Solvatochromic fluorescence of piperazine-modified bipyridazines for an organic solvent-sensitive film.

Bipyridazines were modified with heterocyclic amines such as piperazine to give symmetric quadrupolar (SPBP) and asymmetric dipolar (APBP) bipyridazine. The fluorescence of SPBP and APBP was highly sensitive to solvent polarity, giving a synthetic rainbow of emission in different organic solvents. The solvent-induced changes in the Stokes shift of the bipyridazines resulted in positive solvatochromism. The symmetric bipyridazine showed higher solvatochromic sensitivity than that of the asymmetric bipyridazine and diazines. The positive solvatochromic fluorescence properties were reproduced in a binary system of toluene/dimethyl sulfoxide (DMSO) mixture, which showed a synthetic rainbow of emission by varying the DMSO content in toluene. An organic sensitive poly(methyl methacrylate) film containing SPBP exhibited a visible sensitivity for the detection of solvents by their polarity upon exposure to organic solvent molecules.