Structure Analysis and Derivation of Deformed Electron Density Distribution of Polydiacetylene Giant Single Crystal by the Combination of X-ray and Neutron Diffraction Data
Structure Analysis and Derivation of Deformed Electron Density Distribution of Polydiacetylene Giant Single Crystal by the Combination of X-ray and Neutron Diffraction Data
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结合X射线和中子衍射数据的聚二乙炔巨型单晶结构分析及变形电子密度分布推导
DOI：
10.1021/acs.macromol.8b00650
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发表时间：
2018
期刊：
影响因子：
5.5
通讯作者：
Tamada Taro
中科院分区：
文献类型：
--
作者：
Tashiro Kohji;Kusaka Katsuhiro;Hosoya Takaaki;Ohhara Takashi;Hanesaka Makoto;Yoshizawa Yoshinori;Yamamoto Hiroko;Niimura Nobuo;Tanaka Ichiro;Kurihara Kazuo;Kuroki Ryota;Tamada Taro
采用广角中子衍射和x射线衍射两种不同的方法对聚二乙炔巨单晶的晶体结构进行了分析。x射线结果给出了聚合物链的总电子密度分布[ρ(x)]。中子的结果告诉我们原子核的位置，这可以让我们推测非键孤立原子周围的电子密度分布[ρ0(x)]。因此，所谓的成键（或变形）电子密度Δρ(x)[≡ρ(x) - ρ0(x) = ρ x (x) - ρ n (x)]，即共价键成的原子沿聚合物链的共轭电子密度分布，可以利用x射线和中子数据分析获得的两个信息（即所谓的x射线-中子减法（x - n）方法）来估计。本报告是X-N方法应用于合成聚合物的第一个例子。聚二乙炔的推导式Δρ(x)与具有相似电子共轭化学式的低分子量模型化合物相似。利用密度泛函理论计算了Δρ(x)，与实验结果定性吻合较好。
The crystal structure of polydiacetylene giant single crystal has been analyzed on the basis of the two different methods of wide-angle neutron diffraction and X-ray diffraction. The X-ray result gives us the total electron density distribution [ρ(x)] of polymer chain. The neutron result tells the positions of atomic nuclei, which can allow us to speculate the electron density distributions [ρ0(x)] around the nonbonded isolated atoms. As a result, the so-called bonded (or deformed) electron density Δρ(x) [≡ ρ(x) – ρ0(x) = ρX(x) – ρN(x)], i.e., the electron density distribution due to the conjugation among the covalently bonded atoms along the polymer chain, can be estimated using the two information obtained by the X-ray and neutron data analyses (the so-called X-ray–neutron subtraction (X–N) method). The present report is the first example of the application of X–N method to the synthetic polymer species. The Δρ(x) derived for polydiacetylene was found similar to that of the low-molecular-weight model compound having the similar electronically conjugated chemical formula. The Δρ(x) was calculated by the density functional theory, which was in a good agreement with the experimental result qualitatively.