Centre for THz Research, China Jiliang University, Hangzhou 310018, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Jul;111:192-5. doi: 10.1016/j.saa.2013.03.081. Epub 2013 Apr 2.
Far-infrared vibrational absorption of cocrystal formation between 2,5-dihydroxybenzoic acid (2,5-DHBA) and piracetam compounds under solvent evaporation and grinding methods have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of the formed cocrystals and the involved individual parent molecules in 0.20-1.50 THz region, which probably originated from the intra-molecular and inter-molecular hydrogen bonds due to the presence of two hydroxyl groups in 2,5-DHBA and amide moieties in piracetam compound. The THz absorption spectra of two formed cocrystals with different methods are almost identical. With grinding method, the reaction process can be monitored directly from both time-domain and frequency-domain spectra using THz-TDS technique. The results indicate that THz-TDS technology can absolutely offer us a high potential method to identify and characterize the formed cocrystals, and also provide the rich information about their reaction dynamic process involving two or more molecular crystals in situ to better know the corresponding reaction mechanism in pharmaceutical fields.
采用太赫兹时域光谱（THz-TDS）技术，在室温下研究了 2,5-二羟基苯甲酸（2,5-DHBA）和吡拉西坦化合物在溶剂蒸发和研磨方法下形成共晶时的远红外振动吸收。实验结果表明，在 0.20-1.50 THz 区域内，形成的共晶和所涉及的单个母体分子的吸收光谱存在很大差异，这可能源于 2,5-DHBA 中两个羟基和吡拉西坦化合物中酰胺部分的分子内和分子间氢键。两种不同方法形成的共晶的太赫兹吸收光谱几乎相同。采用研磨法，可使用太赫兹时域光谱技术直接从时域和频域谱中监测反应过程。结果表明，THz-TDS 技术绝对可以为我们提供一种高潜力的方法来识别和表征形成的共晶，并提供有关其反应动力学过程的丰富信息，涉及两个或更多分子晶体的原位，以更好地了解药物领域的相应反应机制。
