caa a22 4500 46903842X CHVBK 20180323132802.0 cr unu---uuuuu 170328e19920301xx s 000 0 eng 10.1007/BF00810476 doi (NATIONALLICENCE)springer-10.1007/BF00810476 Deprotonation and protonation of hydroxyphenanthroperylenes [Elektronische Daten] [Heinz Falk, Joachim Meyer, Manfred Oberreiter] Deprotonierung und Protonierung von Hydroxyphenanthroperylenen Summary: Ground and excited state deprotonation and protonationpK a values of hydroxyanthraquinones, hydroxyanthrones, hydroxyphenanthroperylenes, and the natural pigments hypericin and pseudohypericin were determined by means of spectrophotometric titrations and Förster cycle calculations. It was concluded that there is a strong intramolecular excited state proton transfer in the hydroxyanthraquinones and hydroxyanthrones due to a reversion of acidity and basicity of the hydroxyl and carbonyl groups in the excited state. However, in the hydroxyphenanthroperylene and the natural pigment excited states the order of basicity and acidity of these two functional groups remain unchanged. The site of deprotonation in hypericin and pseudohypericin was deduced by comparison between thepK a values of suited model compounds and these pigments to be the hydroxyl group in position 3 or 4, respectively. Springer-Verlag, 1992 Hypericin nationallicence Pseudohypericin nationallicence Hydroxyphenanthroperylenes nationallicence Protonation nationallicence Deprotonation nationallicence Spectrophotometric Titration nationallicence Ground state nationallicence Excited state nationallicence Falk Heinz Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut Meyer Joachim Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut Oberreiter Manfred Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut Monatshefte für Chemie / Chemical Monthly Springer-Verlag 123/3(1992-03-01), 277-284 0026-9247 123:3<277 1992 123 706 https://doi.org/10.1007/BF00810476 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00810476 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Falk Heinz Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut NATIONALLICENCE 700 1- Meyer Joachim Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut NATIONALLICENCE 700 1- Oberreiter Manfred Institut für Chemie, Johannes Kepler Universität Linz, A-4040, Linz, Austria aut NATIONALLICENCE 773 0- Monatshefte für Chemie / Chemical Monthly Springer-Verlag 123/3(1992-03-01), 277-284 0026-9247 123:3<277 1992 123 706 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer