Self-assembly processes of octahedron-shaped Pd<sub>6</sub>L<sub>12</sub> cages

Komine, Shohei; Tateishi, Tetsuya; Kojima, Tatsuo; Nakagawa, Haruna; Hayashi, Yujiro; Takahashi, Satoshi; Hiraoka, Shûichi

doi:10.1039/c8dt04931a

Cited by 12 publications

(13 citation statements)

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“…These additives can open an alternative formation pathway proceeding through ML x –1 Cl intermediates, which was shown to provide spheres at lower temperatures than typically required (Figure ). This pathway is in accordance with the recently reported pathway using 2-chloropyridine. , However, catalytic amounts of halides have shown to be sufficient (in contrast, 2-chloropyridine is used superstoichiometrically).…”

Section: Results and Discussionsupporting

confidence: 92%

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Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

2021

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The dynamics of metal organic polyhedra (MOP) play a crucial role for their application in catalysis and host–guest chemistry and as functional materials. In this contribution, we study the influence of possible contaminations of different metal precursors on the kinetic properties of MOP. Exemplary five different MOP are studied with metal precursors of varying quality. The metal precursors are either obtained from commercial sources or prepared by various literature procedures. Studies into the self-assembly process using 1 H NMR and MS analyses were performed on Pt 2 L 4 , Pd 2 L 4 , Pd 6 L 12 , Pd 12 L 24 , and Ni 4 L 6 assemblies. Commonly found impurities are shown to play a prominent role guiding selective formation of MOP, as they allow for an escape from otherwise kinetically trapped intermediates. The energy requirement for selective sphere formation is significantly lowered in many examples providing evidence for a catalytic role of halide impurities/additives in the self-assembly process. Furthermore, even though most analytical features such as 1 H NMR and MS analyses show identical results for assemblies with different types of metal precursors, the dynamics of formed assemblies differs significantly if slightly less pure starting materials are used. Tiny amounts of halide contaminations make the MOP more dynamic, which can play an important role for substrate diffusion especially if bulky substrates are used. We believe that this study on the influence of impurities (which were shown to be present in some commercial sources) on the kinetic properties of MOP together with procedures of obtaining high purity metal precursors provides important information for future material preparation and provides a better understanding of already known examples.

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Section: Results and Discussionsupporting

confidence: 92%

“…This pathway is in accordance with the recently reported pathway using 2-chloropyridine. 44,45 However, catalytic amounts of halides have shown to be sufficient (in contrast, 2-chloropyridine is used superstoichiometrically).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

2021

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“…A similar approach was reported by Severin and Hiraoka based on clathrochelate metallo-ligands. 55,56 We now show that combining lean ligand L A and bulky derivative L B opens a new strategy to form unprecedented [Pd 4 L A 4 L B 4 ] heteroleptic structures. Key to clean, integrative self-sorting is the presence of two non-equivalent edge types in the [Pd 4 L 8 ] tetrahedron, combined with control over steric pressure in the ligand backbones.…”

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confidence: 87%

Integrative Assembly of Heteroleptic Tetrahedra Controlled by Backbone Steric Bulk

et al. 2021

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A bent fluorenone-based dipyridyl ligand L A reacts with Pd II cations to a solvent-dependent dynamic library of [Pd n L 2 n ] assemblies, constituted by a [Pd 3 L A 6 ] ring and a [Pd 4 L A 8 ] tetrahedron as major components, and a [Pd 6 L A 12 ] octahedron as minor component. Introduction of backbone steric hindrance in ligand L B allows exclusive formation of the [Pd 6 L B 12 ] octahedron. Combining equimolar amounts of both ligands results in integrative self-sorting to give an unprecedented [Pd 4 L A 4 L B 4 ] heteroleptic tetrahedron. Key to the non-statistical assembly outcome is exploiting the structural peculiarity of the [Pd 4 L 8 ] tetrahedral topology, where the four lean ligands occupy two doubly bridged edges and the bulky ligands span the four remaining, singly bridged edges. Hence, the system finds a compromise between the entropic drive to form an assembly smaller than the octahedron and the enthalpic prohibition of pairing two bulky ligands on the same edge of the triangular ring. The emission of luminescent L A is maintained in both homoleptic [Pd 3 L A 6 ] and heteroleptic [Pd 4 L A 4 L B 4 ].

