Understanding the Molecular Interaction in Solutions by Chemometric Resolution of Near−Infrared Spectra

• Published in: ChemistrySelect (Weinheim) 2017-10, Vol.2 (31), p.10027-10032
• Main Authors: Shao, Xueguang, Cui, Xiaoyu, Liu, Yan, Xia, Zhenzhen, Cai, Wensheng
• Format: Article
• Language: English
• Subjects: Chemometrics; Ethanol-water mixture; Noncovalent interactions; resolution; Vibrational spectroscopy
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201700939

Interactions in aqueous solutions have been extensively studied using spectroscopic techniques. Due to the complexity of the spectra, however, it is difficult to obtain the spectral components showing the interactions in the system. In this study, a chemometric method for resolution of overlapping analytical signals was proposed based on the rotation of the loadings in principal component analysis (PCA). The method was applied to calculating the spectra of ethanol and water from the near infrared (NIR) spectra of ethanol−water mixtures. The calculated spectra were found to be more reliable to reflect the structures in the mixture, from which the interactions between water and C−H groups were observed, the change of the ordered water clusters were revealed, and water was proved to be a sensitive probe for analyzing the structural changes and the interactions in solutions. Furthermore, the difference between the calculated and the measured spectra of the solutions with different concentration was analyzed. It was shown that the interaction of water and ethanol varies non‐linearly with the concentration. Chemometric resolution was applied to the near infrared (NIR) spectra of ethanol−water mixtures. Hydrogen bonding, water structures and the interactions in the solutions with different concentration were discussed.