Charge transfer between two ferrocene groups linked by oligothiophene

Sato, Masaaki; Fukui, Kazuhiko; Sakamoto, Maki; Kashiwagi, Shin-ichiro; Hiroi, Masao

doi:10.1016/s0040-6090(01)01071-9

Cited by 23 publications

(15 citation statements)

References 14 publications

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“…The group of Sato has synthesized related ter-, quarter-, quinque-, and sexithiophenes (substituted in position 3 with hexyl or methoxy groups to increase the solubility) with terminal ferrocenyl moieties to create model systems for molecular wires, but these complexes also exhibited little or no separation of the ferrocene-based redox processes. 20,21 It seems likely that the larger redox splitting in the ferrocenyl-functionalized pyrroles 4, 9 and 16 is caused by the smaller energy gap between the ferrocenyl moieties and the heterocyclic bridging moiety as well as the larger delocalization of the pyrrole unit itself. 23 Therefore, the oligopyrroles may provide a more effective conduit for intermetallic charge transfer between the ferrocene units through the π-conjugated backbone.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

et al. 2013

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A series of (oligo)pyrroles featuring redox-active terminal ferrocenyl groups (Fc 2 -( c C 4 H 2 NPh) n (4, n = 1; 9, n = 2; 16, n = 3; 20, n = 4)) has been prepared using a Negishi C,C cross-coupling reaction protocol. The bi-, ter-and quarterpyrrole wire moieties have been built up by C,C cross-coupling reactions of trimethyl silyl protected pyrrole units in the presence of [Pd(CH 2 C(CH 3 ) 2 P( t C 4 H 9 ) 2 )(µ-Cl)] 2 as precatalyst. The structural properties of the title compounds were investigated by spectroscopic means and single-crystal X-ray diffraction studies (9, 16 and 20). The influence of the increasing number of N-phenyl pyrrole units on the electronic interaction between the iron centres was studied using electrochemistry (cyclic (CV) and square wave voltammetry (SWV)) as well as spectroelectrochemistry (in situ UV-Vis/NIR spectroscopy). With exception of the diferrocenyl quarterpyrrol 20, the application of [N n Bu 4 ][B(C 6 F 5 ) 4 ] as electrolyte allows the discrete oxidation of the ferrocenyl termini (∆E° ′ = 450 mV (4), ∆E° ′ = 320 mV (9), ∆E° ′ = 165 mV (16)) in cyclic and square wave voltammograms. However, the iron centres of 20 were oxidized simultaneously, generating dicationic 20 2+ . Additionally, one (9) or two (16 and 20) pyrrole-related well-defined reversible one-electron redox processes were observed. The cyclic voltammetry data reveal that the splitting of the ferrocene-based redox couples, ∆E° ′, decreases with increasing oligo-pyrrole chain length and hence, the larger metalmetal distance. The trends in ∆E° ′ with oligo-pyrrole structure also map to the electronic coupling between the ferrocene moieties as estimated by spectroelectrochemical UV-Vis/NIR measurements.Despite no direct metal-metal interaction in diferrocenyl quarterpyrrole 20, a large absorption in the NIR region is observed arising from photo-induced charge transfer from the oligopyrrole backbone to the redox-active ferrocenyl termini. These charge transfer absorptions have also been found in the dicationic oxidation state of the mono-(4), bi-(9) and terpyrroles (16). Within this series of diferrocenyl(oligo)pyrroles this CT band is shifted bathochromically with increasing chain length of the backbone motif.

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Section: Synthesis and Characterizationmentioning

confidence: 99%

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

et al. 2013

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“…Several molecules with Fc-oligothiophene chains were synthesized, with Fc complex at one end of the chain 53ab or at both ends 53cde, as models for a molecular wire [407,408]. The distribution of the electronic density after their electrochemical oxidation was studied.…”

Section: Compose Fc-thiophene Chainsmentioning

confidence: 99%

Metallocene-containing conjugated polymers

Vorotyntsev

Vasilyeva

2008

Advances in Colloid and Interface Science

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“…24,25 Sato et al previously also reported mixed valence systems containing biferrocenyl-capped oligothiophenes, but without quantitative discussion on charge delocalization in such systems. 26,27 Despite the extensive work in the field, systematic studies on the influence of oligothiophenes of various chain lengths on the electronic delocalization in bimetallic mixed valence complexes [ML n (bridge)ML n ] + are still scarce.…”

Section: ■ Introductionmentioning

confidence: 99%

Delocalization-to-Localization Charge Transition in Divinylthiophene-Bridged Biruthenium Complexes as a Function of Length of the Bridging Chain by Both IR Spectroscopy and Theoretical Investigations

Qian

et al. 2019

J. Phys. Chem. C

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A series of biruthenium complexes linked by oligothiophene bridges of variable lengths (4a–4d) have been prepared to probe intramolecular electronic delocalization as a function of the chain length of the bridging ligand. In going from monothiophene to quaterthiophene-bridged biruthenium-vinyl complex radical cations (4a +–4d +), the transition from a positive charge delocalized state to a localized state is clearly displayed by IR spectroscopy and density functional theory calculations and the bridge contributing to the charge and the unpaired spin density exhibits good linear correlation with the length of the bridging chain. The shortest member 4a + displays a charge delocalized mixed-valence property as a result of the strong electronic coupling between two ruthenium termini. In the longest member 4d + , the charge is nearly fully localized at the bridge and the mixed-valence property disappears. Therefore, for even longer systems, the charge should be exclusively localized on the bridge.

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Charge transfer between two ferrocene groups linked by oligothiophene

Cited by 23 publications

References 14 publications

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Metallocene-containing conjugated polymers

Delocalization-to-Localization Charge Transition in Divinylthiophene-Bridged Biruthenium Complexes as a Function of Length of the Bridging Chain by Both IR Spectroscopy and Theoretical Investigations

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