The self-assembly process of a PdL double-walled square (DWS) was investigated. As was seen in PdL cages, Pd(II)-linked coordination self-assembly processes are generally affected by the rigidity of multitopic ligands. However, the self-assembly of a PdL DWS from rigid ditopic ligands took place with the formation of two kinds of metastable species [submicrometer-sized species and a PdL double-walled triangle (DWT)].
View Article and Find Full Text PDFAn NMR-based quantitative analysis of self-assembly process (QASAP) for the self-assembly of a Pd3L6 double-walled triangle (DWT) from PdPy*4(BF4)2 (Py* indicates 3-chloropyridine) and V-shaped ditopic ligands (L) revealed that DWT was assembled through trinuclear single-walled chains, in which the intramolecular macrocyclization and the formation of double-walls took place leading to the final assembly.
View Article and Find Full Text PDFThe chiral self-sorting process during the self-assembly of homochiral PdL capsules from cyclotriveratrylene (CTV)-based chiral tritopic ligands (L) and (Py*: 3-chloropyridine) was investigated by an NMR-based approach (QASAP: quantitative analysis of the self-assembly process). From the beginning to the formation of the immature capsules (s), enantiomeric ligands are distributed in the intermediates in a non-self-sorting manner, which leads to the isomers of heterochiral s over 99% yield. The mismatch of the chirality in the heterochiral s prevents intramolecular ligand exchanges in s to form the heterochiral capsules.
View Article and Find Full Text PDFA kinetic trap is the metastable species that is transiently or constantly produced during the reaction by trapping in a deep energy well. In most cases, the reactivity of kinetically trapped species is relatively low under the reaction conditions. Herein, we report another type of kinetically trapped species that is an incomplete cage (IC) intermediate produced during the self-assembly of a Pd L cage from ditopic ligand (L) and Pd ions with a certain lifetime, although IC has a high enough reactivity to be converted into the cage with the reaction of free L, which was confirmed by the reaction of the isolated IC and L under the self-assembly conditions.
View Article and Find Full Text PDFThe self-assembly process of a PdL cage consisting of flexible ditopic ligands and Pd(ii) ions was revealed by QASAP (quantitative analysis of self-assembly process), which enables one to obtain information about the intermediates transiently produced during the self-assembly as the average composition of all the intermediates. It was found that the dominant pathway to the cage is the formation of a submicrometre-sized sheet structure, which was characterized by dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM), followed by the addition of free ditopic ligands to the Pd(ii) centres of the sheet structure to trigger the cage formation. This assembly process is completely different from that of a PdL cage composed of rigid ditopic ligands, indicating that the flexibility of the components strongly affects the self-assembly process.
View Article and Find Full Text PDFThe effect of molecular interactions between the components on the self-assembly process of Pd L structures was investigated by a H NMR-based quantitative approach (QASAP: quantitative analysis of self-assembly process). Although the self-assembly of the Pd L cage without interactions between the bent ligands took place, mainly producing small intermediates, the self-assembly of the Pd L capsule composed of bent ligands with anthracene panels tends to produce large intermediates containing more components than the capsule. This is ascribed to steric interactions between the panels.
View Article and Find Full Text PDFThe self-assembly process of a Pd L sphere was revealed by a quantitative approach (quantitative analysis of self-assembly process: QASAP) quantifying all the substrates, the products, and the observable intermediates, indicating that the Pd L sphere is produced through several pathways. Firstly, Pd L (n=6, 8, and 9), which are perfectly closed structures smaller than the Pd L sphere, and a mixture of intermediates not observed by NMR (Int) were produced. Next, the sphere was assembled from intra-/intermolecular reaction of a certain class of Int (path A) and from the coordination of free pyridyl groups in Int to the Pd center of Pd L (n=6, 8, and 9) (path B).
View Article and Find Full Text PDFThe self-assembly process of a Pd L cage complex consisting of rigid ditopic ligands, in which two 3-pyridyl groups are connected to a benzene ring through acetylene bonds and Pd ions was revealed by a recently developed quantitative analysis of self-assembly process (QASAP), with which the self-assembly process of coordination assemblies can be investigated by monitoring the evolution with time of the average composition of all the intermediates. QASAP revealed that the rate-determining steps of the cage formation are the intramolecular ligand exchanges in the final stage of the self-assembly: [Pd L Py* ] →[Pd L Py* ] +Py* and [Pd L Py* ] →[Pd L ] +Py* (Py*: 3-chloropyridine, which was used as a leaving ligand on the metal source). The energy barriers for the two reactions were determined to be 22.
View Article and Find Full Text PDFThe effect of reaction environment on the self-assembly process of an octahedron-shaped PdL capsule was investigated. Quantitative analysis of self-assembly process with H NMR spectroscopy revealed that the self-assembly pathway of the capsule was altered by solvent and a leaving ligand coordinating to the metal source, which are not the components of the final self-assembly. Solvents definitively determine the pathway of the self-assembly at a very early stage of the self-assembly.
View Article and Find Full Text PDFThe racemic ligands (±)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (±)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemble with racemic (Λ,Δ)-[Ir(ppy) (MeCN) ] , in which ppy=2-phenylpyridinato, to form [{Ir(ppy) } (L) ] metallo-cryptophane cages. The crystal structure of [{Ir(ppy) } (L1) ]⋅3BF has MM-ΛΛΛ and PP-ΔΔΔ isomers, and homochiral self-sorting occurs in solution, a process accelerated by a chiral guest. Self-recognition between L1 and L2 within cages does not occur, and cages show very slow ligand exchange.
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