Inter-molecular π–π stacking interactions of aromatic systems play crucial roles in functional nanomaterials and therapeutics. Herein, we developed a series of novel 8-hydroxyquinoline-polycyclic aromatic hydrocarbon (PAH) conjugates (PH1–PH3) by coupling 8-hydroxyquinoline with a series of PAHs such as naphthalene, anthracene, and pyrene. A second series of quinoline-PAH derivatives (PD1–PD3) has also been developed by sulfonating the quinoline –OH of the first series. Crystallographic analyses of these compounds revealed exciting structural and supramolecular features. Supramolecular analyses of PH series compounds revealed that the crystal packing interactions in these compounds are dominated by intermolecular C–H⋯O and C–H⋯π interactions, in which the C–H⋯O interactions lead to the formation of zig-zag 1D chains in the crystal lattice, which are interconnected to a 3D network by various intermolecular C–H⋯π interactions. Compared to the PH series, the supramolecular interactions in the PD series are dominated by π–π and C–H⋯π interactions. In these compounds, two adjacent V-shaped molecules are arranged in a dimeric fashion such that one arm of the V-shaped molecule is packed within the cleft formed by the arms of the other. In the crystal lattice of PD series compounds, such dimers are interconnected through π–π interactions into 1D chains/2D sheets, which are further interconnected into 2D/3D networks through additional C–H⋯π/π–π stacking interactions. The preliminary cytotoxicity properties of PH and PD series compounds were evaluated using human hepatocellular carcinoma cells (HepG2 cells). It was observed that the presence/absence of –OH group on the quinoline ring and the size of the PAH ring play significant roles in determining the cytotoxicity of these compounds. The PH series compounds with an –OH substituent on the quinoline ring exhibited comparatively better cytotoxicity (IC₅₀ values in the range 8.03–11.72 μM) than the PD series compounds (IC₅₀ values in the range 9.48–38.16 μM) with sulfonated quinoline moiety. The compound bearing pyrene PAH and –OH substituent on the quinoline ring exhibited the best cytotoxicity (IC₅₀ = 8.03 μM) among all the compounds tested. The present study, therefore, shows that the quinoline-PAH conjugates can exhibit interesting structural and supramolecular properties along with appreciable cytotoxic effects. Further, these properties could be fine-tuned by changing the size of the PAH ring and the substituent on the quinoline ring.

中文翻译：

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新型8-羟基喹啉-多环芳烃（PAH）缀合物及其磺化衍生物：磺化和PAH尺寸对其结构、超分子和细胞毒性特性的影响

芳香族系统的分子间π-π堆积相互作用在功能纳米材料和治疗学中发挥着至关重要的作用。在此，我们通过将8-羟基喹啉与一系列PAH（例如萘、蒽和芘）偶联，开发了一系列新型8-羟基喹啉-多环芳烃（PAH）缀合物（PH1-PH3）。通过磺化第一个系列的喹啉-OH，还开发了第二个系列的喹啉-PAH衍生物（PD1-PD3）。这些化合物的晶体学分析揭示了令人兴奋的结构和超分子特征。 PH系列化合物的超分子分析表明，这些化合物中的晶体堆积相互作用以分子间C-H⋯O和C-H⋯π相互作用为主，其中C-H⋯O相互作用导致形成锯齿状一维结构。晶格中的链，通过各种分子间 C–H⋯π 相互作用互连成 3D 网络。与PH系列相比，PD系列中的超分子相互作用以π-π和C-H⋯π相互作用为主。在这些化合物中，两个相邻的 V 形分子以二聚体方式排列，使得 V 形分子的一个臂填充在另一个臂形成的裂缝内。在PD系列化合物的晶格中，此类二聚体通过π-π相互作用互连成1D链/2D片，并通过额外的C-H⋯π/π-π堆积相互作用进一步互连成2D/3D网络。使用人肝细胞癌细胞（HepG2 细胞）评估了 PH 和 PD 系列化合物的初步细胞毒性特性。据观察，喹啉环上是否存在 –OH 基团以及 PAH 环的大小在决定这些化合物的细胞毒性方面起着重要作用。喹啉环上带有-OH取代基的PH系列化合物比带有磺化喹啉部分的PD系列化合物（IC _{50值在9.48-38.16 μM范围内）表现出更好的细胞毒性（IC 50}值在8.03-11.72 μM范围内） 。在所有测试的化合物中，喹啉环上带有芘 PAH 和 –OH 取代基的化合物表现出最佳的细胞毒性 (IC ₅₀ = 8.03 μM)。因此，本研究表明喹啉-PAH 缀合物可以表现出有趣的结构和超分子特性以及明显的细胞毒性作用。此外，这些特性可以通过改变 PAH 环的大小和喹啉环上的取代基来微调。