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Berberine, a natural cationic colorant was successfully employed onto nylon 66 fiber in this research. The effects of three important variables, namely pH, temperature, and liquor ratio were examined on the % exhaustion, color strengths, and color yields of the sample. It has been employed in antimicrobial finishing as a natural agent on nylon 66 due to its characteristics of cationic quaternary ammonium salt. Antimicrobial activity of the sample was studied against Staphylococcus aureus (ATCC 6538) and Klebsiella pneumoniae (ATCC 4352) according to test method KS K 0693-2001 and the corresponding berberine finished sample showed very effective antimicrobial functions showing about 99.9% of bacterial reduction against above-mentioned two bacteria. The maximum % exhaustion, color strengths, and color yields were obtained at 98 8C, alkaline condition (pH 11) and lower liquor ratio (20 : 1). An appropriate predictable empirical models were also developed using Excel solver function incorporating interaction effects of all variables to predict the % exhaustion, color strength(K/S), and the satisfactory results (R 2 > 0.99) were obtained.

The bisazomethine dyes derived from diaminomaleonitrile and aminobenzaldehydes, 2,3-bis[(E)-4-(dialkylamino)benzylideneamino]fumaronitrile derivatives, are known to have potential as dyes for forming J-aggregate vapour-deposited films, even though appropriate conditions for preparation of their pure J-aggregate films are unknown. In this study, an attempt was made to investigate the effects of alkoxy substitution on the crystal structures of eight bisazomethine dyes; our final goal was to obtain pure J-aggregates of bisazomethine dyes in a crystalline state. The focus of this study is on the relationship between changes in the molecular structure and the crystal structure, characterized by a two-dimensional molecular stacking layer and its alignment. We found that the interlayer distance between adjacent two-dimensional stacking layers can be controlled by alkoxy substitution, when the substituent chain length is less than C10, without any significant structural changes in the stacking layer. Our observation was confirmed by lattice energy calculations from an energetic perspective. Scheme 1 Chemical structures of dyes 1-8.

Bisazomethine dyes, which are synthesized using diaminomaleonitrile and aminobenzaldehydes, exhibit red fluorescence in solution and in the solid state. Several bisazomethine dyes are known to form Jaggregates in vapour-deposited films. In this work, novel bisazomethine dyes were synthesized and the effect of phenyl ring substitution on the J-aggregate formation in vapour-deposited films was examined. The optical properties of the dyes were examined in solution and in the solid state through molecular orbital calculations. Four derivatives were found to form J-aggregates in vapour-deposited films as determined from the shape of the spectrum and the absorption edge.

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