7-Alkoxy coumarins as fluorescence probes for microenvironments

7-Alkoxy and 4-methyl-7-alkoxy coumarins show solvent-dependent fluorescence emission. The monomeric fluorescence emission of these alkoxy coumarins was exploited as a probe to measure the surface polarity of the micelles formed by ionic (sodium dodecylsulphate and cetyltrimethyl-ammonium bromide) and non-ionic (Triton X-100) detergents. By comparing the solvent-dependent fluorescence of these alkoxy coumarins in various homogeneous solvents, the polarity of the micelles was determined qualitatively. All three micelles are more polar than hydrocarbon solvents but are less polar than water

PHOTOFRAGMENTATION REACTIONS OF THIOCARBONYL COMPOUNDS

Brunelle Lucien. Pratique ou praxis pédagogiques faut-il choisir ?. In: Raison présente, n°83, 3e trimestre 1987. Le besoin de psychiatrie. pp. 148-150

ChemInform Abstract: PHOTOFRAGMENTATION REACTIONS OF THIOCARBONYL COMPOUNDS

Unter Bestrahlung erhält man aus dem Cyclobutanonthion (I) die Thioheterocyclen (II) und (III) bzw. (II)‐(IV), wenn man die Photolyse in Methanol durchgeführt

Photolysis of the dithiolactone 4-isopropylidene-3,3-dimethyl-1-thietan-2-thione; a Norrish type I reaction

The dithiolactone (1) upon excitation gives the dithione (2) in cyclohexane and other aprotic solvents and a 1 : 1 adduct in hydroxylic solvents from an n* excited singlet state via an -cleavage process

Photofragmentation Reactions Of Thiocarbonyl Compounds

Preferential yield of ring expansion and rearrangement products through α-cleavage of tetramethyl-3-thio-1,3-cyclobutanedione (1) and 3-mercapto-2,2,4-trimethyl-3-pentenoic acid β-(thio lactone) (2) involving diradical and carbene has been observed upon photolysis of 1 and 2

7 - Alkoxy coumarins as fluorescence probes for microenvironments

7-Alkoxy and 4-methyl-7-alkoxy coumarins show solvent-dependent fluorescence emission. The monomeric fluorescence emission of these alkoxy coumarins was exploited as a probe to measure the surface polarity of the micelles formed by ionic (sodium dodecylsulphate and cetyltrimethyl-ammonium bromide) and non-ionic (Triton X-100) detergents. By comparing the solvent-dependent fluorescence of these alkoxy coumarins in various homogeneous solvents, the polarity of the micelles was determined qualitatively. All three micelles are more polar than hydrocarbon solvents but are less polar than water

Strain-Assisted \alpha-Cleavage Reactions of Thioketones: Cyclobutanethiones

Photochemical \alpha -cleavage from the lowest triplet state $(n\pi^*, T_1)$, resulting in the generation of a diradical intermediate, appears to be general for cyclobutanethiones. The diradical intermediate derived from 1,3-dithione is observed to undergoes ring expansion to carbene or close to either dithione or dithiolactone. The Photochemical behavior reported here for cyclobutanethiones is different from that of the corresponding cyclobutanones. \alpha-Cleavage processes in the case of cyclobutanethiones are not efficient and are often accompanied by side reactions