" NEW APPROACHES FOR INTERESTING PRECURSORES IN THE HETEROCYCLIC AND CYANINE DYES SYNTHESIS "
Samia Mohamed Sayed;
Abstract
Synthesis of new oxazoles (Sa-c, 12a-c), pyrazolo [1,5-a] pyrimidine (16) triazolo [1,5-a] pyrimidine (23) and thiazolo [1,5-a] pyrimidine (29). Synthesis of new azol-2-yl thiophenes (37, 43a-c, 45a-c, 47, 48 and SOa-c) and azolyl pyridazines. The new synthesised compounds were identified by elemental analysis, lR and 1H-NMR.
Key words: Oxazoline-5-one; Thiazole and Thiadiazole.
Abstract Part ( II )
New asymmetrical imidazo [1,2-b] thiazolium ylide, pyrrolo [1,2-a] quinoline, condensed pyrazole, triazolo and thiazolo [1,5-a] pyrimidine cyanine dyes were prepared. Such dyes covers isoapocyanine (6a-h, 7a,b, Sk-m, 9f-h), monomethine (bismono) (20a-e, 21a-c, 22a-d, 23a-d, 24a,b,
25a-c and 26a,b) and dimethine, mono (di) methine types (lla g, 12, 13). The new synthesised cyanines were identified by elemental analysis and IR, 1H-NMR and Mass spectral data. The UV and visible absorption spectra of some selected dyes were investigated in pure and mixed solvents as well as in
aqueous buffer solutions. Molecular complex formation with ethanol was verified thr'ougll titixed solvent studies. Electronic transitions have been attributed to either locally excited or predominatly charge transfer states. The spectral shifts are discussed in relation to molecular structure and in terms of medium effects. The variation of absorbance with pH is utilized for the determination of the pKa value for a selected dyes (21a,b, 22a,b, 23a,b, 25b and 26b).
Key words: Oxazoline-5-one; Thiazole and Thiadiazole.
Abstract Part ( II )
New asymmetrical imidazo [1,2-b] thiazolium ylide, pyrrolo [1,2-a] quinoline, condensed pyrazole, triazolo and thiazolo [1,5-a] pyrimidine cyanine dyes were prepared. Such dyes covers isoapocyanine (6a-h, 7a,b, Sk-m, 9f-h), monomethine (bismono) (20a-e, 21a-c, 22a-d, 23a-d, 24a,b,
25a-c and 26a,b) and dimethine, mono (di) methine types (lla g, 12, 13). The new synthesised cyanines were identified by elemental analysis and IR, 1H-NMR and Mass spectral data. The UV and visible absorption spectra of some selected dyes were investigated in pure and mixed solvents as well as in
aqueous buffer solutions. Molecular complex formation with ethanol was verified thr'ougll titixed solvent studies. Electronic transitions have been attributed to either locally excited or predominatly charge transfer states. The spectral shifts are discussed in relation to molecular structure and in terms of medium effects. The variation of absorbance with pH is utilized for the determination of the pKa value for a selected dyes (21a,b, 22a,b, 23a,b, 25b and 26b).
Other data
| Title | " NEW APPROACHES FOR INTERESTING PRECURSORES IN THE HETEROCYCLIC AND CYANINE DYES SYNTHESIS " | Other Titles | " طرق جديدة للبادرات الأولية الهامة لاصطناع حلقات غير متجانسة وأصباغ السيانين " | Authors | Samia Mohamed Sayed | Keywords | .Cyanine dyes, synthesis, spectral behaviours, solvatochromic and acido (baso) media chromic behaviours | Issue Date | 1998 |
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