Pressure induced polymerization (PIP) of unsaturated molecules like aromatics is highly focused on its production of novel carbon materials like diamond nanothread and graphane. However, the high stability of the aromatic molecules results in a high polymerization pressure at room temperature. To reduce the reaction pressure of the aromatic ring, here we introduced conjugated alkynyl, investigated the PIP of 2,6-diethynylpyridine (2,6-DEP) up to 30.7 GPa, and successfully obtained one-dimensional (1-D) ordered polymers below 10 GPa. In situ Raman and IR spectra show that the alkynyl starts to react at 4–5 GPa. At 5.4 GPa, the critical crystal structure of 2,6-DEP was investigated by in situ X-ray diffraction, and the shortest intermolecular distance was determined as 2.90 Å, between the pyridine ring. The product recovered from 10 GPa shows clearly a 1-D structure via transmission electron microscopy (TEM), and strong diffractions at d = 7.5 and 5.2 Å, corresponding to the interplane distance of the stacked 1-D polymer. Theoretical simulations show that the reaction starts between the alkynyl groups, after which the aromatic rings are drawn close to each other and react. Combining the predicted reaction and the experimental result, we concluded possible models of the product. Our study shows that alkynyl is a good initiator for reducing the polymerization pressure of the aromatics and therefore allows the synthesis of ordered 1-D carbon materials in large scale.

中文翻译：

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2,6-二乙炔基吡啶的高压聚合

芳香族化合物等不饱和分子的压力诱导聚合 (PIP) 高度关注金刚石纳米线和石墨烷等新型碳材料的生产。然而，芳香族分子的高稳定性导致室温下的聚合压力较高。为了降低芳环的反应压力，我们引入了共轭炔基，研究了2,6-二乙炔基吡啶（2,6-DEP）高达30.7 GPa的PIP，成功获得了一维（1-D）有序聚合物低于 10 GPa。原位拉曼和红外光谱显示炔基在 4-5 GPa 下开始反应。在5.4 GPa下，通过原位X射线衍射研究了2,6-DEP的临界晶体结构，确定吡啶环之间的最短分子间距离为2.90 Å。通过透射电子显微镜 (TEM)，从 10 GPa 回收的产物清晰地显示出一维结构，并且在d = 7.5 和 5.2 Å 处有强衍射，对应于堆叠的一维聚合物的面间距离。理论模拟表明，反应在炔基之间开始，之后芳环彼此靠近并发生反应。结合预测的反应和实验结果，我们得出了产品的可能模型。我们的研究表明，炔基是降低芳烃聚合压力的良好引发剂，因此可以大规模合成有序一维碳材料。