Fine-tuning the ring-size of metallacyclophanes:: A rational approach to molecular pentagons
Fine-tuning the ring-size of metallacyclophanes:: A rational approach to molecular pentagons
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DOI：
10.1021/ja002960r
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发表时间：
2001-01-31
影响因子：
15
通讯作者：
Dunbar, KR
中科院分区：
文献类型：
--
作者：
Campos-Fernández, CS;Clérac, R;Dunbar, KR
超分子化学的本质是非共价连接的分子簇和网络的自组装，这是一个自发的过程，涉及各种驱动力（例如，金属-配体相互作用，离子模板，氢键，π堆积）和化学柔性（即结构单元的容易重排）。原则上，如果人们能够确定自组装过程中的主导因素，那么它们可以系统地变化以有利于特定的超分子实体。这一原理通过金属阳离子与双螯合配体如bptz（3，6-双（2-吡啶基）1，2，4，5-四嗪）的自组装反应很好地说明。2-4我们在该化学中的早期发现之一是分子正方形[M4（bptz）4（MeCN）8] 8+（M：Ni，Zn）4，5与[BF 4]-和[ClO 4]-以高产率形成，但与阴离子如[PF 6]-、[BPh 4]-和[CF 3SO 3]-不形成。有了这些信息，我们对阴离子在确定金属/bptz反应产物中的作用进行了全面的研究。这些研究的前提是，如果有合适的阴离子作为模板，其他的核性也是有利的。如果考虑常见阴离子的尺寸和形状参数，6 [SbF 6]-与Vm）63 <$3相比，[BF 4]-和[ClO 4]-分别为38和47 <$3，是形成稍大的环状实体的绝佳候选者。基于该前提，使[Ni（CH 3CN）6][SbF 6] 2与bptz以1：1的比例在乙腈中反应（方案1）。
The essence of supramolecular chemistry is the self-assembly of noncovalently linked molecular clusters and networks, a spontaneous process that involves various driving forces (eg, metal-ligand interactions, ion templation, hydrogen bonding, π stacking) and chemical flexibility (ie facile rearrangement of the building blocks). 1 In principle, if one can identify the dominant factors in a self-assembly process, they can be systematically varied to favor specific supramolecular entities. This principle is nicely illustrated by the self-assembly reactions of metal cations with bis-chelating ligands such as bptz,(3, 6-bis (2-pyridyl) 1, 2, 4, 5-tetrazine). 2-4 Among our early findings in this chemistry was that the molecular squares [M4 (bptz) 4 (MeCN) 8] 8+(M: Ni, Zn) 4, 5 form in high yields with [BF4]-and [ClO4]-but not with anions such as [PF6]-,[BPh4]-, and [CF3SO3]-. Armed with this information, we launched a comprehensive investigation into the role of the anion in determining the products of metal/bptz reactions. The premise of the studies was that other nuclearities could be favored, provided the appropriate anion is available to act as a template. If one considers the size and shape parameters of common anions, 6 [SbF6]-with Vm) 63 Å3 compared to 38 and 47 Å3 for [BF4]-and [ClO4]-, respectively, is an excellent candidate for the formation of a slightly larger cyclic entity. On the basis of this premise,[Ni (CH3CN) 6][SbF6] 2 was reacted with bptz in a 1: 1 ratio in acetonitrile (Scheme 1).