Spectroscopic and electrochemical properties of the dimer tetrakis(2,2'-bipyridine)(.mu.-2,3-bis(2-pyridyl)pyrazine)diruthenium(II) and its monomeric analog

Braunstein, Carlos; Baker, A. D.; Strekas, Thomas C.; Gafney, Harry D.

doi:10.1021/ic00175a013

Cited by 175 publications

(126 citation statements)

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“…While many of the features observed and discussed above for the monomer appear at comparable wavenumbers for the dimer, there are certain notable differences, including the shift of ω 5 from its position at 1519 cm 1 in the monomer to 1559 cm 1 in the dimer, along with a shift of the strong band observed near 1266 cm 1 in the monomer to 1244 cm 1 in the dimer, both assignments being in agreement with conclusions drawn earlier by other workers. 48,49 While the dimer appears to possess only one band in the region near 1400 cm 1 with excitation into the low-energy MLCT band near 530 nm, it is noted that another relatively strong band is observed at 1420 cm 1 upon excitation in the near-UV Table 1 region at 356 nm (spectra not shown), i.e. as in the case of the monomer, two dpp modes occur in this region.…”

Section: Dimermentioning

confidence: 92%

“…51 The complexes Ru(bpy) 2 Cl 2 and Ru(d8bpy) 2 Cl 2 were prepared from RuCl 3 ÐH 2 O, bpy and d8bpy by literature methods. 52 [Ru(bpy) 2 (dpp)](PF 6 ) 2 , [Ru(d8bpy) 2 (dpp)](PF 6 ) 2 , [(bpy) 2 Ru(dpp)Ru(bpy) 2 ](PF 6 ) 4 and [(d8bpy) 2 Ru(dpp)Ru(d8 bpy) 2 ](PF 6 ) 4 were prepared from Ru(bpy) 2 Cl 2 , Ru(d8bpy) 2 Cl 2 and a stoichiometric amount of the dpp ligand, according to the method described by Braunstein et al 49 The sample was purified by repeated recrystallization from 1 : 1 water-ethanol solution and further purified on Sephadex CMC-25 ion-exchange resin as described by Denti et al 40 …”

Section: Preparation Of Compoundsmentioning

confidence: 99%

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Resonance Raman and time‐resolved resonance Raman spectra of the monomeric and dimeric complexes of ruthenium(II) with 2,3‐bis(2‐pyridyl)pyrazine (dpp)

Su¹,

Kincaid²

2003

J Raman Spectroscopy

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The electronic absorption, resonance Raman (RR) and time-resolved resonance Raman (TR 3 ) spectra of the monomeric and dimeric complexes of ruthenium(II) with 2,3-bis(2-pyridyl)pyrazine (dpp) were measured, i.e. Ru(bpy) 2 dpp 2+ and Ru(bpy) 2 dppRu(bpy) 2 4+ , where bpy is 2,2 -bipyridine. In addition, in order to facilitate definitive assignments of the observed RR spectral parameters, the corresponding selectively labeled complexes employing perdeuterated bpy (d8bpy) were also prepared and studied. It is shown that using judiciously chosen excitation lines to acquire the RR spectra permits selective enhancement of vibrational features associated with specific molecular fragments of the complexes, facilitating structural characterization of ground states of each complex. In addition, the TR 3 spectrum of the monomeric complex yields vibrational signatures of its 3 MLCT state, which is consistent with polarization of electron density towards the pyrazyl fragment; corresponding studies of the dimeric complex failed to provide conclusive evidence for modes attributable to an anion radical fragment, presumably owing to lack of effective enhancement with the excitation lines available.

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Section: Dimermentioning

confidence: 92%

Section: Preparation Of Compoundsmentioning

confidence: 99%

Resonance Raman and time‐resolved resonance Raman spectra of the monomeric and dimeric complexes of ruthenium(II) with 2,3‐bis(2‐pyridyl)pyrazine (dpp)

Su¹,

Kincaid²

2003

J Raman Spectroscopy

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“…Replacing one or more of the bpy of [Ru(bpy) 3 ] 2 þ with polyazine BLs allows these prototypical LAs to be incorporated into large molecular assemblies, such as photochemical molecular devices [29][30][31][32][33][37][38][39]. The most studied of such systems is [Ru(bpy) 2 (dpp)] 2 þ , Figure 19.4 [29][30][31].…”

Section: Polyazine Bridging Ligands To Construct Photochemical Molecumentioning

confidence: 99%

“…The most studied of such systems is [Ru(bpy) 2 (dpp)] 2 þ , Figure 19.4 [29][30][31]. The remote nitrogen atoms of the BL allows for the construction of polymetallic systems using this LA.…”

