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首页> 外文期刊>Chemistry: A European journal >Full characterization of colloidal solutions of long-alkyl-chain-amine- stabilized Zno nanoparticles by NMR spectroscopy: Surface state, equilibria, and affinity
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Full characterization of colloidal solutions of long-alkyl-chain-amine- stabilized Zno nanoparticles by NMR spectroscopy: Surface state, equilibria, and affinity

机译：长烷基链胺稳定的Zno纳米颗粒的胶体溶液的NMR表征：表面状态，平衡和亲和力

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摘要

Full NMR characterization of ZnO nanoparticles (NPs) stabilized by various amines (hexadecylamine, dodecylamine, and octylamine) in C _7D _8 demonstrated that the surface of this apparently simple system was very complex. Using different NMR spectroscopic techniques (~1H, PGSE-NMR, diffusion-filtered ~1H NMR, NOESY, ROESY), we observed at least three different modes of interaction of the amines at the surface of the NPs, in thermodynamic equilibrium with the free amines, the relative populations of which varied with their concentration. The first mode corresponded to a strong interaction between a small amount of amine and the ZnO NPs (k _(desorp)≈13 s ~(-1)). The second mode corresponded to a weak interaction between the amines and the surface of the ZnO NPs (k _(off)(2)≈50-60 s ~(-1)). The third, and weakest, mode of interaction corresponded to the formation of a second ligand shell by the amine around the NPs that was held together through van der Waals interactions (k _(off)(1)≈25×10 ~5 s ~(-1)). The second and third modes were in fast exchange on the NMR timescales with the free amines. The strongly interacting amines at the NPs surface (first mode) were in slow exchange with the other modes. A complex hydrogen-bonding network at the NPs surface was also observed, which did not only involve the coordinated amine but also THF and water molecules that remained from the synthesis.
机译：在C _7D _8中，由各种胺（十六烷基胺，十二烷基胺和辛胺）稳定的ZnO纳米颗粒（NP）的完整NMR表征表明，该表面简单的系统表面非常复杂。使用不同的NMR光谱技术（〜1H，PGSE-NMR，扩散过滤的〜1H NMR，NOESY，ROESY），我们观察到NP表面上胺的至少三种不同相互作用方式，与游离态处于热力学平衡状态。胺，其相对种群随浓度而变化。第一模式对应于少量的胺和ZnO NP之间的强相互作用（k _（desorp）≈13s〜（-1））。第二种模式对应于胺与ZnO NPs表面之间的弱相互作用（k _（off）（2）≈50-60s〜（-1））。第三种也是最弱的相互作用模式对应于通过范德华相互作用（k _（off）（1）≈25×10〜5 s〜 （-1））。第二和第三种模式在NMR时标上与游离胺快速交换。 NPs表面的强相互作用胺（第一模式）与其他模式的交换缓慢。还观察到在NPs表面有一个复杂的氢键网络，该网络不仅涉及配位胺，还包括合成中残留的THF和水分子。

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