乙二醇水溶液表面的光谱与计算研究。

Spectroscopic and computational studies of aqueous ethylene glycol solution surfaces.

作者信息

Hommel Elizabeth L, Merle John K, Ma Gang, Hadad Christopher M, Allen Heather C

机构信息

Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.

出版信息

J Phys Chem B. 2005 Jan 20;109(2):811-8. doi: 10.1021/jp046715w.

DOI:10.1021/jp046715w

PMID:16866446

Abstract

The combination of Monte Carlo, ab initio, and DFT computational studies of ethylene glycol (EG) and EG-water hydrogen-bonding complexes indicate that experimental vibrational spectra of EG and EG-water solution surfaces have contributions from numerous conformations of both EG and EG-water. The computed spectra, derived from harmonic vibrational frequency calculations and a theoretical Boltzmann distribution, show similarity to the experimental surface vibrational spectra of EG taken by broad-bandwidth sum frequency generation (SFG) spectroscopy. This similarity suggests that, at the EG and aqueous EG surfaces, there are numerous coexisting conformations of stable EG and EG-water complexes. A blue shift of the CH2 symmetric stretch peak in the SFG spectra was observed with an increase in the water concentration. This change indicates that EG behaves as a hydrogen-bond acceptor when solvated by additional water molecules. This also suggests that, in aqueous solutions of EG, EG-EG aggregates are unlikely to exist. The experimental blue shift is consistent with the results from the computational studies.

摘要

对乙二醇（EG）以及EG - 水氢键复合物进行的蒙特卡罗、从头算和密度泛函理论（DFT）计算研究表明，EG和EG - 水溶液表面的实验振动光谱受到EG和EG - 水多种构象的影响。通过谐波振动频率计算和理论玻尔兹曼分布得出的计算光谱，与通过宽带和频产生（SFG）光谱法测得的EG实验表面振动光谱相似。这种相似性表明，在EG和EG水溶液表面，存在许多稳定的EG和EG - 水复合物共存的构象。随着水浓度的增加，在SFG光谱中观察到CH₂对称伸缩峰发生蓝移。这种变化表明，当被额外的水分子溶剂化时，EG充当氢键受体。这也表明，在EG水溶液中，EG - EG聚集体不太可能存在。实验蓝移与计算研究结果一致。