Isomeric constellations of encapsulation complexes store information on the nanometer scale.
Isomeric constellations of encapsulation complexes store information on the nanometer scale.
复制标题
封装复合物的同分异构群存储纳米级的信息。
DOI：
10.1002/anie.200390189
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
RebekJr,Julius
中科院分区：
文献类型：
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作者：
Shivanyuk,Alexander;RebekJr,Julius
化学中的异构体是通过结构来定义的。两个分子之间的进一步立体化学关系可以通过构型和构象来分配，但是分子的集合也可以通过它们在空间中的排列来显示异构性。我们在这里报告一种新形式的异构体所造成的封装的三个小分子客人在一个圆柱形的，可逆组装的主机。客体分子在主体中的流动性是有限的：客体分子在有限空间内被保持在不同的星座中。胶囊的各种组合和异构星座是纳米级数据存储设备。包封复合物是可逆形成的组装体，其中小分子客体被多分子主体包围。该系统通过弱分子间力（包括金属±配体相互作用和氢键）保持在一起。这些集合是动态的;它们的形成和消散时间尺度从毫秒到小时不等。将分子限制在分子内的机械屏障为异构提供了新的可能性，首先在共价结合的碳配体中观察到。[1]在可逆结合的包封复合物中，[2]阵列的寿命取决于客体的移动性，无论是在胶囊内还是通过与外部分子的交换，在溶液中。我们在这里报告异构星座-安排几个分子在空间中出现时，两个不同的客人，被封装在一个圆柱形主机。[3]具体而言，包封复合物（图1）中氯仿和异丙基氯的所有组合均可通过NMR方法鉴定。同分异构现象是集合体而不是单个分子的一种突现性质。该现象暗示了通过反应物的选择性溶剂化[4]和分子水平上的信息存储在机械有机化学中的应用。使用氘代均三甲苯作为溶剂的胶囊中的异丙基氯ClCH（CH 3）2的NMR光谱如图2 a所示。均三甲苯太大而不能包封，并且不能与以较低浓度存在的适当大小的客体竞争。因此，光谱表示阵列1。在两个位置的客人的尖锐，广泛分离的信号反映了相当大的能量障碍，防止客人分子交换位置：它们太大了，而在胶囊内无法相互滑过。交换过程的速率在NMR时间尺度上是缓慢的。通过NOE实验证实了分配。照射高场双峰得到NOE，
Isomers in chemistry are defined through constitution. Further stereochemical relationships between two molecules can be assigned through configuration and conformation, but collections of molecules can also show isomerism through their arrangements in space. We report here a new form of isomerism resulting from the encapsulation of three small-molecule guests in a cylindrical, reversibly assembled host. The mobility of the guests within the host is limited: the guest molecules are held in different constellations within the confined space. The various combinations and isomeric constellations of capsules are nanoscale data storage devices. Encapsulation complexes are reversibly formed assemblies in which small-molecule guests are surrounded by a multimolecular host. The systems are held together by weak intermolecular forces comprising metal±ligand interactions and hydrogen bonding. The assemblies are dynamic; they form and dissipate on time scales ranging from milliseconds to hours. The mechanical barriers that constrain the molecules within molecules offer new possibilities for isomerism, first observed in covalently bound carcerands.[1] In reversibly bound encapsulation complexes,[2] the lifetime of the array is determined by the mobility of the guests, either within the capsule or through exchange with molecules outside, in solution. We report here isomeric constellations–arrangements of several molecules in space–that emerge when two different guests, are encapsulated within a cylindrical host.[3] Specifically, all combinations of chloroform and isopropyl chloride in the encapsulation complexes (Figure1) can be identified by NMR methods. The isomerism is an emergent property of the assembly, rather than that of individual molecules. The phenomenon hints at applications in mechanistic organic chemistry through the selective solvation of reactants [4] and information storage at the molecular level.The NMR spectrum of isopropyl chloride ClCH (CH3) 2 in the capsule using deuterated mesitylene as the solvent is shown in Figure 2 a. Mesitylene is too large to be encapsulated and cannot compete with appropriately sized guests present at lower concentrations. Accordingly, the spectrum represents array 1. The sharp, widely separated signals for guests in the two locations reflect the sizable energetic barrier that prevents the guest molecules from exchanging positions: they are too large to slip past each other while within the capsule. The rate of the exchange process is slow on the NMR time scale. The assignments were confirmed by NOE experiments. Irradiation of the upfield doublet gave NOEs with the