Unveiling the Amphiphilic Nature of TMAO by Vibrational Sum Frequency Generation Spectroscopy
Unveiling the Amphiphilic Nature of TMAO by Vibrational Sum Frequency Generation Spectroscopy
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DOI：
10.1021/acs.jpcc.6b04852
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发表时间：
2016-07
影响因子：
3.7
通讯作者：
Tatsuhiko Ohto;E. Backus;W. Mizukami;J. Hunger;M. Bonn;Yuki Nagata
中科院分区：
文献类型：
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作者：
Tatsuhiko Ohto;E. Backus;W. Mizukami;J. Hunger;M. Bonn;Yuki Nagata
通过结合外差探测和频产生（SFG）光谱，从头算分子动力学（AIMD）模拟，和后振动自洽场（VSCF）的方法，我们揭示了两亲性的三甲胺-N-氧化物（TMAO）在水/空气界面的取向和表面活性。测量和模拟的C-H伸缩SFG谱都显示出强负峰和弱正峰。我们将这些峰分别归因于甲基的对称伸缩模/费米共振和反对称面内模。这些积极的和消极的功能证明，甲基TMAO优先向空气相。此外，我们探讨了TMAO对界面水结构的影响。O-H伸缩SFG谱表明TMAO-水溶液/空气界面的氢键网络与胺-N-氧化物（AO）表面活性剂/水界面的氢键网络相似。这表明，无论…
By combining heterodyne-detected sum-frequency generation (SFG) spectroscopy, ab initio molecular dynamics (AIMD) simulation, and a post-vibrational self-consistent field (VSCF) approach, we reveal the orientation and surface activity of the amphiphile trimethylamine-N-oxide (TMAO) at the water/air interface. Both measured and simulated C–H stretch SFG spectra show a strong negative and a weak positive peak. We attribute these peaks to the symmetric stretch mode/Fermi resonance and antisymmetric in-plane mode of the methyl group, respectively, based on the post-VSCF calculation. These positive and negative features evidence that the methyl groups of TMAO are oriented preferentially toward the air phase. Furthermore, we explore the effects of TMAO on the interfacial water structure. The O–H stretch SFG spectra manifest that the hydrogen bond network of the aqueous TMAO-solution/air interface is similar to that of the amine-N-oxide (AO) surfactant/water interface. This demonstrates that, irrespective of the...