The ability of Fe³⁺ to bind to Langmuir monolayers of an N, N, N′, N′-dialkyl-N, N′-diacetate ethylenediamine gemini surfactant has been explored. Fe³⁺ in the subphase resulted in the formation of compacted, liquid-phase monolayers with a mesh-like morphology at the micron length scale in comparison with expanded, unstructured liquid-phase monolayers in the absence of iron. The response of the monolayer to subphase Fe³⁺ was different from that reported for Na⁺ and Ca²⁺ for an affiliated, shorter-tail gemini surfactant. Combined surface potential and X-ray reflectivity measurements indicated that Fe³⁺ induced minor conformational changes in the monolayer, suggesting ionic association with the head group. Direct evidence for the binding of iron was provided by total reflection X-ray fluorescence measurements, which revealed that multiple ions were associated with each head group as opposed to chelating with 1:1 stoichiometry as observed with bulk ethylenediaminetetracetic acid. Cumulative data suggest the adsorption of Fe_x(OH)_y^(3x−y)+ complexes with the monolayer surface as has been reported with other charged and uncharged monolayers.

中文翻译：

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乙二胺四乙酸基双子表面活性剂单层膜中的铁结合

已经探索了 Fe ³⁺与 N, N, N', N'-二烷基-N, N'-二乙酸乙二胺双子表面活性剂的 Langmuir 单层结合的能力。与在没有铁的情况下膨胀的非结构化液相单层相比，亚相中的Fe ³⁺导致在微米长度尺度上形成具有网状形态的压实液相单层。单层对亚相 Fe ³⁺的响应不同于对 Na ⁺和 Ca ^{2+ 所}报告的附属的短尾双子表面活性剂的响应。结合表面电位和 X 射线反射率测量表明 Fe ³⁺诱导单层的微小构象变化，表明与头基团的离子结合。全反射 X 射线荧光测量提供了铁结合的直接证据，这表明多个离子与每个头部基团相关，而不是如用本体乙二胺四乙酸观察到的以 1:1 化学计量螯合。累积数据表明 Fe _x (OH) _y ^(3x-y)+复合物与单层表面的吸附正如其他带电和不带电单层所报道的那样。