Excited singlet and triplet pK values of xanthone in aqueous solution

1972 ◽  
Vol 68 (0) ◽  
pp. 1053 ◽  
Author(s):  
J. F. Ireland ◽  
P. A. H. Wyatt
Keyword(s):  
Aqueous Solution ◽  
Excited Singlet

Influence of pH on the Absorption and Fluorescence Spectra of 6,7-Dihydroxycoumarin in Aqueous Solution

1982 ◽  
Vol 37 (3) ◽  
pp. 262-265 ◽  
Author(s):  
Jerzy Grzywacz ◽  
Stanisława Taszner
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Ph Value ◽  
Emission Spectra ◽  
Excited Singlet ◽  
Acid Base ◽  
Wide Ph Range ◽  
Ph Range ◽  
Influence Of Ph

Abstract Absorption and emission spectra of 6,7-dihydroxycoumarin [6,7-DHC] in aqueous solution over a wide pH range are reported. The absorption spectra proved to be strongly sensitive to the pH-value of the solution, whereas the emission spectra change in this range only insignificantly. An interpretation is attempted on the basis of the differences of the acid-base properties of the 6,7-DHC molecule in its ground and excited singlet state. For this purpose the pKa's and pKax's values have been calculated. It has been stated that in the excited state the phototautomer form is very unlikely.

The Photoreactions of Thymine with Hypoxanthine and Imidazole

1985 ◽  
Vol 40 (1) ◽  
pp. 108-114 ◽  
Author(s):  
Grażyna Wenska
Keyword(s):  
Aqueous Solution ◽  
Photochemical Reactions ◽  
Cycloaddition Reactions ◽  
Excited Singlet

Photochemical reactions of thymine linked to hypoxanthine or imidazole by a trimethylene chain were studied in aqueous solution. Irradiation (λ = 254 nm) of thymine-hypoxanthine pair yielded two internal cycloadducts with azetidine and cyclobutane part structures. Sensitization and quenching experiments suggested that the excited singlet was the reactive state in the photo-cycloaddition reactions. Only cyclobutanes were isolated from irradiated (λ = 290 nm) solutions of thymine-imidazole pairs. Photocycloadditions were reversible upon irradiation at λ = 254 nm

Quenching in the excited singlet state of amphiphilic copolymers with pendant carbazolylalkyl groups in aqueous solution

Polymer ◽  
1996 ◽  
Vol 37 (24) ◽  
pp. 5433-5437 ◽  
Author(s):  
Yoshihiro Itoh ◽  
Tadao Yasue ◽  
Makoto Gouki ◽  
Akira Hachimori
Keyword(s):  
Aqueous Solution ◽  
Singlet State ◽  
Excited Singlet State ◽  
Amphiphilic Copolymers ◽  
Excited Singlet

Der Konzentrationsumschlag der Fluoreszenz aromatischer Kohlenwasserstoffe in mizell-kolloidaler Lösung

1964 ◽  
Vol 19 (1) ◽  
pp. 38-41 ◽  
Author(s):  
Th. Förster ◽  
B. Selinger
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
Excited Singlet ◽  
Concentration Effects ◽  
Dimer Formation ◽  
Singlet States ◽  
Low Concentrations ◽  
Excited Singlet States ◽  
Methyl Naphthalene ◽  
Monomer Fluorescence

Concentration effects in fluorescence spectra, resulting from transient dimer formation in excited singlet states, have been studied in the presence of a detergent in aqueous solution. 2-methyl-naphthalene and pyrene have been used as fluorescers, and cetyl-dimethyl-benzylammonium-chloride as the detergent. The intensity ratio of dimer to monomer fluorescence components has been measured for dilution of the fluorescer alone and also of fluorescer and detergent. The results show that with 2-methyl-naphthalene transient dimer formation depends on the fluorescer concentration within the micelles. With pyrene, where dimer formation occurs at very low concentrations, it seems to depend on the number of single fluorescer molecules per micelle.

Sign in / Sign up

Export Citation Format

Share Document