Abstract The terahertz (THz) absorption spectra of purine and its derivative, uric acid, have been measured by using terahertz time-domain spectroscopy (THz-TDS) system in the frequency range from 0.3 to 1.6 THz. In parallel with the experimental study, the mechanism of the THz characteristic absorption peaks and the weak interaction type of purine and uric acid were investigated by density functional theory (DFT), potential energy distribution (PED), and energy decomposition analysis based on molecular forcefield (EDA-FF) methods. In particular, the specific vibration information provided by the PED analysis is applied to interpret the absorption peak mechanism of the theoretical spectra predicted by DFT. Moreover, the EDA-FF reveals that the weak interactions both for purine and uric acid are dominated by electrostatic interaction, compared with purine the existence of oxygen atoms in uric acid formed more hydrogen bonds among hydrogen and oxygen atoms. Results demonstrate that THz spectroscopy combined with the above three analysis methods provide a valuable reference for the analysis of molecular non-bonded interaction and biomolecules with similar structures.

中文翻译：

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太赫兹光谱和理论计算研究结晶嘌呤和尿酸的分子间弱相互作用

摘要 使用太赫兹时域光谱 (THz-TDS) 系统在 0.3 至 1.6 THz 的频率范围内测量了嘌呤及其衍生物尿酸的太赫兹 (THz) 吸收光谱。在实验研究的同时，通过密度泛函理论(DFT)、势能分布(PED)和基于分子力场的能量分解分析，研究了太赫兹特征吸收峰的形成机制以及嘌呤和尿酸的弱相互作用类型。 (EDA-FF) 方法。特别是，PED 分析提供的特定振动信息用于解释 DFT 预测的理论光谱的吸收峰机制。此外，EDA-FF 揭示了嘌呤和尿酸的弱相互作用以静电相互作用为主，与嘌呤相比，尿酸中氧原子的存在，在氢氧原子之间形成了更多的氢键。结果表明，太赫兹光谱结合上述三种分析方法为分子非键相互作用和结构相似的生物分子的分析提供了有价值的参考。