A Dendrimer-Based Electron Antenna:  Paired Electron-Transfer Reactions in Dendrimers with a 4,4‘-Bipyridine Core and Naphthalene Peripheral Groups

Ghaddar, Tarek H.; Wishart, James F.; Thompson, David W.; Whitesell, James K.; Fox, Marye Anne

doi:10.1021/ja020103c

Cited by 87 publications

(58 citation statements)

References 35 publications

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“…Dendrimers have attracted great attention in recent years because of their highly branched and symmetric structure, which can be utilized for various applications including guest-host chemistry, [1] analytical chemistry, [2] optical data storage, [3,4] and medical applications. [5] In addition, dendrimers have been proposed as light-harvesting (LH) antennas, designed to be part of more complex systems for artificial photosynthesis, because of their capability of directional excitation energy transfer (EET).…”

Section: Introductionmentioning

confidence: 99%

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

et al. 2007

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We report a study of the electronic energy-transfer dynamics within the transition-metal polypyridine complex OsRu3pyr6 (Os[(dpp)Ru(bpy{pyrene})2]3(8+), where dpp=2,3-bis(2'-pyridyl)pyrazine and bpy=2,2'-bipyridine) after excitation with UV light. By using a broadband visible femtosecond probe, we are able to simultaneously detect both the energy transfer from the peripheral aromatic ligands to the Os center and the sub-picosecond energy transfer from the initially excited Ru-bpy ligand-centered state to the Os triplet metal-to-ligand charge-transfer (MLCT) state. Pyrene energy transfer occurs from both the nonrelaxed and the relaxed S(1) states on timescales of 6 and 45 ps, respectively. In both cases, the energy transfer is described by means of Förster energy transfer theory. Sub-picosecond energy transfer within the OsRu3 metal-ligand core most likely includes a direct energy transfer between the higher-lying ligand-centered states on Ru and Os, in addition to the transfer between the MLCT states. The absorption cross-sections in both the UV and the visible spectral regions are enhanced by attaching the aromatic pyrene ligands. Furthermore, energy transfer is directed only towards the Os core, which ultimately leads to an exclusive population of the Os-based triplet MLCT state, thus making the OsRu3pyr6 transition metal-polypyridine dendrimer an obvious candidate for artificial light-harvesting systems.

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Section: Introductionmentioning

confidence: 99%

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

et al. 2007

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“…A central methylviologen unit was connected via benzyl spacers to peripheral naphthalene units in dendritic molecular structures. [31] In the system shown in Fig. 4, 16 naphthyl groups are linked to a single methyl viologen unit via 14 benzyl spacers.…”

Section: A Few Specific Case Studies Of Photoinduced Charge Accumulationmentioning

confidence: 99%

Photoinduced Charge Accumulation in Molecular Systems

Bonn

Wenger²

2015

Chimia

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Fuel-forming reactions such as CO 2 reduction or water splitting require multiple redox equivalents. When aiming at light-driven production of energy-rich chemicals, nowadays often referred to as solar fuels, it therefore becomes important to master the photoinduced accumulation of electrons or holes on individual molecular components. Featured in this short review are some of the key molecular systems explored in this emerging field of research. This includes for example a trinuclear Ru(ii)-Rh(iii)-Ru(iii) complex or an Ir(iii)-sensitized polyoxotungstate hybrid, but also several systems in which electron or hole collection occurs at organic moieties such as perylenebis(dicarboximide), quinone-containing or oligotriarylamine-based units. In many cases the photodriven accumulation of charge requires the use of sacrificial electron donors, but there exist also a handful of studies in which redox equivalents can be accumulated without the use of such additives.

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“…[74][75][76][77][78][79] Utilization of the dendrimer framework to encapsulate acceptor moieties c.f. viologen 80,81 and norbornadiene, 82 or donor units such as ruthenium bipyridine complex and anthracene 84 have also been reported for the construction of electron transfer systems. A further extension of using dendrimers for triggering photoinduced electron transfer is to employ photoactive units as the building blocks in the framework.…”

Section: Other Dendritic Pet Systemsmentioning

confidence: 99%

Dendritic Architectures for Design of Photo– and Spin–Functional Nanomaterials

Ishizuka

Jiang

2007

Polym J

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ABSTRACT:Unlike ordinary linear polymers, dendritic architecture is unique in the terms of its elaborative capability for total control over molecular design parameters at the single molecular level, i.e., molecular size, branching pattern, structure, and morphology, thereby provides a new platform for the creation of functional materials with nanometer-scale precision. This review mainly concerns recent works on the development of dendritic nanomaterials with a focus on photo-and spin-related functionalities. Strategy for the incorporation of chromophores to build up light-harvesting antennae is presented with an emphasis on morphology and size effects. Dendritic macromolecules for photoinduced electron transfer are categorized based on chromophores that serve as the active center to absorb light and trigger photochemical process. In this context, dendrimers bearing porphyrin, conjugated polymer, and fullerene for realization of long-lived charge-separation state and light energy conversion are highlighted. On the other hand, design of dendritic macromolecules for spin-functional materials is focused on dendronized organic radicals and dendritic coordination polymers. Especially, spin-functional soft materials with an aim for spin manipulation and novel magneticoptical switches are emphasized. [doi:10.1295/polymj.PJ2007006] KEY WORDS Dendrimer / Light Harvesting / Photoinduced Energy Transfer / Photoinduced Electron Transfer / Magnetic Soft Materials / Spin Transition / Radicals / Dendritic architecture, characterized by its iteratively branched structure, is one of the most pervasive topology, which can be easily found at a variety of dimensional scales such as in abiotic phenomena including snow crystals and lightning patterns, and in biological systems, for example, tree branches and neuron networks. From a synthetic point of view, such architecture will enable chemists to construct molecules with their components linked in a radial fashion, which is hardly achieved via ordinary synthetic methodology. With the development of two main strategies, i.e. divergent and convergent approaches, 1-3 innumerable dendritic structures have been reported up to date. 'Dendrimer' termed by Tomalia in 1985 has been recognized as the fourth major class of macromolecular architectures. Benefiting from the well-established synthetic strategies, chemists are now able to precisely control the size and shape of the dendrimer frameworks as well as the numbers and positions of the functional groups. This molecular design flexibility is one of the most unique characters, which distinguished dendrimers from all other linear, hyperbranched, and star-shaped macromolecules.On the other hand, the myriad of sophisticated natural processes such as light harvesting, energy transduction and conversion stimulated chemists in the design of various functional molecules and their assemblies, which lead to many significant scientific and technological advances over the past decades. In relation to this, dendritic architecture, due to its well-def...

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A Dendrimer-Based Electron Antenna: Paired Electron-Transfer Reactions in Dendrimers with a 4,4‘-Bipyridine Core and Naphthalene Peripheral Groups

Cited by 87 publications

References 35 publications

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

Photoinduced Charge Accumulation in Molecular Systems

Dendritic Architectures for Design of Photo– and Spin–Functional Nanomaterials

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