Studies on some new bridgehead nitrogen heterocyclic cyanine dyes

New asymmetrical mono-(tri)-mechine and azomethine cyanine dyes of pyrazolo [5,4-b] quinolino [a,b]-1,4-pyra-(oxa)-zinium bromide salts were prepared. The new synthesized cyanines were identified by elemental and spectral anal yses. The visible absorption spectra of some selected dyes were investigate d in single and mixed solvents, and also in aqueous buffer solutions. The s pectral shifts were studied in relation to molecular structure and in terms of medium effects. Molecular complex formation with DMF was verified throu gh mixed-solvent studies.