Photoinduced Mixed Valency in  Zinc Porphyrin Dimer of Triruthenium Cluster Dyads

Henderson, Jane; Kubiak, Clifford P.

doi:10.1021/ic501889u

Cited by 16 publications

(32 citation statements)

References 57 publications

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“…49 Notably, this is one of the very few examples in the literature, where a PIIVCT signal is reported. [31][32][33][34][35][36][37][38][39][40] Our PIIVCT assignment of the NIR photoinduced transition in 3 MLCTz spectrum was independently supported by theoretical calculations. DFT methods were employed to identify the lowest triplet excited state of [RuRu] 2+ and its electronic configuration and (TD)DFT calculations were performed to simulate its electronic spectra.…”

Section: Resultssupporting

confidence: 54%

“…A similar reasoning has been used in conjunction with the shifted photoinduced LMCT markers, in comparison with GS LMCT absorptions, in, for example, {Ru(NCS)} complexes . Notably, this is one of the very few examples in the literature, where a PIIVCT signal is reported. − …”

Section: Results and Discussionmentioning

confidence: 91%

“…[22][23][24][25][26][27][28] The position, intensity, and shape of their intervalence charge transfer (IVCT) transitions enables insights into those physicochemical parameters that relate to the electron 2 transfer processes between the two metal centers. 29,30 Reports of excited-state mixed-valence species are rather scarce, [31][32][33][34][35][36][37][38][39][40] probably due the experimental challenge of detecting them. If both centers are sufficiently coupled, the resulting photoinduced mixed-valence (PIMV) state should give rise to a very distinctive strong photoinduced intervalence charge transfer (PIIVCT) absorption band in the NIR region, and hence should be detectable thanks to advances in detection systems and pump-probe setups.…”

Section: Introductionmentioning

confidence: 99%

“…There is an extensive literature of mixed-valence complexes in the ground state, especially for systems with a (dπ M ) 5 (dπ M’ ) 6 electronic configuration. These are simple models for studies on metal–metal electronic communication, which is of great relevance in the context of energy conversion. − The position, intensity, and shape of their intervalence charge transfer (IVCT) transitions enable insights into those physicochemical parameters that relate to the electron transfer processes between the two metal centers. , Reports of excited-state mixed-valence species are rather scarce, − probably due to the experimental challenge of detecting them. If both centers are sufficiently coupled, the resulting photoinduced mixed-valence (PIMV) state should give rise to a very distinctive strong photoinduced intervalence charge transfer (PIIVCT) absorption band in the NIR region, and hence, they should be detectable thanks to advances in detection systems and pump–probe setups.…”

Section: Introductionmentioning

confidence: 99%

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Coexistence of MLCT Excited States of Different Symmetry upon Photoexcitation of a Single Molecular Species

et al. 2019

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Photoexcitationof [Ru(tpy)(bpy)(-CN)Ru(py) 4 Cl] 2+ ([RuRu] 2+ ) at 387 nm results in the population of two 3 MLCT excited states of different symmetry that coexist in the nanosecond scale. Common to both states is an excited electron in a tpy-based orbital. Their configuration differs in the position of the hole. In one excited state, 3 MLCTz, the hole sits in an orbital parallel to the intermetallic axis allowing for a strong metal-metal electronic interaction. As a result, 3 MLCTz is highly delocalized over both metal centres and shows an intense photoinduced intervalence charge transfer (PIIVCT) NIR signature. In the other excited state, 3 MLCTxy, the hole is localized in an orbital perpendicular to the intermetallic axis and hence, significant intermetallic coupling is absent. This state shows no PIIVCT in the NIR and its spectrum is very similar to the one observed for the monometallic [Ru(tpy)(bpy)(CN)] + reference. Both 3 MLCT excited states have nanosecond lifetimes. The intervening energy barrier for a hole reconfiguration between the two different 3 MLCT excited states offers the opportunity to exploit wavefunctions of different symmetry before either the interconversion between them or the decay to the ground state is operative.

