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Constraining Carbon Nanothread Structures by Experimental and Calculated Nuclear Magnetic Resonance Spectra
Nano Letters ( IF 9.6 ) Pub Date : 2018-06-28 00:00:00 , DOI: 10.1021/acs.nanolett.8b01736 Tao Wang , Pu Duan 1 , En-Shi Xu , Brian Vermilyea , Bo Chen 2 , Xiang Li , John V. Badding , Klaus Schmidt-Rohr 1 , Vincent H. Crespi
Nano Letters ( IF 9.6 ) Pub Date : 2018-06-28 00:00:00 , DOI: 10.1021/acs.nanolett.8b01736 Tao Wang , Pu Duan 1 , En-Shi Xu , Brian Vermilyea , Bo Chen 2 , Xiang Li , John V. Badding , Klaus Schmidt-Rohr 1 , Vincent H. Crespi
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A one-dimensional (1D) sp3 carbon nanomaterial with high lateral packing order, known as carbon nanothreads, has recently been synthesized by slowly compressing and decompressing crystalline solid benzene at high pressure. The atomic structure of an individual nanothread has not yet been determined experimentally. We have calculated the 13C nuclear magnetic resonance (NMR) chemical shifts, chemical shielding tensors, and anisotropies of several axially ordered and disordered partially saturated and fully saturated nanothreads within density functional theory and systematically compared the results with experimental solid-state NMR data to assist in identifying the structures of the synthesized nanothreads. In the fully saturated threads, every carbon atom in each progenitor benzene molecule has bonded to a neighboring molecule (i.e., 6 bonds per molecule, a so-called “degree-6” nanothread), while the partially saturated threads examined retain a single double bond per benzene ring (“degree-4”). The most-parsimonious theoretical fit to the experimental 1D solid-state NMR spectrum, constrained by the measured chemical shift anisotropies and key features of two-dimensional NMR spectra, suggests a certain combination of degree-4 and degree-6 nanothreads as plausible components of this 1D sp3 carbon nanomaterial, with intriguing hints of a [4 + 2] cycloaddition pathway toward nanothread formation from benzene columns in the progenitor molecular crystal, based on the presence of nanothreads IV-7, IV-8, and square polymer in the minimal fit.
中文翻译：
通过实验和计算的核磁共振谱约束碳纳米线结构。
最近，通过在高压下缓慢压缩和减压结晶固体苯，合成了一种具有高横向堆积顺序的一维（1D）sp 3碳纳米材料，即碳纳米线。单个纳米线的原子结构尚未通过实验确定。我们已经计算了13密度泛函理论中的几个轴向有序和无序的部分饱和和完全饱和的纳米线的C核磁共振（NMR）化学位移，化学屏蔽张量和各向异性，并将结果与实验性固态NMR数据进行系统比较，以帮助识别结构合成的纳米线。在完全饱和的线程中，每个祖先苯分子中的每个碳原子都已与相邻的分子键合（即每个分子6个键，即所谓的“ 6级”纳米线程），而部分饱和的线程保留了一个单倍每个苯环的键数（“ 4级”）。最简化的理论与实验1D固态NMR光谱相符，但受测得的化学位移各向异性和二维NMR光谱的关键特征所限制，3碳纳米材料，基于纳米线IV-7，IV-8和方形聚合物的最小配合，具有从祖先分子晶体中苯柱向纳米线形成[4 + 2]环加成途径的迷人提示。
更新日期：2018-06-28
中文翻译：
通过实验和计算的核磁共振谱约束碳纳米线结构。
最近，通过在高压下缓慢压缩和减压结晶固体苯，合成了一种具有高横向堆积顺序的一维（1D）sp 3碳纳米材料，即碳纳米线。单个纳米线的原子结构尚未通过实验确定。我们已经计算了13密度泛函理论中的几个轴向有序和无序的部分饱和和完全饱和的纳米线的C核磁共振（NMR）化学位移，化学屏蔽张量和各向异性，并将结果与实验性固态NMR数据进行系统比较，以帮助识别结构合成的纳米线。在完全饱和的线程中，每个祖先苯分子中的每个碳原子都已与相邻的分子键合（即每个分子6个键，即所谓的“ 6级”纳米线程），而部分饱和的线程保留了一个单倍每个苯环的键数（“ 4级”）。最简化的理论与实验1D固态NMR光谱相符，但受测得的化学位移各向异性和二维NMR光谱的关键特征所限制，3碳纳米材料，基于纳米线IV-7，IV-8和方形聚合物的最小配合，具有从祖先分子晶体中苯柱向纳米线形成[4 + 2]环加成途径的迷人提示。
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