Synthesis and halochromism of new quinoxaline fluorescent dyes

New 6,7-bis-(3-methylbutoxyl)quinoxaline fluorescent dyes with groups of different electron-donating ability were synthesized by the condensation of [3-(diethoxyphosphoryl methyl)-6,7-bis-(3-methylbutoxy)-quinoxalin-2-yl methyl]-phosphonic acid diethyl ester 3 with arylaldehydes. The substituent effects of the donor moiety on the absorption and fluorescent properties in solution were correlated with the nature of the chromophoric systems.