Dendrimer Complexes Based on Fine-Controlled Metal Assembling

Yamamoto, Kimihisa; Imaoka, Takane

doi:10.1246/bcsj.79.511

Cited by 41 publications

(41 citation statements)

References 140 publications

(128 reference statements)

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“…In our previous study, a DPA with a monosubstituted phenyl group as core also exhibited similar stepwise complexation starting from the core. [16] It is likely that stepwise complexation is a characteristic property of the dendritic phenylazomethine block. Distortion of the inherent property gradient based on the electron density or donor strength should be due to the bent conformation toward the vacant space around the core unit.…”

Section: Discussionmentioning

confidence: 99%

“…This would lead to a system with a polydispersemetal-assembled structure in a monodisperse macromolecular ligand. [16] Since the discovery of stepwise radial complexation in a dendritic polyphenylazomethine (DPA), [17] variations of this molecule were synthesized. [18][19][20][21][22][23][24][25] The DPA family of macromolecular ligands has a unique metal-assembling process in which metal ions bind to the branching monomer units in perfect order from the core to the outside termini.…”

Section: Introductionmentioning

confidence: 99%

“…One of the principal driving forces for stepwise assembly may be a steep basicity gradient through the dendritic cascade structure, based on the strong electron-donating effect of the phenylazomethine building blocks stacked on the outer connections. [16] In addition, it is likely that the rigid p-conjugated structure is indispensable for the unique metal-assembling property. Dendrimers with a flexible backbone tend to exhibit many conformations including backfolding of the terminal monomers into the core even at room temperature.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of a Molecular Morphology Effect on Polyphenylazomethine Dendrimers; Physical Properties and Metal‐Assembling Processes

Imaoka

Tanaka

Yamamoto

2006

Chemistry A European J

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A series of novel dendritic polyphenylazomethines (DPA) with asymmetric morphologies was synthesized. Their physical properties, such as encapsulating effect, molecular dynamics, and metal assembly, are strongly dependent on the entire conformation of the molecules. The most important property is layer-by-layer metal assembly in the dendrimer structure from the core to the outside. Bis- and tris-substituted DPAs of the fourth generation also act as frameworks for stepwise assembly of a metal component (SnCl2), like the fully substituted symmetric DPA. However, extensive investigation of metal assembly in specific DPAs revealed that they do not follow the stepwise process. The molecular density calculated from the experimental hydrodynamic volume indicated that bis- and tris-substituted DPAs with asymmetric morphology still retain a free space similar to that of fully substituted symmetric DPA. The monosubstituted DPA, however, displayed a slightly higher density (smaller space) than the other DPAs. The experimental results suggest a bent conformation of the dendrimer in which the core moiety is folded into the dendron structure. In addition, the molecular dynamics were probed by means of the 1H NMR signals of the porphyrin core. It was demonstrated that the conformation is not fixed at room temperature in solvated DPAs, especially in monosubstituted DPA. A similar observation was for the smaller DPAs (third generations) with asymmetric morphologies. These dendrimers do not follow the stepwise complexation process. The structures of bis- and tris-substituted dendrimers which accurately follow the stepwise process are fixed. These observations provide a new insight into the finely controlled metal-assembly chemistry of dendritic macromolecules, and a rigid and fixed conformation is one of important factors for their unique properties.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of a Molecular Morphology Effect on Polyphenylazomethine Dendrimers; Physical Properties and Metal‐Assembling Processes

Imaoka

Tanaka

Yamamoto

2006

Chemistry A European J

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“…[118] Recently, Yamamoto and colleagues reported that metalassembling dendritic phenylazomethines could also significantly improve the electron transfer reaction as a protein-like catalyst. [119] Later the same group showed that the lanthanide-ion-assembling dendritic phenylazomethines with a cobalt porphyrin core may also act as an efficient catalyst for the CO 2 electrochemical reduction with a very low potential. [120] Cobalt tetraphenylporphyrin, which is a model of the core unit, is known to catalyse the reduction.…”

Section: Dendrimers In Photodynamic Therapymentioning

confidence: 99%

Dendrimers as therapeutic agents: a systematic review

et al. 2009

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Objectives Dendrimers by virtue of their therapeutic value have recently generated enormous interest among biomedical scientists. This review describes the therapeutic prospects of the dendrimer system. Key findings Their bioactivity suggests them to be promising therapeutic agents, especially in wound healing, bone mineralisation, cartilage formation and tissue repair, and in topical treatments to prevent HIV transmission. Findings also demonstrate their potential as anti-prion, anti-Alzheimer's, anticoagulant, antidote, anti-inflammatory and anticancer agents. One of the dendrimer-based formulations with activity against herpes simplex virus (VivaGel from Starpharma) has successfully completed phase I clinical trials and is expected to be available on the market soon. Summary All reports cited in this review demonstrate the use of dendrimers as medical therapeutics in different ailments. The review focuses on the current state of therapeutic potential of the dendrimer system.

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“…Phenylazomethine dendrimers composed of rigid p-conjugated backbones exhibit exceptionally fine coordination processes, such as step-by-step assembly [29][30][31] , allowing one-atom controlled synthesis of metal clusters 32 . In addition, previous studies have shown that the stable quadrupole character of such dendrimers allows an efficient photoelectric process based on their rectification properties 33 .…”

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confidence: 99%

Macromolecular semi-rigid nanocavities for cooperative recognition of specific large molecular shapes

et al. 2013

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Molecular shape recognition for larger guest molecules (typically over 1 nm) is a difficult task because it requires cooperativity within a wide three-dimensional nanospace coincidentally probing every molecular aspect (size, outline shape, flexibility and specific groups). Although the intelligent functions of proteins have fascinated many researchers, the reproduction by artificial molecules remains a significant challenge. Here we report the construction of large, well-defined cavities in macromolecular hosts. Through the use of semi-rigid dendritic phenylazomethine backbones, even subtle differences in the shapes of large guest molecules (up to B2 nm) may be discriminated by the cooperative mechanism. A conformationally fixed complex with the best-fitting guest is supported by a three-dimensional model based on a molecular simulation. Interestingly, the simulated cavity structure also predicts catalytic selectivity by a ruthenium porphyrin centre, demonstrating the high shape persistence and wide applicability of the cavity.

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Dendrimer Complexes Based on Fine-Controlled Metal Assembling

Cited by 41 publications

References 140 publications

Investigation of a Molecular Morphology Effect on Polyphenylazomethine Dendrimers; Physical Properties and Metal‐Assembling Processes

Investigation of a Molecular Morphology Effect on Polyphenylazomethine Dendrimers; Physical Properties and Metal‐Assembling Processes

Dendrimers as therapeutic agents: a systematic review

Macromolecular semi-rigid nanocavities for cooperative recognition of specific large molecular shapes

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