Polynuclear Polypyridine Complexes Incorporating Ru(II), Os(II), and Pt(II):  Decanuclear Dendrimeric Antennas

Sommovigo, Milena; Denti, Gianfranco; Serroni, Scolastica; Campagna, Sebastiano; Mingazzini, Claudio; Mariotti, Cristina; Juris, Alberto

doi:10.1021/ic001217x

Cited by 51 publications

(32 citation statements)

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“…Furthermore, the EET is directed only towards the Os core, in contrast to previously studied transition metal-polypyridine complexes, where the energy migrates not only to the center Os 3 MLCT state but also to the periphery of the molecule. [33][34][35][36][37] The unidirectional EET path makes the OsRu 3 pyr 6 transition-metal polypyridine dendrimer a good candidate for artificial light harvesting.…”

Section: Discussionmentioning

confidence: 99%

“…[40,41] Other studies on larger transition metal-polypyridine complexes, with an additional Ru layer (OsRu 3 Ru 6 ), have revealed two EET paths, namely, a path directed only towards the central Os metal atom and another one directed towards the peripheral Ru-centered ligands. [33][34][35][36][37] Hence, in OsRu 3 Ru 6 , the directional EET central for artificial photosynthetic antennas is unfortunately lost. A different approach for extending the OsRu 3 -core building block is therefore needed.…”

Section: A C H T U N G T R E N N U N G [(Dpp)rua C H T U N G T R E N mentioning

confidence: 99%

“…[33][34][35][36][37] The absorption cross-section and, consequently, the light-harvesting ability is in this way enhanced in the visible spectral region. However, as mentioned in the Introduction, the absorbed energy has been shown to migrate in two directions from the Ru [ [33][34][35][36][37] Directional EET, which is a key issue in finding antennas for artificial photosynthesis, is then lost. The transitionmetal complex studied herein presents an interesting solution to this problem.…”

Section: Improving the Light-harvesting Propertiesmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: A C H T U N G T R E N N U N G [(Dpp)rua C H T U N G T R E N mentioning

confidence: 99%

Section: Improving the Light-harvesting Propertiesmentioning

confidence: 99%

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Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

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“…Brewer and co-workers developed the active trinuclear Ru–Rh–Ru and tetranuclear Ru 2 –Ru–Pt complexes3236 comprising two and three photocentres, respectively, achieving 870 turnover number (TON) after 46 h. Sakai also accomplished higher H 2 production by preparing trinuclear Ru–Pt 2 and tetranuclear Ru–Pt 3 complexes introducing two and three reactive centres, respectively, in comparison with the dinuclear Ru–Pt analogue12. Moreover, a decanuclear OsRu 3 Pt 6 complex with dendrimeric chromophores was found to exhibit a remarkable antennae effect, where all the absorbed energy is efficiently transferred to a single Os unit37, although no test for multi-electron photocatalysis was performed. Nevertheless, simply increasing the metal nuclearity in a single PMD based on covalent multi-metallic complexes may lead to undirectional electron transfer and tedious separation of various geometric and optical isomers22.…”

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A metal-organic cage incorporating multiple light harvesting and catalytic centres for photochemical hydrogen production

Chen¹,

et al. 2016

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Photocatalytic water splitting is a natural but challenging chemical way of harnessing renewable solar power to generate clean hydrogen energy. Here we report a potential hydrogen-evolving photochemical molecular device based on a self-assembled ruthenium–palladium heterometallic coordination cage, incorporating multiple photo- and catalytic metal centres. The photophysical properties are investigated by absorption/emission spectroscopy, electrochemical measurements and preliminary DFT calculations and the stepwise electron transfer processes from ruthenium-photocentres to catalytic palladium-centres is probed by ultrafast transient absorption spectroscopy. The photocatalytic hydrogen production assessments reveal an initial reaction rate of 380 μmol h−1 and a turnover number of 635 after 48 h. The efficient hydrogen production may derive from the directional electron transfers through multiple channels owing to proper organization of the photo- and catalytic multi-units within the octahedral cage, which may open a new door to design photochemical molecular devices with well-organized metallosupramolecules for homogenous photocatalytic applications.