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“…The formation of architecturally complex polyhedral coordination cages from a combination of labile metal ions and simple organic bridging ligands has continued to fascinate supramolecular chemists for quite a few decades now. − One of the more powerful strategies for the efficient synthesis of such supramolecular assemblies involves the use of well-arranged polyhedral building units (PBUs) in combination with suitable linker motifs, leading to self-assembled cages with specifically desired geometries and functions. , Thus, cages with cationic, anionic, and neutral frameworks can be synthesized by selecting appropriate PBU precursors and linker ligands. , Apart from the topological feasibilities, , the reactivities of the participating moieties also determine the pathway and, consequently, the product formation in the molecular self-assembly. − The concentration of the reactants, − external stimuli, − reaction templates, − post-assembly transformations, − etc. are some of the most important factors that affect the component reactivity and the formation of suitable products.…”

Section: Introductionmentioning

confidence: 99%

Mapping the Assembly of Neutral Tetrahedral Cages Tethered by Oximido Linkers and Their Guest Encapsulation Studies

Sarkar

Boomishankar

2022

Inorg. Chem.

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A primary criterion for the design of polyhedral metal− organic cages is the requirement of geometrically matched pairs of metal ions and ligand moieties. However, understanding the pathway it takes to reach the final polyhedral structure can provide more insights into the self-assembly process and improved design strategies. In this regard, we report two neutral tetrahedral cages with the formulas {[Pd 3 (N i Pr) 3 PO] 4 (L 1 ) 6 } (1-TD) and {[Pd 3 (N i Pr) 3 PO] 4 (L 2 ) 6 } (2-TD) s t a r t i n g f r o m t h e a c e t a t e -b r i d g e d c l u s t e r). When subtle variations in the reaction conditions w e r e m a d e , t w o n e w t e t r a m e r i c P d 1 2 a s s e m b l i e s , { [ P d 3 ( N i P r) 2 (OAc) 4 (OMe) 4 } (2-TM), were obtained from the same precursors. Detailed investigations using NMR, mass spectrometry, X-ray crystallography, and computational studies indicate that the macrocyclic complexes 1-TM and 2-TM are the reaction intermediates involved in the formation of the tetrahedral cages 1-TD and 2-TD, respectively. Moreover, the tetrahedral cages 1-TD and 2-TD exhibited intrinsic cavities of volume ∼85 Å 3 . Guest encapsulation studies revealed that the cage 1-TD can encapsulate a wide range of guest molecules such as CH 2 Cl 2 , CHCl 3 , CCl 4 , C 6 H 6 , and C 6 H 5 F. Interestingly, 1-TD was shown to exhibit a preferential binding of C 6 H 5 F and C 6 H 6 over other halogenated guest molecules, as determined from NMR titrations and computational studies.

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Self-assembly processes of octahedron-shaped Pd₆L₁₂ cages

Abstract: Self-assembly processes of three octahedron-shaped [Pd6L12]12+ cages were investigated by an NMR-based quantitative approach (QASAP).

Cited by 12 publications

References 56 publications

Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

Integrative Assembly of Heteroleptic Tetrahedra Controlled by Backbone Steric Bulk

Mapping the Assembly of Neutral Tetrahedral Cages Tethered by Oximido Linkers and Their Guest Encapsulation Studies

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Self-assembly processes of octahedron-shaped Pd6L12 cages

Abstract: Self-assembly processes of three octahedron-shaped [Pd6L12]12+ cages were investigated by an NMR-based quantitative approach (QASAP).

Cited by 12 publications

References 56 publications

Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

Catalytic Formation of Coordination-Based Self-Assemblies by Halide Impurities

Integrative Assembly of Heteroleptic Tetrahedra Controlled by Backbone Steric Bulk

Mapping the Assembly of Neutral Tetrahedral Cages Tethered by Oximido Linkers and Their Guest Encapsulation Studies

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Self-assembly processes of octahedron-shaped Pd₆L₁₂ cages