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Section: Resultssupporting

confidence: 54%

Section: Results and Discussionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coexistence of MLCT Excited States of Different Symmetry upon Photoexcitation of a Single Molecular Species

et al. 2019

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“…To the best of our knowledge these are the only five transition metal clusters with the (CH 2 O 2 ) 2– moiety were structurally characterized, and other metal ion complexes with this rare bridging ligand are not known yet, particularly the more amenable Fe(III) congener, ruthenium ions. A great deal of focus has been paid for the past two decades to link the oxo-centered ruthenium triangles using various bridging ligands to better understand the mechanism of electron transfer and fine-tune the electron transfer rate between the two triangles …”

Section: Introductionmentioning

confidence: 99%

Unusual Methylenediolate Bridged Hexanuclear Ruthenium(III) Complexes: Syntheses and Their Application

et al. 2018

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Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general molecular formula of [Ru6 III(O)2(μ4-η2-η2-CH2O2)(t-BuCO2)12(L)2] where L = pyridine (1) or 4-dimethylamino pyridine (DMAP; 2) or 4-cyanopyridine (3). Complexes 1 and 3 were solved in the tetragonal I4̅c2 and P4 1212 space group, respectively, while 2 crystallized in the monoclinic system with P2 1 /c space group. In all three complexes, two oxo-centered Ru(III) triangles were bridged by a unique and a rare methylenediolate (CH2O2)2–) ligand. This (CH2O2)2– group is reported to be an intermediate, which is not isolated in its metal-free form, to date, as it is unstable. Control experiments performed evidently reveal that the unique reaction condition followed is mandatory to isolate 1–3 and the origin of (CH2O2)2– is unknown at the moment, as no precursor was used to form this intermediate. The presence of (CH2O2)2– identified through X-ray diffraction was further unambiguously confirmed by various 1D (1H and 13C) and 2D-NMR (HSQC, TOCSY, NOESY, and DEPT) spectroscopies. Direct current (dc) magnetic susceptibility measurements performed on 1 and 2 reveal the predominant antiferromagnetic exchange interaction between the Ru(III) centers result in a diamagnetic ground state at 2.0 K. The paramagnetic influence of 1–3 at room temperature evidently felt by the 1H nuclei of the (CH2O2)2– unit predominates compared to other NMR active nuclei in the complexes. The presence of an electron donating or withdrawing substituent on the terminal pyridine results in significant change in the dihedral angle of two oxo-centered triangular (Ru3O−) planes. The change in the structural parameters of 1–3 due to the substituents markedly reflected on the absorption profile and redox behavior, which are systematically investigated. Preliminary galvanostatic charge/discharge cycling experiments performed on a representative complex (3) suggest that 3 can be a promising candidate to employ as an effective multiple electron charge carrier in a nonaqueous redox flow battery.

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An Introduction to the Chemistry and Properties of Excited‐State Mixed‐Valence Systems

Ramírez‐Wierzbicki,

Cotic,

Cadranel

2024

Encyclopedia of Inorganic and Bioinorganic Chemistry

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While ground‐state mixed‐valence systems are very well known, excited‐state mixed‐valence (ES‐MV) systems received comparably less attention. Intervalence charge‐transfer (IVCT) excited states, locally excited mixed‐valence (LE‐MV) systems, and photoinduced mixed‐valence (PI‐MV) systems are different types of ES‐MV systems. They are the simplest models for excited‐state electron transfer reactions, and therefore crucial in the development of solar energy conversion schemes. IVCT exited states are the best‐known ES‐MV systems and are usually called electronic isomers or redox isomers of the ground state. Their back electron transfer reactivity depends on whether it proceeds with or without spin conservation. LE‐MV systems feature locally excited donors or acceptors, and their reactivity might be dominated by locally excited states or IVCT excited states. PI‐MV systems include charge transfer counterparts, which can adopt different spatial distributions with respect to the mixed‐valence core. Depending on the location of the charge‐transfer counterpart, drastic changes in the electronic configuration of PI‐MV systems can arise, with equally important impact on their reactivity in comparison to only the donor or the acceptor. This review addresses different processes that lead to the generation of ES‐MV systems, their properties, reactivity, and spectroscopy. Additionally, the experimental techniques usually employed to study ES‐MV systems are briefly discussed, together with theoretical formalisms and classifications which were developed for the ground state but can also be applied to the excited state.

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Photoinduced Mixed Valency in Zinc Porphyrin Dimer of Triruthenium Cluster Dyads

Cited by 16 publications

References 57 publications

Coexistence of MLCT Excited States of Different Symmetry upon Photoexcitation of a Single Molecular Species

Coexistence of MLCT Excited States of Different Symmetry upon Photoexcitation of a Single Molecular Species

Unusual Methylenediolate Bridged Hexanuclear Ruthenium(III) Complexes: Syntheses and Their Application

An Introduction to the Chemistry and Properties of Excited‐State Mixed‐Valence Systems

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