Electronic Absorption Spectra of New y-Keto-dimethine Cyanine Dyes and ApocyaninesReport as inadecuate




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Croatica Chemica Acta, Vol.63 No.4 March 1991. -

New asymmetrical y-keto-dimethine cyanines 2.-f were prepared through the condensation of phenyl glycosal derivatives l.-e with 2-methyl pyridinium quinolinium- 2yl salts. Such dyes were converted into the corresponding dyes 3a-g and 4a-d by cyclocondensation with hydrazines or hydroxylamine hydrochloride under suitable conditions. The new synthesized cyanines were identified by elemental and spectral analyses. The U-V-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 by mixed solvent studies. Electronic transitions were attributed to either locally excited or predominantly charge

transfer states. The spectral shifts were discussed in relation to molecular structure and in terms of medium effects. The variation of absorbance with pR was utilized for the determination of the pK. value for aselected compound 2e. The photostability of some selected đyes 2e, 3g and 4d was investigated.



Author: A. I. M. Koraiem - ; Chemistry Department, Aswan-Faculty of Science, Aswan, Egypt M. M. Girgis - ; Chemistry Department, Faculty

Source: http://hrcak.srce.hr/



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