The Synthesis And Application Of Flavonoids

Flavonoids are the most widely used natural dyes. In this paper, a series of flavonoidswith different substitutions were designed and synthesized to improve their dyeing propertieson polyester fabric.A series of flavonoids substituted by methoxy, amino, nitro, dimethyl amino, or hydroxygroups were synthesized through the chalcone intermediate, 8 of which have not beenreported in the literatures. The chemical structures of the flavonoids were confirmed by IR,MS, ~1H NMR spectrum and elemental analysis.The synthesized flavonoids were used as dyes on polyester. The dyeing proceeded underhigh temperature and high pressure. The dyeing conditions were optimized and the dyeingresults were evaluated. The dyes have high exhaustion on polyester. The high shade depth canbe realized when the dye concentration is 0.25%. The exhaustions of 4-dimethylamino-2'-hydroxy-4'-methoxy-5'-nitrochalcone and 4'-dimethylamino-7-methoxy-6-nitroflavone arehigher than 98%. The dyes had excellent wash fastness, up to 4-5 grade and moderate rub andsublimation fastness. The light fastness is low because the inherent propensity of flavonoidschromophore to photochemical oxidation.The antibacterial activities of the dyes were also evaluated. Some of them possessmoderate to strong antibacterial activities against Gram-positive Staphylococcus aureusbacteria and Gram-negative Escherichia coli bacteria. Among them,6-Amino-4'-dimethylamino-7-methoxyfavone has the strongest antibacterial activity.