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“…Moreover, it should also be noted that several topologies, different from the most common tetranuclear, decanuclear and docosanuclear species, can be obtained by combining in different ways dendrimer “fragments”, called dendrons. The synthetic methods used allowed us also to prepare dendrimers containing at the same time three different metals (Os, Ru, and Pt) …”

Section: Synthetic Strategy For Photo‐and Redox‐active Ruii Dendrimentioning

confidence: 99%

Photo‐ and Redox‐Active Metal Dendrimers: A Journey from Molecular Design to Applications and Self‐Aggregated Systems

et al. 2018

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The scientific adventure starting from simple dinuclear ruthenium(II) complexes and leading to the design, preparation, and study of photo-and redox-active polynuclear metal dendrimers capable of performing useful photo-driven processes is reviewed through decades of activity. The recent appli- [a] 3887 cations of luminescent metal dendrimers in the field of artificial photosynthesis -in particular as far as the photochemical water oxidation process is concerned -and their very recently revealed self-aggregating properties, including concentrationdependent photoinduced energy transfer, are also shown. the investigation of intercomponent photoinduced energy and electron-transfer processes. The simultaneous growth of supramolecular photochemistry [11] was indeed significantly powered by such studies, and an evolution towards larger multicomponent assembled systems appeared almost obvious. Scheme 1. Structural formulas of the polypyridine ligands mainly used for the synthesis of the metal dendrimers here described and their representations, used in the following figures.Within such a scenario, our research group started a collaboration with the groups of Vincenzo Balzani in Bologna and of Gianfranco Denti in Pisa, with the aim of building up unprecedented methods toward the synthesis of metal complexes of high nuclearity, having in mind some guidelines for preparing supramolecular assemblies capable of exhibiting made-to-order properties. In particular, photoinduced intramolecular energy transfer and predetermined redox patterns were among the properties we were looking for, since such properties were essential to open the way to artificial antenna systems for light harvesting purposes and for multiple charge storage. After the initial studies, that led us to synthesize and investigate the lumi-Microreview nescence properties and redox behavior of -among othersdinuclear, trinuclear, tetranuclear, hexanuclear, heptanuclear, Sebastiano Campagna received his Laurea in Chemistry from the University of Messina in 1983. Since 1985 to 1997 he worked in the Photochemistry group led by Vincenzo Balzani at the University of Bologna. In 1998 he joined the Faculty of Science of the University of Messina, where he became full professor in 2002. His research interests include photochemistry and photophysics of coordination compounds and supramolecular species, photoinduced electron and energy transfer, and artificial photosynthesis. Giuseppina La Ganga is post-doc student at University of Messina. She received her master degree in 2009 and received her PhD in Chemistry in 2014 from the University of Messina, working in the group of Prof. Sebastiano Campagna on supramolecular photochemistry. Her scientific interest is focused on renewable energies, with particular emphasis on the generation of solar fuels. She has developed and studied in detail various kinds of sensitizer-antenna dyes and multi-electron catalysts for water oxidation. Ambra Cancelliere obtained her Master degree in Chemistry in 2016 from the University of Messina...

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Polynuclear Polypyridine Complexes Incorporating Ru(II), Os(II), and Pt(II): Decanuclear Dendrimeric Antennas

Cited by 51 publications

References 38 publications

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

Extending the Light‐Harvesting Properties of Transition‐Metal Dendrimers

A metal-organic cage incorporating multiple light harvesting and catalytic centres for photochemical hydrogen production

Photo‐ and Redox‐Active Metal Dendrimers: A Journey from Molecular Design to Applications and Self‐Aggregated Systems

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