Journal of Chemical Crystallography ( IF 0.4 ) Pub Date : 2021-07-08 , DOI: 10.1007/s10870-021-00894-1 Xiaoxue Liu 1 , Zhenming Yin 1
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Abstract
The reaction of three equivalents of 2-(trifluoroacetyl)pyrrole with triols [RC(CH2OH)3, R=H, CH3, CH2OH] produce triesters of pyrrole-2-carboxylic acid (1–3, respectively) which crystallize in space groups with molecular C3 symmetry coinciding with the crystallographic symmetry (averaged in the case of R=CH2OH). All are unsolvated. Compound 1 crystallizes in space group P-3 and 2 and 3 in space group P-43n. In all three, molecules form three R22(10) Hydrogen-bonded interactions between syn pyrrole N-H and carboxyl C = O on neighboring molecules. In 1, molecules are linked into infinite chains and hexamolecular rings, and the cavity at the center of the rings (site symmetry − 3) is too small to harbor a guest molecule. In 2 and 3, supramolecular assemblies radiate from four molecules with methyl and hydroxymethyl groups at tetrahedral sites in the cubic structures. Computations confirm the importance of Hydrogen-bonding in these assemblies which add to the hundreds of similar pyrrole carboxylates previously described.
Graphic Abstract
Applications of the R22(10) hydrogen bond motif formed between two pyrrole-2-carboxylate moieties in the design of hydrogen bonded framework. Three tripodal pyrrole-2-carboxylate compounds were synthesized, and their structure were characterized by X-ray crystallography. The three compounds self-assembled into hexamer or cubic supramolecular structures. The relibility of the motif was also proved by DFT calculations and search in Cambridge Structural Database (CSD).
中文翻译：
C3对称性三吡咯-2-羧酸酯的合成及晶体结构
摘要
三当量的 2-（三氟乙酰基）吡咯与三醇 [RC(CH 2 OH) 3 , R=H, CH 3 , CH 2 OH] 反应生成吡咯-2-羧酸的三酯（分别为1–3）它在空间群中结晶，分子 C 3对称性与晶体对称性一致（在 R=CH 2 OH的情况下平均）。都是未溶解的。化合物1在空间群 P-3 中结晶，2和3在空间群 P-43 n 中结晶。在所有这三个，分子形成三个R 2 2（10）氢键之间的相互作用顺相邻分子上的吡咯 NH 和羧基 C = O。在1 中，分子连接成无限链和六分子环，环中心的空腔（位点对称性 - 3）太小而无法容纳客体分子。在图2和图3 中，超分子组装体从四个分子在立方结构的四面体位置处辐射出甲基和羟甲基。计算证实了氢键在这些组件中的重要性，这些组件添加到了先前描述的数百种类似的吡咯羧酸盐中。
图形摘要
在两个 pyrrole-2-carboxylate 部分之间形成的 R 2 2 (10) 氢键基序在氢键框架设计中的应用。合成了三种三足吡咯-2-羧酸酯化合物，并通过X射线晶体学表征了它们的结构。这三种化合物自组装成六聚体或立方体超分子结构。通过 DFT 计算和在剑桥结构数据库 (CSD) 中的搜索也证明了该主题的可靠性。
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