Stereochemical Communication within Tetrahedral Capsules

Ramsay, William J.; Nitschke, Jonathan R.

doi:10.1246/cl.131048

Cited by 50 publications

(22 citation statements)

References 89 publications

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“…5). [34][35][36][37] In most cases these appear to be composed of four self selecting fac orientated metal centres, either templated around an appropriate counter ion, or through favourable π-stacking interactions.…”

Section: Polynuclear Assembliesmentioning

confidence: 99%

“…With more labile metal centres, such as iron(II), cobalt(II) and zinc(II), the matter has not perhaps been as readily accessible until recently where the aggregation of these simple units into large supramolecular assemblies such as helicates, [30][31][32][33] tetrahedral capsules [34][35][36][37] and even larger units 38 can require the selective organization of these units into the statistically less favoured fac isomer. Further, the packing and relative orientation of the mer and fac geometry in iron(II) complexes in the solid-state for application as spin-crossover species appears to be critical to the all important transition temperatures.…”

Section: Introductionmentioning

confidence: 99%

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mer and fac isomerism in tris chelate diimine metal complexes

Dabb

Fletcher

2015

Dalton Trans.

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In this perspective, we highlight the issue of meridional (mer) and facial (fac) orientation of asymmetrical diimines in tris-chelate transition metal complexes. Diimine ligands have long been the workhorse of coordination chemistry, and whilst there are now good strategies to isolate materials where the inherent metal centered chirality is under almost complete control, and systematic methodologies to isolate heteroleptic complexes, the conceptually simple geometrical isomerism has not been widely investigated. In systems where the two donor atoms are significantly different in terms of the σ-donor and π-accepting ability, the fac isomer is likely to be the thermodynamic product. For the diimine complexes with two trigonal planar nitrogen atoms there is much more subtlety to the system, and external factors such as the solvent, lattice packing and the various steric considerations play a delicate role in determining the observed and isolable product. In this article we discuss the possibilities to control the isomeric ratio in labile systems, consider the opportunities to separate inert complexes and discuss the observed differences in their spectroscopic properties. Finally we report on the ligand orientation in supramolecular systems where facial coordination leads to simple regular structures such as helicates and tetrahedra, but the ability of the ligand system to adopt a mer orientation enables self-assembled structures of considerable beauty and complexity.

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Section: Polynuclear Assembliesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mer and fac isomerism in tris chelate diimine metal complexes

Dabb

Fletcher

2015

Dalton Trans.

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“…cages.41−44 Our research on the transfer of stereochemical information between vertices of polyhedra has focused on M 4 L 6 tetrahedral cages, because they have been observed to exhibit the richest stereochemistry 32,45. Depending on the Λ or Δ configuration of each metal center, a tetrahedral ensemble (M 4 L 6 or M 4 L 4 ) can adopt homochiral T (ΛΛΛΛ/ΔΔΔΔ), heterochiral C 3 (ΔΔΔΛ/ΛΛΛΔ), or achiral S 4 (ΛΛΔΔ) overall symmetry, as shown in…”

mentioning

confidence: 99%

“…Subcomponent self-assembly and crystal structure of barrel-like structures (a) Co 10 L 15(32), showing encapsulated PF 6 − and Cl − , and (b) Fe 10 L 15(34).…”

