Colour modulation of blue anthocyanin-derivatives. Lignosulfonates as a tool to improve the water solubility of natural blue dyes
Colour modulation of blue anthocyanin-derivatives. Lignosulfonates as a tool to improve the water solubility of natural blue dyes
复制标题
DOI：
10.1016/j.dyepig.2018.02.019
复制
发表时间：
2018-06-01
影响因子：
4.5
通讯作者：
Oliveira, Joana
中科院分区：
文献类型：
--
作者：
Araujo, Paula;Basilio, Nuno;Oliveira, Joana
采用紫外-可见光谱法研究了木质素磺酸盐（钙）（L）对两种花青素衍生的蓝色染料（portisin，P和pyranoanthocyanin dimer，PD）在水溶液中的色度特征的影响。结果表明，在pH 1的每个染料和这种大分子之间的相互作用发生两种机制，协会和copigmentation是依赖于L浓度。例如，在低浓度的L（高达0.27 μ M）下，观察到染料与木质素的络合促进了染料的缔合（不同的染料分子结合到L的相同结合位点）。在较高浓度的L（25 μ M），染料的聚集减少，每个分子被绑定到一个不同的网站L导致形成的电荷转移复合物（共色素）。此外，两种染料的滴定（P和PD）在L（19 μ M）存在下，通过相当高的pK（a1）显示其吡喃鎓阳离子形式的强稳定性（P和PD分别为6.6 +/- 0.1和6.2 +/- 0.1，当与不存在时获得的值（pK（a1）= 4.61 +/- 0.03和4.93 +/- 0.04）相比时，还通过比浊法评价了在L不存在和存在下染料的水溶性，结果表明水溶性木质素磺酸盐随时间的推移改善了染料的溶解度。
The impact of a lignosulfonate (calcium) (L) on the chromatic features of two anthocyanin-derived bluish dyes (portisin, P and pyranoanthocyanin dimer, PD) was evaluated in aqueous solutions using UV-Visible spectroscopy. It was demonstrated that the interaction between each dye and this macromolecule at pH 1 occurs by two mechanisms, association and copigmentation that are dependent on L concentration. For instance, at low concentrations of L (up to 0.27 mu M) it is observed the association of dyes promoted by their complexation with lignin (different molecules of dye are bound to the same binding sites of L). At higher concentrations of L (25 mu M), the aggregation of dyes decreases and each molecule is bound to a different site of L resulting in the formation of a charge-transfer complex (copigmentation). Moreover, the titration of both dyes (P and PD) in the presence of L (19 mu M) showed a strong stabilization of their pyranoflavylium cation forms revealed by the considerably higher pK(a1) (6.6 +/- 0.1 and 6.2 +/- 0.1 for P and PD, respectively) in the presence of this macromolecule when compared to the values obtained in the absence (pK(a1) = 4.61 +/- 0.03 and 4.93 +/- 0.04).In addition, the water solubility of the dyes in the absence and presence of L was also evaluated by turbidimetry and the results showed that the water soluble lignosulfonate improved the solubility of the dyes over time.