Mechanistic insights into the pressure-induced polymerization of aryl/perfluoroaryl co-crystals
Mechanistic insights into the pressure-induced polymerization of aryl/perfluoroaryl co-crystals
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对芳基/全氟芳基共晶压力诱导聚合的机理见解
DOI：
10.1039/d1py01387d
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发表时间：
2022
影响因子：
4.6
通讯作者：
Elacqua, Elizabeth
中科院分区：
文献类型：
--
作者：
Gerthoffer, Margaret C.;Xu, Bohan;Wu, Sikai;Cox, Jordan;Huss, Steven;Oburn, Shalisa M.;Lopez, Steven A.;Crespi, Vincent H.;Badding, John V.;Elacqua, Elizabeth
最近发现的金刚石纳米线提供了一种刚性的sp3杂化骨架，这种骨架在传统的聚合物合成中是无法实现的，它是通过简单芳烃的固态压力诱导聚合形成的。该方法使得单体A-B交替能够以序列限定的方式从共晶设计完全转化为聚合物主链。在这里，我们报告的压缩芳基：全氟芳基（Ar/ArF）共晶体含有-OH和-CHO官能团。我们分析了这些官能团聚合的耐受性，探索酮-烯醇互变异构的可能性，并比较了有针对性的固态Ar/ArF设计对纳米线形成的反应结果。采用缓慢溶剂挥发法合成了苯酚：五氟苯甲醛（ArOH：ArFCHO）和苯甲醛：五氟苯酚（ArCHO：ArFOH）两种新型共晶。单晶结构的分析揭示了不同的氢键模式之间的-OH和-CHO在每种固体（磁带和正交二聚体，分别），除了显着不同的π-π堆积距离内的Ar/ArF电子。原位拉曼光谱用于监测每个共晶压缩到21 GPa，并说明压缩过程中-OH和-CHO拉伸区域的峰位移。对于具有最小π-π堆积距离的共晶，对应于聚合的光致发光出现在较低压力下。然而，具有较大质心：质心和质心：平面π-π堆叠距离的回收固体的特征在于与共晶衍生的纳米线堆积的预期尺寸一致的衍射环，表明官能团相互作用和平行堆叠都影响压力诱导的聚合以形成纳米线。 回收的样品的IR光谱显示-OH和-CHO拉伸区域的大位移，特别是对于ArCHO：ArFOH是可伸缩的，这可以反映与在压力下形成刚性线骨架相关的几何约束。模拟表明，氢键网络可以影响共晶沿着线形成轴的相对可压缩性，以调节纳米线形成的倾向。
Recently discovered diamond nanothreads offer a stiff, sp3-hybridized backbone unachievable in conventional polymer synthesis that is formed through the solid-state pressure-induced polymerization of simple aromatics. This method enables monomeric A-B alternation to fully translate from co-crystal design to polymer backbone in a sequence-defined manner. Here, we report the compression of aryl:perfluoroaryl (Ar/ArF) co-crystals containing –OH and –CHO functional groups. We analyze the tolerance of these functional groups to polymerization, explore the possibility of keto–enol tautomerization, and compare the reaction outcomes of targeted solid-state Ar/ArF design on nanothread formation. Two new co-crystals comprising phenol:pentafluorobenzaldehyde (ArOH:ArFCHO) and benzaldehdye:pentafluorophenol (ArCHO:ArFOH) were synthesized through slow solvent evaporation. Analysis of the single-crystal structures revealed different hydrogen bonding patterns between the –OH and –CHO in each solid (tape and orthogonal dimers, respectively), in addition to markedly different π–π stacking distances within the Ar/ArF synthons. In situ Raman spectroscopy was used to monitor the compression of each co-crystal to 21 GPa and illustrated peak shifts for the –OH and –CHO stretching regions during compression. Photoluminescence corresponding to polymerization appeared at a lower pressure for the co-crystal with the smallest π–π stacking distance. Nevertheless, the recovered solid with the larger centroid : centroid and centroid : plane π–π stacking distances featured a diffraction ring consistent with the anticipated dimensions of a co-crystal-derived nanothread packing, indicating that both functional group interactions and parallel stacking affect the pressure-induced polymerization to form nanothreads. IR spectroscopy of the recovered samples revealed large shifts in the –OH & –CHO stretching regions, particularly noticable for ArCHO:ArFOH, which may reflect geometrical constraints associated with forming a rigid thread backbone under pressure. Simulation suggests that hydrogen bonding networks may affect the relative compressibility of the co-crystal along a thread-forming axis to modulate the propensity for nanothread formation.