Biomaterial Database

Excited-state proton transfer of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid. 2010

D Vulpius, and G Geipel, and G Bernhard

Forschungszentrum Dresden-Rossendorf e V, Institute of Radiochemistry, PO Box 510119, 01314 Dresden, Germany. d.vulpius@fzd.de

The excited-state proton transfer of 3-hydroxybenzoic acid and 4-hydroxybenzoic acid was studied by time-resolved laser-induced fluorescence spectroscopy with ultra-short laser pulses. The excited-state reactions were identified in aqueous media as a function of the pH value. Apart from the well-known inversion of the ordinary dissociation properties of these compounds, new species were found which exist only in the excited-state resulting from a temporal and reversible annihilation of the aromatic bond system. These species and their reaction mechanisms were detected by their absorption and fluorescence spectra.

UI	MeSH Term	Description	Entries
D010226	Parabens	Methyl, propyl, butyl, and ethyl esters of p-hydroxybenzoic acid. They have been approved by the FDA as antimicrobial agents for foods and pharmaceuticals. (From Hawley's Condensed Chemical Dictionary, 11th ed, p872)	4-Hydroxybenzoic Acids,Paraben,para-Hydroxybenzoic Acids,4 Hydroxybenzoic Acids,para Hydroxybenzoic Acids
D011522	Protons	Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.	Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D062385	Hydroxybenzoates	Benzoate derivatives substituted by one or more hydroxy groups in any position on the benzene ring.	Hydroxybenzoic Acids,Acids, Hydroxybenzoic