J. Phys. Chem. A, Just Accepted Manuscript
DOI: 10.1021/jp506045q
Publication Date (Web): October 28, 2014
Copyright © 2014 American Chemical Society
Using terahertz time-domain spectroscopy characterization, we observe that urea is able to recognize and interact with uracil efficiently even in solid phase without involving water or solvents. A cocrystal configuration linked by a pair of hydrogen bonds between uracil and urea was formed. Terahertz absorption spectrum of the cocrystal shows a distinct new absorption at 0.8 THz (26.7 cm-1) which originates from the intermolecular hydrogen bonding. Both mechanical milling and heating can accelerate the reaction efficiently. Density functional theory was adopted to simulate the vibrational modes of the cocrystal and the results agree well with the experimental observation. Multi-techniques, including powder X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy were performed to investigate the reaction process and presented supportive evidences. This work enables in-depth understanding of recognition and interaction of urea with nucleobases, and comprehending the denaturation related to RNA. We also demonstrate that terahertz spectroscopy is an effective and alternative tool for online measurement and quality control in pharmaceutical and chemical industry.
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