Valentino, Maria R. published the artcileQuenching behavior of singlet excited 9-arylxanthylium cations, Computed Properties of 596-38-3, the publication is Journal of Organic Chemistry (1993), 58(21), 5826-31, database is CAplus.
Several 9-arylxanthylium tetrafluoroborate salts (Ar = H, p, m-F, p, m-Me, m-OMe) were synthesized by reaction of the corresponding 9-arylxanthen-9-ol with fluoroboric acid. Spectral characteristics of the xanthyl cations were identical to those previously reported for the cations generated by alternate methods. The 9-arylxanthyl cation fluorescence was quenched by the addition of H2O, MeOH, i-PrOH, and t-BuOH. Stern-Volmer anal. of the fluorescence quenching gave bimol. excited-state rate constants ranging from 106 to 1010 M-1 s-1, with the larger rate constants associated with electron-donating substituents. Hammett plots of log[kq(X)/kq(H)] vs. σhv gave neg. ρ values for each quencher, opposite to the substituent dependence observed for ground-state cations reacting with nucleophiles. The relative quenching order also differs from the order observed for ground-state cation reactions. The mechanism for quenching of the singlet excited 9-arylxanthylium cations is evaluated in terms of nucleophilic attack. The possibility of an electron-transfer mechanism is considered and eliminated.
Journal of Organic Chemistry published new progress about 596-38-3. 596-38-3 belongs to alcohols-buliding-blocks, auxiliary class Other Aromatic Heterocyclic,Benzene,Alcohol, name is 9-Phenyl-9H-xanthen-9-ol, and the molecular formula is C6H8BNO3, Computed Properties of 596-38-3.
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