Analysis of the Spatial Dimensions of Fully Aromatic Dendrimers

Rosenfeldt, Sabine; Dingenouts, N.; Pötschke, D.; Ballauff, Matthias; Berresheim, Alexander J.; Müllen, Kläus; Lindner, Peter

doi:10.1002/anie.200351810

Cited by 52 publications

(32 citation statements)

References 22 publications

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“…[250,251] Neutron diffraction experiments have shown that they are denser at the periphery than at the core. [252] As a result of this rigidity any two groups within the dendrimer or upon its surface are in well-defined spatial relationships to each other, which is of great importance for controlling their electronic interactions, particularly the transfer of excitation energy between them. It also means that the shape of the empty space between groups in the interior of the dendrimer is well-defined and, as a consequence of the limited mobility of the benzene rings within the structure, relatively invariant, which offers the possibility of manipulating this space by synthetic design so as to produce great selectivity for guest molecules.…”

Section: Dendrimers As Vessels For Chemistry Physics and Biologymentioning

confidence: 99%

The Chemistry of Organic Nanomaterials

2005

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The development of nanotechnology using organic materials is one of the most intellectually and commercially exciting stories of our times. Advances in synthetic chemistry and in methods for the investigation and manipulation of individual molecules and small ensembles of molecules have produced major advances in the field of organic nanomaterials. The new insights into the optical and electronic properties of molecules obtained by means of single-molecule spectroscopy and scanning probe microscopy have spurred chemists to conceive and make novel molecular and supramolecular designs. Methods have also been sought to exploit the properties of these materials in optoelectronic devices, and prototypes and models for new nanoscale devices have been demonstrated. This Review aims to show how the interaction between synthetic chemistry and spectroscopy has driven the field of organic nanomaterials forward towards the ultimate goal of new technology.

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Section: Dendrimers As Vessels For Chemistry Physics and Biologymentioning

confidence: 99%

The Chemistry of Organic Nanomaterials

2005

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“…[21][22][23][24] In general, dendrimers bearing rigid -conjugating backbones are known to have a dense shell and a sparse core. 25,26 The nano-space around the core unit is utilized as a molecular-capsule for capturing metal ions, [27][28][29][30][31][32][33] clusters, [34][35][36][37][38][39][40][41][42] or other guest molecules. 43,44 The dendrimers can manage electron [45][46][47] or energy [48][49][50][51][52][53][54][55][56][57][58] transfer between the core and the periphery due to their unique density-gradated architecture.…”

Section: Metallo-dendrimer Complexesmentioning

confidence: 99%

“…A design strategy for such an unusual system is to utilize the unique dense shell property of rigid dendrimers. 25,26 All dendrimers reported as ligands for multi-metal ion assemblies have flexible backbones composed of single covalent () bonds. However, they are not suitable for precise metal assembly because their conformational changes and back-folding with thermal vibrations would prevent the precise discrimination of the coordination sites.…”

Section: Fine-controlled Metal Assembling In Dpas (Dendritic Phenylazmentioning

confidence: 99%

Dendrimer Complexes Based on Fine-Controlled Metal Assembling

Yamamoto¹,

Imaoka²

2006

Bulletin of the Chemical Society of Japan

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A series of novel dendrimers composed of dendritic phenylazomethines (DPAs) were synthesized with several types of functional cores. The metal assembling to the DPAs is stepwise by the layers, therefore, they can be used as a scaffold for the precise hybridization between metal ions and organic macromolecules. Because of uniform structure of the dendrimer, there is no structural dispersion in the macromolecule-metal hybrid of the DPAs. Also, the number of metal ions loaded in one dendrimer should have no statistical distribution in principle due to the precise metal assembling. A rigid -conjugating backbone structure contributes not only to the stepwise metal assembly, but also to the solid-state stability under high temperature. Development of this property without any reduction in solubility in organic media enabled the easy preparation of homogeneous amorphous films in which the metal and macromolecule are precisely hybridized. As a result, the thin solid of the metal-assembling dendrimer acts as an excellent organic semiconductor in the hole-transport layer of a light-emitting diode. Metal-assembling DPAs also enhance the electron-transfer reaction as a protein-like catalyst. The DPA having a cobalt porphyrin core-could catalyze the CO 2 reduction at an applied overpotential 1.1 V lower than that needed for the catalysis by a model compound of the porphyrin core (CoTPP). Reversible encapsulation/release of multiple irons is also demonstrated as a mimic of the iron storage protein (Ferritin). The switching between these two coordinating states can be completely controlled by the redox states of the iron (Fe II / Fe III ). The finding of these unique dendritic ligands will afford new insight into molecular design for finely controlled macromolecule-metal hybrid materials. Metallo-Dendrimer ComplexesMacromolecule-metal complexes 1 are defined as molecularlevel hybrids built up with metal complexes and organic polymers. They have been noted in evolution of novel functions based on synergetic effect between the functionality of each part (metal and polymer). For example, applications of these materials for fixation of catalysts, 2 functional modified electrodes based on electron [3][4][5] /ion 6 conductivity, electron-spin control, 7 and amplification of photoelectron conjugating properties 8 demonstrate outstanding enhancement. Most of them are induced by (1) supporter effect, (2) concentration/dilution effect, (3) environmental effect, (4) conformational effect, and (5) cooperative/concerted effect by micro domains in the polymers. For maximum use of these domains, a general methodology that can handle the higher-order structure of the hybrids is strongly required. All the molecular, hybrid, and higher-order structures of the conventional macromolecule-metal complexes are however dispersed with statistical distribution, and impossible to fix themselves into one limited form. Now many research interest moved to the next stage focusing on the control of higher-order structures using self-assembling approach based...

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“…[3] In Konsequenz wird die räumliche Form der PPDs durch die Geometrie ihres Kerns vorgegeben, sodass allein durch die Verwendung von unterschiedlichen Kernmotiven (Abbildung 1 a-c) vielfältige Dendrimerstrukturen erhalten werden können. [4] Zur Synthese möglichst kugelförmiger Strukturen konnten bislang nur vierarmige Tetraederkerne (Tetraphenylmethan, Abbildung 1 c) eingesetzt werden, [5] da höhere Symmetrien, wie beispielsweise die eines Oktaeders, mit den Mitteln der organischen Synthesechemie nur schwer zu generieren sind.…”

Section: Professor Klaus Hafner Zum 80 Geburtstag Gewidmetunclassified

“…Demgegenüber ermöglicht die metallorganische Chemie die Herstellung von Koordinationsverbindungen mit höheren Symmetrien. Ein Beispiel ist der bekannte Tris(2,2'-bipyridyl)ruthenium(II)-Komplex ([Ru(bpy) 3 ], Abbildung 1 d), [6] der sich bereits als Kern für nicht formstabile Dendrimere bewährt hat. [7][8][9] Ziel dieser Studien war es meist, den Einfluss dendritischer Hüllen auf die Eigenschaften des Ruthenium-Chromophors zu untersuchen [8] oder molekulare Lichtsammelsysteme zu generieren.…”

Section: Professor Klaus Hafner Zum 80 Geburtstag Gewidmetunclassified