Polymorphic crystals of ambroxol, forms I and II, and form A ambroxol hydrochloride crystals were characterized with bromine K-edge X-ray absorption near-edge structure (XANES) spectroscopy and single-crystal X-ray structure analysis. The XANES spectra had unique shapes depending on the crystal forms. Refined single-crystal structures revealed different interatomic interactions around bromine atoms, such as C–H…Br and N–H…Br hydrogen bonds, Br…O halogen bonds, and N–H…π interactions. Differences in these weak interactions could affect the electronic states of the bromines, resulting in differences in the XANES spectra. The results demonstrated that weak non-conventional interatomic interactions could alter the shape of XANES spectra. Hence, the spectra could be used for evaluating polymorphs of active pharmaceutical ingredients.

采用溴 K 边 X 射线吸收近边结构 (XANES) 光谱和单晶 X 射线结构分析对氨溴索晶型 I 和 II 以及晶型 A 盐酸氨溴索晶体进行了表征。XANES 光谱具有独特的形状，具体取决于晶体形式。精细的单晶结构揭示了溴原子周围不同的原子间相互作用，例如 C–H…Br 和 N–H…Br 氢键、Br…O 卤素键和 N–H…π 相互作用。这些弱相互作用的差异可能会影响溴的电子态，从而导致 XANES 光谱的差异。结果表明，弱的非常规原子间相互作用可以改变 XANES 光谱的形状。因此，该光谱可用于评估活性药物成分的多晶型物。