NEW VARIETIES OF CRYSTALLINE ARCHITECTURE PRODUCED BY SMALL CHANGES IN MOLECULAR-STRUCTURE IN TAPE-COMPLEXES OF MELAMINES AND BARBITURATES
NEW VARIETIES OF CRYSTALLINE ARCHITECTURE PRODUCED BY SMALL CHANGES IN MOLECULAR-STRUCTURE IN TAPE-COMPLEXES OF MELAMINES AND BARBITURATES
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DOI：
10.1021/ja00089a020
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发表时间：
1994-05-18
影响因子：
15
通讯作者：
WHITESIDES, GM
中科院分区：
文献类型：
--
作者：
ZERKOWSKI, JA;MATHIAS, JP;WHITESIDES, GM
本文报道了N，N‘-二(间-X-苯基)-三聚氰胺与5，5-二乙基巴比妥酸(X=H、F、Cl、Br、I、CH3和CF3)的7个1：1配合物的晶体结构。本系列提供了对先前研究(Zerkowski，J.A.；MacDonald，J.C.；Seto，C.T.；Wierda，D.A.；Whiteside，G.M.J.Am)中使用的分子结构(N，N‘-双(对-X-苯基)三聚氰胺)的小扰动化学。SoC。在新闻发布会上)。间位和对位络合物都以氢键“带”的形式结晶。然而，由于苯基处于间位，三聚氰胺可以采用更多的分子构象；这一特征导致了更多的堆积取向。Meta系列的包装既有线状的，也有褶皱的带状图案，七个络合物中有四个是溶剂型的。相比之下，使用相同苯基取代基的对映体系列，总是在晶格中产生没有溶剂的线性带状和晶体。溶剂的加入使金属系列成员的堆积系数增加到与对位系列的值大致相同的值。间位系列分子构象的多样性可能是溶剂包合的主要原因，除了间碘与乙腈的络合物外，包合不依赖于特定的非共价相互作用。Meta系列中更广泛的晶体结构仅证明了这些填充形式的动力学可及性；可能会出现热力学稳定性更高的多晶相。这一系列间位取代化合物的多态还没有被研究过。
This paper describes the crystal structures of a series of seven 1:1 complexes between N,N'-bis(m-X-phenyl)-melamine and 5,5-diethylbarbituric acid (X = H, F, Cl, Br, I, CH3, and CF3). This series provides small perturbations on the structures of molecules (N,N'-bis(p-X-phenyl)melamines) used ina previous study (Zerkowski, J. A.; MacDonald, J.C.; Seto, C.T.; Wierda, D.A.; Whitesides, G.M. J. Am. Chem. Soc. In press). Both the meta and para complexes crystallize as hydrogen-bonded ''tapes''. With the phenyl substituent in the meta position, however, the melamines can adopt a greater number of molecular conformations; this feature leads to a greater variety of orientations of packing. The meta series packs in both linear and crinkled tape motifs, and four of the seven complexes are solvates. By contrast, the para series, which used the same set of phenyl substituents, always yielded linear tapes and crystals without solvent in the lattice. Inclusion of solvent increases the packing coefficients of members of the meta series to values approximately equal to those of the para series. The multiplicity of molecular conformations available to the meta series is probably largely responsible for the clathration of solvent, which does not rely upon specific non-covalent interactions except in the case of the m-iodo complex with acetonitrile. The wider range of crystalline architecture in the meta series attests only to the kinetic accessibility of these packing formats; polymorphic phases of greater thermodynamic stability may occur. Polymorphism has not been investigated in the series of meta-substituted compounds.