Catalán César A N, Justino Licínia L G, Fausto Rui, Ildiz Gulce O, Brandán Silvia Antonia
Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, San Miguel de Tucumán 4000, Argentina.
CQC-IMS, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
Molecules. 2025 Aug 5;30(15):3286. doi: 10.3390/molecules30153286.
In this work, the structures of the isolated anion and anhydrous and monohydrated sodium salts of alizarin red S (ARS) have been theoretically investigated within the density functional theory framework (B3LYP/6-311++G** calculations). The combination of calculations with the scaled quantum mechanics force field (SQMFF) methodology has allowed the assignment of the experimental infrared spectrum of ARS in the solid phase and the determination of the corresponding force constants. The structural analysis also included the investigation of the NMR and UV-visible spectra of the compound in solution in light of the undertaken quantum chemical calculations, the obtained theoretical data being in good agreement with the corresponding experimental ones. The impact of the presence of the Na counterion and hydration water on the properties of the organic ARS fragment was evaluated. Atoms in molecules theory (AIM) analysis was also undertaken to obtain further details on the electronic structure of the investigated species, and the HOMO-LUMO gap was determined to evaluate their relative reactivity. Globally, the results obtained in this work extend the available information on alizarin red S and may also be used for the fast identification of the three studied species of the compound investigated (anhydrous and monohydrated sodium salts and isolated anion).
在本研究中，在密度泛函理论框架内（B3LYP/6 - 311++G**计算）对茜素红S（ARS）的分离阴离子以及无水和一水合钠盐的结构进行了理论研究。计算与标度量子力学力场（SQMFF）方法的结合使得能够归属ARS在固相中的实验红外光谱并确定相应的力常数。结构分析还包括根据所进行的量子化学计算研究该化合物在溶液中的核磁共振和紫外可见光谱，所获得的理论数据与相应的实验数据吻合良好。评估了Na抗衡离子和水合水的存在对有机ARS片段性质的影响。还进行了分子中的原子理论（AIM）分析以获取有关所研究物种电子结构的更多细节，并确定最高占据分子轨道 - 最低未占据分子轨道（HOMO - LUMO）能隙以评估它们的相对反应活性。总体而言，本研究获得的结果扩展了关于茜素红S的现有信息，也可用于快速鉴定所研究的该化合物的三种物种（无水和一水合钠盐以及分离阴离子）。