mentioning

confidence: 99%

Stereochemistry in Subcomponent Self-Assembly

2014

Self Cite

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CONSPECTUS: As Pasteur noted more than 150 years ago, asymmetry exists in matter at all organization levels. Biopolymers such as proteins or DNA adopt one-handed conformations, as a result of the chirality of their constituent building blocks. Even at the level of elementary particles, asymmetry exists due to parity violation in the weak nuclear force. While the origin of homochirality in living systems remains obscure, as does the possibility of its connection with broken symmetries at larger or smaller length scales, its centrality to biomolecular structure is clear: the single-handed forms of bio(macro)molecules interlock in ways that depend upon their handednesses. Dynamic artificial systems, such as helical polymers and other supramolecular structures, have provided a means to study the mechanisms of transmission and amplification of stereochemical information, which are key processes to understand in the context of the origins and functions of biological homochirality. Control over stereochemical information transfer in self-assembled systems will also be crucial for the development of new applications in chiral recognition and separation, asymmetric catalysis, and molecular devices. In this Account, we explore different aspects of stereochemistry encountered during the use of subcomponent self-assembly, whereby complex structures are prepared through the simultaneous formation of dynamic coordinative (N → metal) and covalent (N═C) bonds. This technique provides a useful method to study stereochemical information transfer processes within metal-organic assemblies, which may contain different combinations of fixed (carbon) and labile (metal) stereocenters. We start by discussing how simple subcomponents with fixed stereogenic centers can be incorporated in the organic ligands of mononuclear coordination complexes and communicate stereochemical information to the metal center, resulting in diastereomeric enrichment. Enantiopure subcomponents were then incorporated in self-assembly reactions to control the stereochemistry of increasingly complex architectures. This strategy has also allowed exploration of the degree to which stereochemical information is propagated through tetrahedral frameworks cooperatively, leading to the observation of stereochemical coupling across more than 2 nm between metal stereocenters and the enantioselective synthesis of a face-capped tetrahedron containing no carbon stereocenters via a stereochemical memory effect. Several studies on the communication of stereochemistry between the configurationally flexible metal centers in tetrahedral metal-organic cages have shed light on the factors governing this process, allowing the synthesis of an asymmetric cage, obtained in racemic form, in which all symmetry elements have been broken. Finally, we discuss how stereochemical diversity leads to structural complexity in the structures prepared through subcomponent self-assembly. Initial use of octahedral metal templates with facial stereochemistry in subcomponent self-assembly, which predic...

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“…其中手性 MOCs更是在立体化学、非线性光学、生物医学以及酶的模拟等领域展现出独特的潜力. 金属-有机分子笼可以通过消除内部的反转对称或者镜像对称来控制几何上的对称性, 从而产生手性 [9] . 手性MOCs与不同组分之间可以实现立体化学的记忆、转移和通信, 从而导致复杂手性体系的协同效应, 进而实现手性识别、 [17] ; 8个三齿的Ru(II)金属配体和6个四配位的Pd…”

Section: 引言unclassified

Assembly and properties of Pd<sub>4</sub>Ru<sub>8</sub> metal-organic cages based on polypyridine Ru(II)-metalloligand

Li¹,

Liu²,

Wang³

et al. 2020

Sci. Sin.-Chim

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摘要本文以Ru(II)的多吡啶金属配合物[Ru(bpy) 2 (qpy)(BF 4) 2 ](qpy=4,4′:2′,2′′:4′′,4′′′-四吡啶, bpy=2,2′-联吡啶) 作为金属配体与平面四配位的Pd 2+ 进行二次配位自组装, 得到一例较为罕见的Pd 4 Ru 8 型金属-有机分子笼rac-MOC-52. 通过X射线单晶衍射确定了分子笼的空间结构, 发现该类分子笼为缺上下底面的、类似柱状的立方体结构. 进一步通过诱导预拆分方法, 得到了纯手性的Δ/Λ-[Ru(bpy) 2 ] 2+

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Stereochemical Communication within Tetrahedral Capsules

Cited by 50 publications

References 89 publications

mer and fac isomerism in tris chelate diimine metal complexes

mer and fac isomerism in tris chelate diimine metal complexes

Stereochemistry in Subcomponent Self-Assembly

Assembly and properties of Pd<sub>4</sub>Ru<sub>8</sub> metal-organic cages based on polypyridine Ru(II)-metalloligand

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Stereochemical Communication within Tetrahedral Capsules

Cited by 50 publications

References 89 publications

mer and fac isomerism in tris chelate diimine metal complexes

mer and fac isomerism in tris chelate diimine metal complexes

Stereochemistry in Subcomponent Self-Assembly

Assembly and properties of Pd&lt;sub&gt;4&lt;/sub&gt;Ru&lt;sub&gt;8&lt;/sub&gt; metal-organic cages based on polypyridine Ru(II)-metalloligand

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Assembly and properties of Pd<sub>4</sub>Ru<sub>8</sub> metal-organic cages based on polypyridine Ru(II)-metalloligand