School of Chemical Engineering and Analytical Science, The University of Manchester, Sackville Street, Manchester M60 1QD, UK.
J Pharm Sci. 2010 Nov;99(11):4453-7. doi: 10.1002/jps.22164.
Combined (15)N ssNMR and X-ray photoelectron spectroscopy (XPS) investigations for theophylline, a theophylline co-crystal, and a theophyllinium salt demonstrate that XPS allows direct observation of the degree of proton transfer, and thus identification of whether a salt or a co-crystal has been formed. The presence of a strongly binding-energy-shifted N 1s XPS peak with protonation indicates a salt (C==NH(+)), while this peak is unmistakably absent in the co-crystal. XPS should be considered as an alternative and complementary technique to single crystal X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy (ssNMR).
联合（15）N ssNMR 和 X 射线光电子能谱（XPS）研究茶碱、茶碱共晶和茶碱𬭩盐表明，XPS 允许直接观察质子转移的程度，从而确定是否形成了盐或共晶。具有强结合能位移的 N 1s XPS 峰的存在表明形成了盐（C==NH(+))，而在共晶中则明显不存在该峰。XPS 应被视为单晶 X 射线衍射和固态核磁共振波谱学（ssNMR）的替代和补充技术。
