxy-ethynyl radicals, thus corroborating their large RED-shifts.
doi:10.3390/molecules23020423 pmid:29443952 fatcat:nbqkjvciqra2tjs75f5ynkyfvq