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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Role of the substituent effect over the squarate oxocarbonic ring: Spectroscopy, crystal structure, and density functional theory calculations of 1,2-dianilinosquairane
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Role of the substituent effect over the squarate oxocarbonic ring: Spectroscopy, crystal structure, and density functional theory calculations of 1,2-dianilinosquairane

机译：取代基作用对方酸碳环的作用：1，2-二苯胺基四氢化萘的光谱学，晶体结构和密度泛函理论计算

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This work presents the crystal structure and the investigation under a supramolecular perspective of a squaric acid derivative obtained from the replacement of the hydroxyl groups by anilines. The squaraine obtained (1,2-dianilinesquaraine) crystallizes in the Pbcn space group, in a unit cell with a = 26.5911(8) ?, b = 6.1445(10) ?, and c = 7.5515(5) ?. The bond lengths in the oxocarbon ring, squarate-N and C-O bonds present the character of double bonds. Also the difference between the longer and shorter C-C bond in the four-membered ring (ΔCC) is 0.0667 ?, showing a good degree of equalization of these bond lengths. The phenyl rings are slightly distorted in relation to the squarate ring, and the angle measured between the best plane fitted in each ring is 37.2(9)°. Each molecule is connected to the other through a hydrogen bond involving the N-H?O moieties, where the donor?acceptor distance is 2.826(1) ?, forming ribbons in a unidimensional arrangement C(5)R2~2(10) along the b axis. These structures are mutually connected by π-stacking interactions extending the supramolecular structure in a two-dimensional fashion. Besides, an interesting crossed structure can be easily identified in the formed sheets that are built through the C-H/π interactions. DFT calculations at the B3LYP/6-311++G(d,p) level of theory show an approximately planar molecular structure for the isolated molecule. However, when a dimer model built from hydrogen bonds is considered, the optimized structure presents considerable torsion between the phenyl and squarate rings, as observed in the experimental data. The electronic spectrum shows a strong absorption band at 341 nm that is red-shifted compared to the squarate maximum absorption (290 nm), indicating a more effective electronic delocalization. The most characteristic vibrational modes of the oxocarbon species were used as spectroscopic probe to understand how the substituent groups affect the oxocarbon moiety and, consequently, the vibrational spectra. The analysis shows that the modes associated with the C-C_(ox) bonds are the most affected. Also the character of the double bond of squarate-N and the single bond for the phenyl-N are easily identified. In a general form, the calculated vibrational modes of the dimer model were in better accordance with the experimental data, mainly when the mode has a contribution from the acceptor molecule in the intermolecular interaction.
机译：这项工作介绍了从苯胺取代羟基获得的方酸衍生物的晶体结构和超分子视角的研究。所获得的方酸（1,2-二苯胺基方酸）在Pbcn空间群中以a = 26.5911（8）β，b = 6.1445（10）β和c = 7.5515（5）α的晶胞结晶。碳氧化合物环中的键长，方型N和C-O键具有双键的特征。另外，四元环中较长的和较短的C-C键之间的差（ΔCC）为0.0667Ω，显示出这些键长的良好均等度。苯环相对于方环略微变形，并且每个环中安装的最佳平面之间的夹角为37.2（9）°。每个分子通过一个涉及NH 2 O部分的氢键相互连接，其中供体与受体的距离为2.826（1），沿着b以一维排列C（5）R2〜2（10）形成带状。轴。这些结构通过π-堆叠相互作用相互连接，以二维方式延伸超分子结构。此外，在通过C-H /π相互作用构建的成型板材中，可以轻松地识别出有趣的交叉结构。在理论上B3LYP / 6-311 ++ G（d，p）的DFT计算表明，分离出的分子具有近似平面的分子结构。然而，当考虑到由氢键建立的二聚体模型时，如实验数据中所观察到的，优化的结构在苯环和方环之间表现出相当大的扭转。电子光谱显示在341 nm处有很强的吸收带，与方最大吸收峰（290 nm）相比，该吸收带发生了红移，表明电子离域更有效。含碳化合物种类最典型的振动模式用作光谱探针，以了解取代基如何影响含氧化合物部分，进而影响振动光谱。分析表明，与C-C_（ox）键关联的模式受影响最大。同样容易识别出方-N的双键和苯基-N的单键的特征。在一般形式下，二聚体模型的计算振动模式与实验数据更好地吻合，主要是当该模式在分子间相互作用中受主分子的贡献时。

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