Excited state properties of a series of molecular photocatalysts investigated by time dependent density functional theory

Martynow, Miłosz; Kupfer, Stephan; Rau, Sven; Guthmuller, Julien

doi:10.1039/c9cp00335e

Cited by 16 publications

(29 citation statements)

References 35 publications

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“…Moreover, TD-DFT supports the absence of bridge-centered ππ* states which are typically found for structurally related complexes like Rutpphz. [64][65][66] This hints towards a higher contribution of the phen moiety on the formation of the excited states in Rudpymp compared to Rupqp and agrees with the rR spectroscopic findings, revealing strong phen-type vibrational modes for Rudpymp, which are absent in the rR spectra of Rupqp.…”

Section: Characterization Of the Long-lived Excited Statessupporting

confidence: 86%

Pyrimidoquinxoalinophenanthroline opens next chapter in design of bridging ligands for artificial photosynthesis

Brückmann

Müller

Maisuradze

et al. 2021

Preprint

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Using a dehydrogenative chemistry on the complex approach, a new polypyridine bridging ligand that bridges the gap of already existing systems is synthesized. By the usage of versatile cross-coupling reactions two different coordination spheres are included in the ligand architecture. Due to the twisted geometry of the novel ditopic ligand, the resultant division of the ligand in two distinct subunits leads to steady state as well as excited state properties of the corresponding mononuclear Ru(II) polypyridine complex resembling those of prototype [Ru(bpy)3]2+ (bpy = 2,2´-bipyridine). The localization of the initially optically excited and the nature of the long-lived excited states on the Ru-facing ligand spheres is evaluated by resonance Raman and fs-TA spectroscopy, respectively, and supported by DFT and TDDFT calculations. Coordination of a second metal (Zn or Rh) to the available bis-pyrimidyl-like coordination sphere strongly influences the frontier molecular orbitals apparent by e.g., luminescence quenching. Thus, the new bridging ligand motif offers electronic properties which can be adjusted by the nature of the second metal center. Using the heterodinuclear Ru-Rh complex, visible light-driven reduction of NAD+ to NADH was achieved, highlighting the potential of this system for photocatalytic applications.

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Section: Characterization Of the Long-lived Excited Statessupporting

confidence: 86%

Pyrimidoquinxoalinophenanthroline opens next chapter in design of bridging ligands for artificial photosynthesis

Brückmann

Müller

Maisuradze

et al. 2021

Preprint

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“…Additionally, the geometries of several excited states involved in the light-driven ET dynamics were optimized with TD-DFT. This computational protocol was already successfully applied to simulate the UV–vis absorption and resonance Raman spectra, the spectro-electrochemistry properties, and the ET dynamics in structurally related transition metal complexes. ,− ,, In particular, it was shown to provide a balanced description of the ground and excited states properties for electronic states of different nature. The effects of the interaction with a solvent (i.e., acetonitrile, ε = 35.688, n = 1.344) were taken into account for the ground state and the excited states properties by the integral equation formalism of the polarizable continuum model (IEFPCM).…”

Section: Theoretical Methodsmentioning

confidence: 99%

Effect of the Catalytic Center on the Electron Transfer Dynamics in Hydrogen-Evolving Ruthenium-Based Photocatalysts Investigated by Theoretical Calculations

2019

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The light-induced relaxation pathways in the molecular photocatalyst [(tbbpy) 2 Ru(tpphz)PtCl 2 ] 2+ are investigated with time-dependent density functional theory calculations together with the Marcus theory of electron transfer (ET). The calculations show that metal (Ru) to ligand (tpphz) charge transfer (MLCT) triplet states are populated following an excitation in the longer wavelength range of the absorption spectrum, but that an ET toward the catalytic center (PtCl 2 ) from these states is thermodynamically unfavorable, implying that charge separation can only occur via higher energy states in this system. Moreover, low-lying Pt-centered states can be populated and the calculations predict that they can form an excited state equilibrium with MLCT states localized on the tpphz ligand. A comparison with previously reported results for the photocatalyst [(tbbpy) 2 Ru-(tpphz)PdCl 2 ] 2+ , based on a PdCl 2 catalytic center, is provided in order to decipher the effect of the catalytic center on their respective photochemistry (Staniszewska, M.; Kupfer,

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“…In the periodic cell, we include four repeat units of the polymer and replace the remaining C 7 H 15 alkyl chains by a methyl group to reduce the computational effort. Such a substitution is known to only slightly modify the electronic structure of the polymer [23] . Furthermore, we also included two PF

_{6}^{-}

anions in the periodic unit cell, as indicated in Figure 2b, in order to counter‐balance the charge (

+ 2

) of the ruthenium complex.…”

Section: Computational Detailsmentioning

confidence: 99%

Coupling of photoactive transition metal complexes to a functional polymer matrix**

Putra

Seidenath

Kupfer

et al. 2021

Chemistry A European J

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Conductive polymers represent a promising alternative to semiconducting oxide electrodes typically used in dye-sensitized cathodes as they more easily allow a tuning of the physicochemical properties. This can then also be very beneficial for using them in light-driven catalysis. In this computational study, we address the coupling of Ru-based photosensitizers to a polymer matrix by combining two different first-principles electronic structure approaches. We use a periodic density functional theory code to properly account for the delocalized nature of the electronic states in the polymer. These ground state investigations are complemented by time-dependent density functional theory simulations to assess the Franck-Condon photophysics of the present photoactive hybrid material based on a molecular model system. Our results are consistent with recent experimental observations and allow to elucidate the light-driven redox chemical processes -eventually leading to charge separation -in the present functional hybrid systems with potential application as photocathode materials.

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Excited state properties of a series of molecular photocatalysts investigated by time dependent density functional theory

Abstract: Excited state characters and energies of molecular photocatalysts are calculated by TDDFT to deduce trends for the electron transfer efficiencies.

Cited by 16 publications

References 35 publications

Pyrimidoquinxoalinophenanthroline opens next chapter in design of bridging ligands for artificial photosynthesis

Pyrimidoquinxoalinophenanthroline opens next chapter in design of bridging ligands for artificial photosynthesis

Effect of the Catalytic Center on the Electron Transfer Dynamics in Hydrogen-Evolving Ruthenium-Based Photocatalysts Investigated by Theoretical Calculations

Coupling of photoactive transition metal complexes to a functional polymer matrix**

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