Rma. Elhamd, ELECTRONIC-SPECTRA OF SOME NEW SYNTHESIZED METHINE CYANINE DYES, Proceedings of the Indian Academy of Sciences. Chemical sciences, 107(2), 1995, pp. 157-170
New methine cyanine dyes such as monomethine (3a-e), azamethine (4a-c)
and trimethine (6a-i) and (8a-c) incorporating a fused pyrazolo [3,4-
d] oxazole nucleus were prepared. The new synthesised cyanines were id
entified by elemental and spectral analyses. The visible absorption sp
ectra of some selected dyes were investigated in pure and mixed solven
ts as well as in aqueous buffer solutions. Molecular complex formation
with ethanol was verified by mixed solvent studies. The variation of
absorbance with pH was utilized for the determination of the pKa value
s for selected compounds.