Crystal Structure of Quinine : Unignorable Affects of Vinyl and Methoxy Groups on Molecular Assemblies of Cinchona Alkaloids
Crystal Structure of Quinine : Unignorable Affects of Vinyl and Methoxy Groups on Molecular Assemblies of Cinchona Alkaloids
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奎宁的晶体结构：乙烯基和甲氧基对金鸡纳生物碱分子组装的不可忽视的影响
DOI：
10.1002/asia.201200566
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and Mikiji Miyata
中科院分区：
文献类型：
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作者：
Ichiro Hisaki;Eri Hiraishi;Toshiyuki Sasaki;Hideo Orita;Seiji Tsuzuki;Norimitsu Tohnai;and Mikiji Miyata
奎宁是金鸡纳生物碱之一，从医学、合成和超分子的角度来看，它引起了极大的兴趣。然而，令人费解的是，尽管奎尼丁、辛可尼丁和辛可宁等其他金鸡纳生物碱的 GF 晶体是已知的，但不含溶剂或其他分子的奎宁的无客体 (GF) 晶体近三十年来一直没有报道。本研究成功揭示了奎宁的晶体结构，其属于P21空间群，晶胞参数为a=6.0587(1)、b=19.2492(5)、c=22.2824(7) Å、β=92.1646(11)°、V=2596.83(12) Å3。有趣的是，该晶体的晶胞中有三个晶体学上独立的分子（Z′=3），它们通过 N（喹啉）·····HO 氢键连接，形成伪三重（32）双螺旋图案。该螺旋图案与其他金鸡纳生物碱的 GF 晶体中观察到的螺旋图案完全不同。对包括奎宁在内的一系列金鸡纳生物碱晶体结构的层次比较清楚地表明，分子的微小结构差异，特别是乙烯基的位置，会导致结晶状态下组装方式的显着变化。目前还没有系统地证明金鸡纳生物碱晶体中这种空间效应的报道，因此，本系统有助于设计所需的功能晶体结构。
Quinine, one of Cinchona alkaloids, has been of great interest from medical, synthetic, and supramolecular viewpoints. However, unaccountably, the guest‐free (GF) crystal of quinine containing no solvent or other molecules has not been reported for nearly three decades, although GF crystals of other Cinchona alkaloids, such as quinidine, cinchonidine, and cinchonine, are already known. In this study, we successfully revealed the crystal structure of quinine, which belongs to theP21space group with the cell parameters ofa=6.0587(1),b=19.2492(5),c=22.2824(7) Å,β=92.1646(11)°, andV=2596.83(12) Å3. Interestingly, the crystal has three crystallographically independent molecules in the cell (Z′=3) that are connected through a N(quinoline)⋅⋅⋅HO hydrogen bond to form a pseudo three‐two‐fold (32) double‐helical motif. The helical motif is completely different from those observed in GF crystals of other Cinchona alkaloids. Hierarchical comparison on the crystal structures of a series of Cinchona alkaloids including quinine clearly demonstrated that only small structural differences of a molecule, particularly the position of the vinyl group, cause a significant variety of assembly manner in the crystalline state. There have been no reports systematically demonstrating such steric effect in crystals of Cinchona alkaloids, and, therefore, the present system contributes to the design of desired functional crystal structures.