Benavides-Maya Laura Sofía, Torres-Perdomo Manuel Felipe, Ocampo-Carmona Luz M, Echeverry-Vargas Luver
Departamento de Materiales y Minerales, Universidad Nacional de Colombia, Medellin 050034, Colombia.
Department of Metallurgical Engineering, University of Concepcion, Concepción 4070371, Chile.
Molecules. 2025 Mar 31;30(7):1557. doi: 10.3390/molecules30071557.
In this study, a deep eutectic solvent (DES) incorporating protonated caffeine (CafCl), ethylene glycol (EG), and zinc chloride (ZnCl2) was synthesized and characterized for the first time. Caffeine was protonated using an optimized procedure in an anhydrous medium to enhance its interaction with the system, and its structure was confirmed by FTIR spectroscopy, NMR, and thermogravimetric analysis (TGA), evidencing the formation of the N-H bond in the imidazole ring. A eutectic mixture with a molar ratio of ETG:ZnCl2:CafCl of 1:2:0.1 was synthesized, and its characterization confirmed the formation of hydrogen bonds and the coordinative interaction between the components. Additionally, computational simulations based on COSMO-RS and ab initio molecular dynamics (AIMD) were conducted to analyze the charge distribution and the stability of the hydrogen bond network in the eutectic mixture. Sigma profiles revealed that protonated caffeine possesses highly polar regions capable of establishing strong interactions with EG and ZnCl2, enhancing the system's stability. Furthermore, radial distribution functions (RDFs) showed a decrease in the interaction distance between key atoms after incorporating protonated caffeine. The results suggest that this novel DES has promising potential for industrial applications, especially in the extraction of sulfur compounds from fossil fuels due to the activation of the imidazole ring of caffeine. However, further studies are needed to optimize its operating conditions and evaluate its performance on an industrial scale.
在本研究中，首次合成并表征了一种包含质子化咖啡因（CafCl）、乙二醇（EG）和氯化锌（ZnCl2）的深共晶溶剂（DES）。在无水介质中采用优化程序使咖啡因质子化，以增强其与体系的相互作用，并用傅里叶变换红外光谱（FTIR）、核磁共振（NMR）和热重分析（TGA）对其结构进行了确认，证明了咪唑环中N-H键的形成。合成了一种摩尔比为ETG:ZnCl2:CafCl为1:2:0.1的共晶混合物，其表征证实了氢键的形成以及各组分之间的配位相互作用。此外，基于COSMO-RS和从头算分子动力学（AIMD）进行了计算模拟，以分析共晶混合物中电荷分布和氢键网络的稳定性。西格玛分布图显示，质子化咖啡因具有能够与EG和ZnCl2建立强相互作用的高极性区域，增强了体系的稳定性。此外，径向分布函数（RDF）表明，加入质子化咖啡因后关键原子之间的相互作用距离减小。结果表明，这种新型DES在工业应用中具有广阔的潜力，特别是由于咖啡因咪唑环的活化，在从化石燃料中提取硫化合物方面。然而，需要进一步研究来优化其操作条件并在工业规模上评估其性能。
