Computational Study of the Lowest Triplet State of Ruthenium Polypyridyl Complexes Used in Artificial Photosynthesis

Borg, O. Anders; Godinho, S. S. M. C.; Lundqvist, Maria; Lunell, Sten; Persson, Petter

doi:10.1021/jp8000702

Cited by 60 publications

(104 citation statements)

References 54 publications

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“…Moreover, TD-DFT has been shown to describe the MLCT states of large ruthenium complexes correctly, by comparison of the computed absorption spectra with experimental ones and in some cases with accurate multiconfigurational calculations such as CASSCF/CASPT2. 14,15 In addition to our previous work, Borg et al 16 also recently computed MLCT states of similar complexes with B3LYP. Thus, we think that in our case there is no reason for concern and that TDDFT should be reliable.…”

Section: Introductionmentioning

confidence: 64%

Spin-orbit effects on the photophysical properties of Ru(bpy)32+

Heully¹,

Alary²,

Boggio‐Pasqua³

2009

The Journal of Chemical Physics

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We present in this article a detailed study of the photophysics of the Ru(bpy)(3)(2+) complex based on a formalism using density functional theory and an a posteriori treatment of the spin-orbit coupling. The absorption and emission spectra were computed and a very good agreement was obtained with the available experimental data. This work also reveals for the first time that the triplet metal-centered (MC) dd state cannot deactivate radiatively and corresponds to a transient structure for the nonradiative de-excitation of the triplet metal-to-ligand charge transfer (MLCT) state. Thus, a competition takes place between the luminescence of the MLCT state and nonradiative decay back to the ground state via population of the MC state. This radiationless return to the ground state occurs via a deactivation funnel which has been characterized for the first time by optimizing the minimum energy crossing point between the triplet MC and singlet ground state potential energy surfaces. Its low-lying energy position relative to the energy necessary to access the MC minimum suggests that this funnel will be readily accessible.

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Section: Introductionmentioning

confidence: 64%

Spin-orbit effects on the photophysical properties of Ru(bpy)32+

Heully¹,

Alary²,

Boggio‐Pasqua³

2009

The Journal of Chemical Physics

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“…60 Computationally, it is frequently the case that ΔSCF cycles find an optimized geometry for a 3 MC, and it is both challenging and computationally expensive to identify the energy of the 3 MLCT. Difficult cases were dealt with by using Kohn-Sham orbitals determined from time dependent DFT calculations as a starting point for SCF optimization.…”

Section: Scheme 2 Relevant Atom Labeling For [Ru(tpy) 2 ] 2þ (Top) Amentioning

confidence: 99%

Computational Exploration of Heterolytic Halogen−Carbon Bond Scission Photoreactions in Ruthenium Polypyridyl Complexes

Vallett

Damrauer

2011

J. Phys. Chem. A

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Energy wasting charge recombination is an efficiency limiting process in efforts to achieve solar energy storage. Here, density functional theory is used to explore the thermodynamics of photochemical energy storage reactions in several ruthenium polypyridyl complexes where heterolytic halogen-carbon bond scission occurs after light-induced formation of the triplet metal to ligand charge transfer ((3)MLCT) state, as seen in the following reaction: [Ru(II)(A)(n)(L-X)](2+) + hν → [Ru(III)(A)(n)(L-X)(•-)](2+)* → [Ru(III)(A)(n)(L·)](3+) + X(-) (L = polypyridine ligand; X = Cl, Br, and I; A = ancillary ligand). A thermochemical cycle is employed to determine structural and electronic factors influencing ΔE(rxn). Significant energetic penalties in the oxidation of the metal center are mitigated through methylation of ancillary ligands or introduction of amine ancillary ligands. Methylation of the halogenated ligand maintains energy stored in the (3)MLCT state. Reduction in ΔE(rxn) is obtained by exploiting strain in the coordination geometry or in sterically encumbered ligands that is released upon bond breaking. Formation of a contact ion pair is significantly more favorable than complete separation of charged products, and shows negative ΔE with respect to the (3)MLCT state in certain cases. Future tunability in stored energy may be achieved through careful manipulation of ligand structure and charge on ancillary ligands.

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“…On the other side, theoretical inorganic photochemistry has significantly matured in the past 10 years. Density functional based methods have particularly enabled computational photochemists to approach photophysical events taking place in Ru(II) polypyridine complexes, such as ground state geometries and Franck-Condon excited state distribution [6] , [7] , [8] , [9] , [10] , [11], 3 MLCT (metal-to-ligand charge transfer) [12] , [13] , [14] , [15] , [16] and 3 MC (metal centred) [17] , [18] , [19] excited state relaxation, triplet-triplet internal conversion [20] , [21] , [22], luminescence [12] , [16] , [17] , [23] , [24] or non radiative deactivation [25] , [26]. Some of these studies are meant to rationalize experimental observations or unravel complex mechanisms; others serve as predictive tool to anticipate the properties of yet unknown compounds.…”

Section: Introductionmentioning

confidence: 99%

DFT rationalization of the room-temperature luminescence properties of Ru(bpy) 3 2+ and Ru(tpy) 2 2+ : 3MLCT–3MC minimum energy path from NEB calculations and emission spectra from VRES calculations

et al. 2018

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Extensive experimental data covering 40 years of research are available on Ru(bpy) 3 2+ and Ru(tpy) 2 2+ , which are the archetypes of inorganic photochemistry. The last decade has enabled computational chemists to tackle this topic through density functional theory and to shed some new light on our old friends. For the first time, this theoretical study maps the minimum energy path linking the 3 MLCT (metal-to-ligand charge transfer) and the 3 MC (metal centred) states with the nudged elastic band (NEB) method, also providing the calculation of the corresponding energy barrier. Remarkably, the obtained data are in very good agreement with the experimental activation energies reported from variable temperature luminescence measurements. Calculation of vibrationally resolved electronic spectra (VRES) is also in excellent agreement with the experimental emission maximum and bandshape of Ru(bpy) 3 2+. Additionally, the 3 MC-GS minimum energy crossing point (MECP) was optimized for each complex. The combination of these data rationalizes the room-temperature luminescence of the bpy complex and non-luminescence of the tpy complex.

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Computational Study of the Lowest Triplet State of Ruthenium Polypyridyl Complexes Used in Artificial Photosynthesis

Cited by 60 publications

References 54 publications

Spin-orbit effects on the photophysical properties of Ru(bpy)32+

Spin-orbit effects on the photophysical properties of Ru(bpy)32+

Computational Exploration of Heterolytic Halogen−Carbon Bond Scission Photoreactions in Ruthenium Polypyridyl Complexes

DFT rationalization of the room-temperature luminescence properties of Ru(bpy) 3 2+ and Ru(tpy) 2 2+ : 3MLCT–3MC minimum energy path from NEB calculations and emission spectra from VRES calculations

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