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Über das «p K » elektronisch angeregter Azulenium‐Kationen
Author(s) -
Hagen R.,
Heilbronner E.,
Meier W.,
Seiler P.
Publication year - 1967
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19670500611
Subject(s) - chemistry , excited state , azulene , ground state , quenching (fluorescence) , fluorescence , medicinal chemistry , stereochemistry , photochemistry , atomic physics , physics , quantum mechanics
It is shown that azulenium cations in the first electronically excited state S 1 are stronger acids than in the ground state S 0 . Their apparent p K ″*, obtained from the H 0 ‐dependence of the quenching of the azulenium cation S 1 → S 0 fluorescence does not correspond to a true acid‐base equilibrium in the electronically excited state S 1 . The p K ″* values are kinetically controlled, the rate of reprotonation of azulene in the S 1 state being too low to compete with the internal conversion to S 0 .