Fluorine containing colorants - dichroic and NLOphoric dyes

摘要

FLUORINE occurs in colorant molecules as a substituent in aromatic moiety as well as a fluoroalkyl group. Occurence of fluorine in dyestuffs was found to enhance the light fastness properties. It was found that the perfiuoro alkyl substituted coumarins and azopyridones were more photo-stable than the unsubstituted counterparts. Fast bases containing trifluoromethyl groups were known. Animic azo dyes containing fluoro as well as perfiuoro alkyl groups were shown to have different aggregation behaviour. Fluorine-containing pigments are known to have better heat stability. A fluorine atom as a leaving group on pyrimidine and triazine moieties in reactive dyes was imporant particularly for reactive dyes used in printing. Fluorine atom when it occurs in organic molecules introduces some special physical and chemical properties. A fluorine atom shows the largest electronegativity among all elements. Thus, fluorine atom as well as polyfiuoro alkyl and perfluoro alkyl groups show strong electron- with drawing ability.