Chemiluminescence properties of luminol related quinoxaline analogs: Experimental and DFT based approach to photophysical properties

• Spectroscopic investigations of a new series of quinoxaline.
• Photophysical properties were evaluated and correlated with the TD-DFT data.
• Chemiluminescence intensities are superior to the known luminol-isoluminol systems.
• Compounds are thermally stable.

Novel luminol and isoluminol related compounds containing a quinoxaline moiety were synthesized by the reaction of various 1,2-diketones with dimethyl-4,5-diaminophthalate (5) and dimethyl-3,4-diaminophthalate (5′). The UV–Vis absorption and emission spectra of the dyes were studied in solvents of differing polarity and the compounds show solvatofluorism properties. The chemiluminescent properties of the isoluminol and luminol based quinoxaline derivatives were examined and compared with isoluminol and luminol. These compounds produced chemiluminescence by reaction with hydrogen peroxide in the presence of potassium hexacyanoferrate(III) in sodium hydroxide solution. The chemiluminescence intensities of these chemiluminophores were affected by the concentrations of hydrogen peroxide, potassium hexacyanoferrate(III) and sodium hydroxide. These quinoxaline derivatives were found to produce chemiluminescence in the range of 3.2–7.3 and it is 0.57–1.7 times more intensely than isoluminol and luminol, respectively. Density Functional Theory computations have been used for in-depth understanding of structural, molecular, electronic and photophysical parameters of the compounds.

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