The synthesis, structure and spectroscopic properties of novel oxazolone-, pyrazolone- and pyrazoline-containing heterocycle chromophores

A series of novel heterocycle-based chromophores containing oxazolone, pyrazolone or pyrazoline moieties were synthesized under microwave irradiation and characterized using elemental analysis, IR, 1H NMR spectroscopy and mass spectrometry. The crystal structures of two of the dyes were found, using single crystal X-ray crystallography, to be monoclinic, space group P21/c types; the two molecules adopted a Z configuration about the central olefinic bond. The heterocyclic chromophores were fluorescent, with some examples emitting blue light (410–460 nm) whilst others emitted green light (529 nm). The absorption maxima of the chromophores were found to vary from 349 to 463 nm depending on the extent of conjugation.