Structure−activity relationships for hydroxychloroquine compound and its derivatives resulted in a potent antiviral activity. Where hydroxychloroquine derivatives showed an apparent efficacy against coronavirus related pneumonia. For this reason, the current study is focused on the structural properties of hydroxychloroquine and hydroxychloroquine sulfate. Optimized structures of these molecules have been reported by using DFT method at B3LYP/6-31G* level of theory. The geometric were determined and compared with the experimental crystal structure. The intra and intermolecular interactions which exist within these compounds are analyzed by different methods namely the topological analysis AIM, ELF and the reduced gradient of the density. These approaches make it possible in particular to study the properties of hydrogen bonds. The highest occupied molecular orbital and the lowest unoccupied molecular orbital energy levels are constructed and the corresponding frontier energy gaps are determined to realize the charge transfer within the molecule. The densities of state diagrams were determined to calculate contributions to the molecular orbitals. The molecular electrostatic potential surfaces are determined to give a visual representation of charge distribution of these ligands and to provide information linked to electrophilic and nucleophilic sites localization. Finally, these derivatives were evaluated for the inhibition of COVID-19 activity by using the molecular docking method.

羟氯喹化合物及其衍生物的构效关系产生了强大的抗病毒活性。其中羟氯喹衍生物显示出对冠状病毒相关肺炎的明显疗效。因此，目前的研究主要集中在羟氯喹和硫酸羟氯喹的结构特性上。这些分子的优化结构已通过在 B3LYP/6-31G* 理论水平上使用 DFT 方法进行了报道。确定几何结构并与实验晶体结构进行比较。这些化合物中存在的分子内和分子间相互作用通过不同的方法进行分析，即拓扑分析 AIM、ELF 和密度梯度降低。这些方法使得研究氢键的特性成为可能。构建最高占据分子轨道和最低未占据分子轨道能级并确定相应的前沿能隙以实现分子内的电荷转移。确定状态图的密度以计算对分子轨道的贡献。确定分子静电势表面以直观表示这些配体的电荷分布，并提供与亲电和亲核位点定位相关的信息。最后，使用分子对接方法评估了这些衍生物对 COVID-19 活性的抑制作用。