Until now, the lightfastness of hair dyes had not been investigated using all‐valence molecular orbital methods. The results of calculations are used to obtain the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) frontier electron density, which can reflect the propensity for electrophilic or nucleophilic attack at an atom in a molecule. Using semi‐empirical quantum chemical methods AM1 and PM3, we have calculated the reactivity rates , superdelocalisability and electron density distribution in the tested dyes. We have found that the photooxidation of hair dyes (photochemical decomposition of hair dyes) and derivatives of N‐β‐hydroxyethylamino‐o‐nitrobenzene occurs through the degradation of the N‐β‐hydroxyethylamine substituent and on C₂ or C₄ atom (C₄–NO₂) in the process of electrophilic reaction with singlet oxygen ¹O₂ or nucleophilic reaction on the C₁ carbon atom of the aromatic ring, with the use of superoxide anion radical O₂^●. The structures of the dyes were optimised using MM+, DM and AM1 or PM3 until constant energy value was realised with a 0.01 kcal/mol convergence criterion.

中文翻译：

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N-β-羟乙基氨基-邻硝基苯基衍生物的光褪色预测：一项理论研究

到目前为止，尚未使用全价分子轨道方法研究染发剂的耐光性。计算结果用于获得最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）前沿电子密度，这可以反映出分子中某个原子发生亲电或亲核攻击的倾向。使用半经验量子化学方法AM1和PM3，我们已经计算出了被测染料的反应速度，超离域性和电子密度分布。我们已经发现，染发剂（染发剂的光化学分解）和衍生物的光氧化Ñ -β-hydroxyethylamino- ö硝基苯穿过的降解发生Ñ-β-羟乙胺取代基，并且在与单线态氧¹ O _2进行亲电反应或在芳环的C ₁碳原子上进行亲核反应的过程中，在C ₂或C ₄原子（C ₄ -NO ₂）上使用超氧阴离子自由基O ₂ ^{● }。使用MM +，DM和AM1或PM3优化染料的结构，直到以0.01 kcal / mol的收敛标准实现恒定的能量值。