Section: Polyazine Bridging Ligands To Construct Photochemical Molecumentioning

confidence: 99%

“…dpp(p Ã ) MLCT state, at l abs max ¼ 475 nm, with the promoted electron formally located on the dpp used for attachment to additional metal centers. The 3 MLCT state is emissive (l em max ¼ 691 nm) with t ¼ 240 ns in RT aerated acetonitrile solution [29][30][31]. The redox chemistry shows a Ru II/III oxidation at 1.31 V versus SCE (saturated calomel electrode) with the dpp 0/À couple occurring at À1.06 V versus SCE, prior to the bpy 0/À couple.…”

Section: Polyazine Bridging Ligands To Construct Photochemical Molecumentioning

confidence: 99%

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Supramolecular Complexes as Photoinitiated Electron Collectors: Applications in Solar Hydrogen Production

Arachchige

Brewer

On Solar Hydrogen &Amp; Nanotechnology

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The urgent need to explore alternative energy sources has stimulated solar energy research globally. Solar energy that reaches the southern United States has an instantaneous maximum intensity of 1 kW m À2 and an average 24 h intensity of 250 W m À2 in a year [1]. It is a clean, abundant, and renewable energy source. Solar energy research is concentrated on its direct conversion to electricity in photovoltaic devices, conversion to heat in solar thermal devices, or conversion to chemical energy to produce fuels via artificial photosynthesis. Hydrogen has been proposed as an energy solution for the future due to its high energy content per gram (120 kJ g À1 ) and burning hydrogen results in only energy and water, having no impact on our carbon foot print. Solar Water SplittingSolar hydrogen production through water splitting is an attractive alternative energy solution for the future [1][2][3][4][5][6][7]. Solar water splitting uses light energy from the sun to convert water into hydrogen and oxygen. Water splitting is a challenging, energetically uphill process. The reactions involved in water splitting require bond breaking, bond formation and multielectron

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Hydrogen Production from Water: Photocatalysis

Arachchige

Brewer

2005

Encyclopedia of Inorganic Chemistry

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Photocatalytic hydrogen production from water provides an attractive but challenging approach to meeting our global energy needs. Design and development of systems that utilize visible light to drive the energetically favorable, multielectron reduction of water to produce hydrogen fuel have been of long‐term interest. Addressing the challenges of efficient harvesting of solar energy to produce transportable fuels requires ongoing, sustained research in this field. Current technologies utilize photobiological methods, photoelectrochemical methods, and molecular photocatalysis. This article focuses on the recent progress of proton or water reduction using supramolecular photocatalysts. These photochemical molecular devices often couple charge‐transfer light absorbers (LAs) to reactive metals in complex molecular architectures. Linking multiple components into large molecular assemblies allows for applications requiring complex functions. Early successes in supramolecular photocatalysts for solar hydrogen production are summarized. The redox, excited state properties, and photochemical properties of supramolecular systems applicable in photocatalytic hydrogen production are presented. Fundamental studies of the perturbations of subunit properties upon incorporation into supramolecular arrays are paramount to their successful application in this forum. Optical excitation typically affords a metal‐to‐ligand charge‐transfer state that is quenched by electron transfer, providing reduced complexes with reactive metals able to deliver the electrons to substrates. Sacrificial electron donors provide coupling to oxidative chemistry, allowing independent study of photocatalysts and hydrogen production schemes. Supramolecular chemistry allows modulation of redox, photophysical, and photochemical properties by component modification. Coupling multiple LAs to an electron acceptor, which, when reduced by multiple electrons, provides photoinitiated electron collectors (ECs). Photoinitiated ECs, which collect multiple electrons on a reactive rhodium center with the supramolecular architecture remaining, reduce water to hydrogen fuel. Mixed‐valence systems that promote HX reduction to produce hydrogen have also been described. Coupling of charge‐transfer LAs to cobalt, iron, palladium, or platinum is a topic of recent interest in the design of water reduction photocatalysts. The general design considerations for the development of supramolecular assemblies that function as photocatalysts for proton reduction are discussed, providing valuable insight into engineering efficient solar hydrogen production catalysts for water reduction. Mechanistic studies remain important to understanding this complex multielectron photochemistry, which will aid in future molecular design. Much remains to be mastered in this complicated, multielectron photochemistry but recently there is increased awareness and interest in this field.

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Spectroscopic and electrochemical properties of the dimer tetrakis(2,2'-bipyridine)(.mu.-2,3-bis(2-pyridyl)pyrazine)diruthenium(II) and its monomeric analog

Cited by 175 publications

References 0 publications

Resonance Raman and time‐resolved resonance Raman spectra of the monomeric and dimeric complexes of ruthenium(II) with 2,3‐bis(2‐pyridyl)pyrazine (dpp)

Resonance Raman and time‐resolved resonance Raman spectra of the monomeric and dimeric complexes of ruthenium(II) with 2,3‐bis(2‐pyridyl)pyrazine (dpp)

Supramolecular Complexes as Photoinitiated Electron Collectors: Applications in Solar Hydrogen Production

Hydrogen Production from Water: Photocatalysis

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