Pyrene-1-carboxylate in water and glycerol solutions: origin of the change of pK upon excitation.
Pyrene-1-carboxy acid has a pK of 4 in the ground state, and a pK of 8 in the excited state. Fluorescence spectra of the acid and base forms are presented as a function of solvent and temperature. Ab initio quantum calculations indicate that the bond between the ring system and the carboxyl group has aromatic character that becomes stronger upon excitation. This stabilization helps to account for the increase in pK upon excitation.
Nucci
Nathaniel V
NV
Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Zelent
Bogumil
B
Vanderkooi
Jane M
JM
D002264:Carboxylic Acids / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D015394:Molecular Structure; D011721:Pyrenes / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry*
D002264:Carboxylic Acids; D011721:Pyrenes; D012996:Solutions; D014867:Water; C030984:pyrene; D005990:Glycerol