苏丹红系列染料在有机溶液中的紫外-可见光谱研究

研究了苏丹红Ⅰ、苏丹红Ⅲ和苏丹红Ⅳ在非极性溶剂石油醚和极性溶剂乙腈及乙腈-水混合溶液中的紫外-可见光谱特征。在极性溶剂中苏丹红系列的可见区特征吸收峰比在非极性溶液中略有红移;在乙腈-水混合溶液中，苏丹红Ⅰ的特征吸收峰比在乙腈溶剂中红移，最大红移达13 nm，吸收强度最大增幅为34.5%;苏丹红Ⅲ的特征吸收峰红移8 nm，吸收强度增幅为11%;苏丹红Ⅳ的特征吸收峰先红移后蓝移，吸收强度增幅数仅为2.5%。造成这一变化的原因是在乙腈-水混合溶液中，苏丹红Ⅰ, Ⅲ, Ⅳ分子内氢键被破坏，扩大了π键离域范围所致。

UV-Vis Spectroscopic Characterization of Sudan Series in Organic Solution

The UV-Vis spectroscopic characterization of Sudan I, Sudan III and Sudan IV in nonpolar solvent ligarine, polar solvent acetonitrile, and acetonitrile-water mixture was studied. The characteristic absorption peaks of sudan series were a little red shifted in polar solvent compared to that in nonpolar solvent. In acetonitrile-water mixture the red shift of characteristic absorption peaks of sudan I and sudan III is respectively 13 and 8 nm, but the characteristic absorption peaks of sudan IV are red shifted before blue shifted. The increased adsorption strength of Sudan I, Sudan III and Sudan IV is 34.5%, 11% and 2.5% respectively. For these, the important reason is that the destroyed intramolecular hydrogen bond in Sudan series enlarges the scope of the pi delocalized bond in polar solvent.