A series of N-pyridyl ureas bearing 1,2,4- (1a, 2a, and 3a) and 1,3,4-oxadiazole moiety (1b, 2b, 3b) was prepared and characterized by HRMS, ¹H and ¹³C NMR spectroscopy, as well as X-ray diffraction. The inspection of the crystal structures of (1–3)a,b and the Hirshfeld surface analysis made possible the recognition of the (oxadiazole)···(pyridine) and (oxadiazole)···(oxadiazole) interactions. The presence of these interactions was confirmed theoretically by DFT calculations, including NCI analysis for experimentally determined crystal structures as well as QTAIM analysis for optimized equilibrium structures. The preformed database survey allowed the verification of additional examples of relevant (oxadiazole)···π interactions both in Cambridge Structural Database and in Protein Data Bank, including the cocrystal of commercial anti-HIV drug Raltegravir.

中文翻译：

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涉及 1,2,4- 和 1,3,4-恶二唑系统的 π-π 非共价相互作用：联合实验、理论和数据库研究

制备了一系列带有 1,2,4- ( 1a , 2a和3a ) 和 1,3,4-恶二唑部分 ( 1b , 2b , 3b )的N-吡啶基脲，并通过 HRMS、¹ H 和¹³ C表征核磁共振光谱，以及 X 射线衍射。( 1 – 3 ) a , b的晶体结构检查和 Hirshfeld 表面分析使识别（恶二唑）……（吡啶）和（恶二唑）……（恶二唑）相互作用成为可能。这些相互作用的存在通过 DFT 计算在理论上得到证实，包括用于实验确定的晶体结构的 NCI 分析以及用于优化平衡结构的 QTAIM 分析。预先形成的数据库调查允许验证剑桥结构数据库和蛋白质数据库中相关（恶二唑）…π相互作用的其他例子，包括商业抗 HIV 药物 Raltegravir 的共晶。