Neue Dimethinmerocyaninfarbstoffe mit J-Aggregation in stark verdünnter Lösung

Novel Dimethinmerocyanine Dyes Performing J-Aggregation in Highly Diluted Solution A series of various novel long-chain alkyl-dimethinmerocyanine dyes containing sulfonate groups is obtained in high yield by modified condensation reactions of sulfoalkyl- or sulfophenylsubstituted methylene ketones. The dyes exhibit intense, red-shifted absorption bands (? up to 263 000) due to J-aggregation in DMSO/H₂O mixtures without addition of salt even at dye concentrations of 5 · 10^?8M. The influence of dye structure and medium on the aggregation tendency is investigated. Besides it is found that exchange of the cationic counterions does not affect J-aggregation.     

Diffusionsverteilung des stark ionisierten Gemisches von Argon mit Stickstoff

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Die Trennung der Platinmetalle mit Hilfe stark basischer Anionenaustauscher

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Die Bestimmung des Nitratgehaltes in Salpetern mit Hilfe stark saurer Kationenaustauscher

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Trennung kleiner Mengen Gallium von Eisen mit einem stark basischen Anionenaustauscher

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Zur Photochemie von 1, 2-Benzisoxazolen in stark saurer Lösung

On the Photochemistry of 1, 2-Benzisoxazoles in Strongly Acidic Solution The 1, 2-benzisoxazoles 1a, 1b and 1d when dissolved in 96% sulfuric acid and irradiated through a quartz filter with a mercury high-presure lamp yield, after work-up, mixtures of 2, 5- and 2, 3-dihydroxy-acylbenzenes ( 2 and 3 , respectively; cf. Schemes 1 and 3 and Table 1). Irradiation of 3, 5-dimethyl-1, 2-benzisoxazole ( 1c ) in 96% sulfuric acid leads to the formation of 2, 3-dihydroxy-5-methyl-acetophenone ( 3c ) in only 6% yield (cf. Table 1). It is assumed that the 1, 2-benzisoxazolium ions react in the excited singlet state by heterolytic cleavage of the N, O-bond to yield the corresponding aryl oxenium ions 7 in the singlet ground state (see Scheme 5). Reaction of 7 with HSO ₄ ? ions, present in 96% sulfuric acid, yields, after hydrolysis, the dihydroxy compounds 2 and 3 . Photolysis of 3-methyl-1, 2-benzisoxazole ( 1b ) in diluted sulfuric acid (0,5 to 9 M ) in methanol or water leads only to the formation of 2-amino-phenol ( 6 ; see Scheme 3), presumable via photo-isomerization of 1b to 2-methylbenzoxazole ( 5b ) which then is hydrolyzed to give 6 .