Centre for THz Research, China Jiliang University, Hangzhou 310018, China.
Department of Chemisty, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 Nov 5;186:29-36. doi: 10.1016/j.saa.2017.06.011. Epub 2017 Jun 9.
The vibrational spectra of solid-state acyclovir, fumaric acid and their cocrystal have been investigated by using terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy at room temperature. In experimental THz spectra, the cocrystal has absorption peaks in 0.65, 0.94 and 1.10THz respectively, while the raw materials are absolutely different in this region. Raman spectra also show similar results about differences between the cocrystal and raw materials. Density functional theory (DFT) was performed to simulate vibrational modes of different theoretical forms between acyclovir and fumaric acid. The calculation of theoretical THz spectra shows that O8C7N1H27 and the carboxyl group COOH establish a dimer theoretical cocrystal form by the hydrogen bonding effect, which makes contributions to the formation of absorption peaks in 0.70, 1.01 and 1.34THz, and agrees well with experimental observations. The theoretical Raman result also indicates that this dimer form matches with experimental results. The characteristic bands of the cocrystal between acyclovir and fumaric acid are also assigned based on the simulation results from the DFT calculation.
采用太赫兹时域光谱（THz-TDS）和拉曼光谱技术，在室温下对固态阿昔洛韦、富马酸及其共晶的振动光谱进行了研究。在实验 THz 光谱中，共晶在 0.65、0.94 和 1.10THz 处分别有吸收峰，而原料在该区域则完全不同。拉曼光谱也显示了共晶与原料之间差异的类似结果。采用密度泛函理论（DFT）模拟了阿昔洛韦和富马酸不同理论形式之间的振动模式。理论 THz 光谱的计算表明，O8C7N1H27 和羧酸基团 COOH 通过氢键作用形成二聚体理论共晶形式，这有助于在 0.70、1.01 和 1.34THz 处形成吸收峰，与实验观察结果吻合较好。理论拉曼结果也表明，这种二聚体形式与实验结果相符。还根据 DFT 计算的模拟结果，对阿昔洛韦和富马酸共晶的特征谱带进行了归属。
