Department of Chemistry, CQC, University of Coimbra, P-3004-535 Coimbra, Portugal.
Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", CMIC, Politecnico di Milano, 20133 Milano, Italy.
Molecules. 2020 Jul 6;25(13):3083. doi: 10.3390/molecules25133083.
Thiabendazole (TBZ) is a substance which has been receiving multiple important applications in several domains, from medicine and pharmaceutical sciences, to agriculture and food industry. Here, a comprehensive multi-technique investigation on the molecular and crystal properties of TBZ is reported. In addition, a new solvate of the compound is described and characterized structurally, vibrationally and thermochemically for the first time. Density functional theory (DFT) calculations were used to investigate the conformational space of thiabendazole (TBZ), revealing the existence of two conformers, the most stable planar form and a double-degenerated-by-symmetry form, which is ~30 kJ mol higher in energy than the conformer. The intramolecular interactions playing the major roles in determining the structure of the TBZ molecule and its conformational preferences were characterized. The UV-visible and infrared spectra of the isolated molecule (most stable conformer) were also calculated, and their assignment undertaken. The information obtained for the isolated molecule provided a strong basis for the understanding of the intermolecular interactions and properties of the crystalline compound. In particular, the infrared spectrum for the isolated molecule was compared with that of crystalline TBZ and the differences between the two spectra were interpreted in terms of the major intermolecular interactions existing in the solid state. The analysis of the infrared spectral data was complemented with vibrational results of up-to-date fully-periodic DFT calculations and Raman spectroscopic studies. The thermal behavior of TBZ was also investigated using differential scanning calorimetry (DSC) and thermogravimetry. Furthermore, a new TBZ-formic acid solvate [2-(1,3-thiazol-4-yl)benzimidazolium formate formic acid solvate] was synthesized and its crystal structure determined by X-ray diffraction. The Hirshfeld method was used to explore the intermolecular interactions in the crystal of the new TBZ solvate, comparing them with those present in the neat TBZ crystal. Raman spectroscopy and DSC studies were also carried out on the solvate to further characterize this species and investigate its temperature-induced desolvation.
噻苯达唑（TBZ）是一种在医学、药学、农业和食品工业等多个领域得到广泛应用的物质。本文报道了对 TBZ 的分子和晶体性质进行的综合多技术研究。此外，首次对该化合物的一种新溶剂化物进行了结构、振动和热化学的描述和表征。密度泛函理论（DFT）计算用于研究噻苯达唑（TBZ）的构象空间，揭示了存在两种构象，最稳定的平面构象和由对称双重简并的构象，后者的能量比构象高约 30 kJ/mol。确定 TBZ 分子结构及其构象偏好的主要分子内相互作用进行了表征。还计算了分离分子（最稳定构象）的紫外-可见和红外光谱，并对其进行了归属。获得的孤立分子信息为理解晶体化合物的分子间相互作用和性质提供了坚实的基础。特别是，将孤立分子的红外光谱与 TBZ 的晶体红外光谱进行了比较，并根据存在于固态中的主要分子间相互作用对两个光谱之间的差异进行了解释。对红外光谱数据的分析辅以最新的全周期 DFT 计算和拉曼光谱研究的振动结果。还使用差示扫描量热法（DSC）和热重分析研究了 TBZ 的热行为。此外，合成了一种新的 TBZ-甲酸溶剂化物[2-（1,3-噻唑-4-基）苯并咪唑鎓甲酸盐甲酸溶剂化物]，并通过 X 射线衍射确定了其晶体结构。使用 Hirshfeld 方法研究了新 TBZ 溶剂化物晶体中的分子间相互作用，将其与纯 TBZ 晶体中的相互作用进行了比较。还对溶剂化物进行了拉曼光谱和 DSC 研究，以进一步表征该物质并研究其温度诱导的去溶剂化。
