ABSORPTION AND FLUORESCENCE-SPECTRA OF TH E SOLUTIONS OF POLYMERIC SCHIFF-BASES BASED ON FLUOROPHORIC DIAMINES - INFLUENCE OF THE ACIDITY OF THE MEDIUM

A study was performed to reveal how the nature of fluorophoric diamine s and the acidity of medium affect the absorption and fluorescence spe ctra of the solutions of polymeric Shiff bases containing the fluoresc ent fragments in the main chain. It was shown that the fluorescence of the solutions of polymeric Shiff bases in aprotic or protic solvents is observed at long or short wavelengths, respectively. This is the ca se because, on protonation, the unshared electron pair of the nitrogen atom of azomethine group and the n-electrons of the nitrogen atoms fr om the residues of fluorophoric diamines are excluded from the conjuga tion chain of a fluorophore; hence, the conjugation chain becomes shor ter. The fluorescent properties of polymeric Shiff bases based on ioni c fluorophoric diamines are determined by the form (cationic or anioni c) of diamine residues in the polymer chain.