Analysis of Electronic Transitions as the Difference of Electron Attachment and Detachment Densities

Head‐Gordon, Martin; Graña, Ana M.; Maurice, David; White, Christopher A.

doi:10.1021/j100039a012

Cited by 322 publications

(365 citation statements)

References 6 publications

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“…Calculations were carried out using the Gaussian 09 package. 34 Detachment-attachment densities 35 were calculated using the Q-Chem 3.0 package. 36 …”

Section: Calculationsmentioning

confidence: 99%

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Oum

Lohse

Klein

et al. 2013

Phys. Chem. Chem. Phys.

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The relaxation dynamics of the dye D35 has been characterized by transient absorption spectroscopy in acetonitrile and on TiO 2 and ZrO 2 thin films. In acetonitrile, upon photoexcitation of the dye via the S 0 -S 1 transition, we observed ultrafast solvation dynamics with subpicosecond time constants.Subsequent decay of the S 1 excited state absorption (ESA) band with a 7.1 ps time constant is tentatively assigned to structural relaxation in the excited state, and a spectral decay with 203 ps time constant results from internal conversion (IC) back to S 0 . On TiO 2 , we observed fast (o90 fs) electron injection from the S 1 state of D35 into the TiO 2 conduction band, followed by a biphasic dynamics arising from changes in a transient Stark field at the interface, with time constants of 0.8 and 12 ps, resulting in a characteristic blue-shift of the S 0 -S 1 absorption band. Several processes can contribute to this spectral shift: (i) photoexcitation induces immediate formation of D35 + radical cations, which initially form electron-cation complexes; (ii) dissociation of these complexes generates mobile electrons, and when they start diffusing in the mesoporous TiO 2 , the local electrostatic field may change; (iii) this may trigger the reorientation of D35 molecules in the changing electric field. A slower spectral decay on a nanosecond timescale is interpreted as a reduction of the local Stark field, as mobile electrons move deeper into TiO 2 and are progressively screened. Multiexponential electron-cation recombination occurs on much longer timescales, with time constants of 30 ms, 170 ms and 1.4 ms. For D35 adsorbed on ZrO 2 , there is no clear evidence for a transient Stark shift, which suggests that initially formed cation-electron (trap state) complexes do not dissociate to form mobile conduction band electrons.Multiexponential decay with time constants of 4, 35, and 550 ps is assigned to recombination between cations and trapped electrons, and also to a fraction of D35 molecules in S 1 which decay by IC to S 0 .Differential steady-state absorption spectra of D35 + in acetonitrile and dichloromethane provide access to the complete D 0 -D 1 band. The absorption spectra of D35 and D35 + are well described by TDDFT calculations employing the MPW1K functional.

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“…Calculations were carried out using the Gaussian 09 package. 34 Detachment-attachment densities 35 were calculated using the Q-Chem 3.0 package. 36 …”

Section: Calculationsmentioning

confidence: 99%

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Oum

Lohse

Klein

et al. 2013

Phys. Chem. Chem. Phys.

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“…Thirty-two singlet excited states with the corresponding oscillator strengths were determined with a Time-dependent Density Functional Theory (TD-DFT) [32,33] calculation. The electronic distribution and the localization of the singlet excited states were visualized using the electron density difference maps (EDDMs) [34][35][36]. GaussSum 1.05 was used for EDDMs calculations and GaussSum 2.2 for the electronic spectrum simulation (ν fwhm = 4000 cm −1 ) [37].…”

Section: Computational Detailsmentioning

confidence: 99%

Photoactivation of trans diamine platinum complexes in aqueous solution and effect on reactivity towards nucleotides

Cubo

Pizarro

Quiroga

et al. 2010

Journal of Inorganic Biochemistry

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We show that UVA irradiation (365 nm) of the Pt IV complex trans,trans,trans-[Pt IV Cl 2 (OH) 2 (dimethylamine)(isopropylamine)], 1, induces reduction to Pt II photoproducts. For the mixed amine Pt II complex, trans-[Pt II Cl 2 (isopropylamine)(methylamine)] (2), irradiation at 365 nm increases the rate and extent of hydrolysis, triggering the formation of diaqua species. Additionally, irradiation increases the extent of reaction of complex 2 with guanosine-5′-monophosphate (GMP) and affords mainly the bis-adduct, while reactions with adenosine-5′-monophosphate (AMP) and cytidine-5′-monophosphate (CMP) give rise only to mono-nucleotide adducts. Density Functional Theory calculations have been used to obtain insights into the electronic structure of complexes 1 and 2, and their photophysical and photochemical properties. UVA-irradiation can contribute to enhanced cytotoxic effects of diamine platinum drugs with trans geometry.

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“…This scheme uses the so-called excitation density, which can be viewed as a sum of the attachment and detachment electron densities. 49 The FED scheme, which is based on the fragment charge difference (FCD) method for electron transfer coupling, 13 holds exactly in the case of the configuration interaction of singly excited states (CIS) scheme, where there are no configurations including two-electron and higher excitations. For other methods including these excitations, in particular multi-reference ones, it should give a reasonable estimate if the electronic excitation can be well described by a one-electron transition.…”

Section: Introductionmentioning

confidence: 99%

Exciton delocalization, charge transfer, and electronic coupling for singlet excitation energy transfer between stacked nucleobases in DNA: An MS-CASPT2 study

Blancafort

Voityuk

2014

The Journal of Chemical Physics

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Articles you may be interested inFragment transition density method to calculate electronic coupling for excitation energy transfer J. Chem. Phys. 140, 244117 (2014) Exciton delocalization and singlet excitation energy transfer have been systematically studied for the complete set of 16 DNA nucleobase dimers in their ideal, single-strand stacked B-DNA conformation, at the MS-CASPT2 level of theory. The extent of exciton delocalization in the two lowest (π ,π * ) states of the dimers is determined using the symmetrized one-electron transition density matrices between the ground and excited states, and the electronic coupling is calculated using the delocalization measure and the energy splitting between the states [see F. Plasser, A. J. A. Aquino, W. L. Hase, and H. Lischka, J. Phys. Chem. A 116, 11151-11160 (2012)]. The calculated couplings lie between 0.05 eV and 0.14 eV. In the B-DNA conformation, where the interchromophoric distance is 3.38 Å, our couplings deviate significantly from those calculated with the transition charges, showing the importance of orbital overlap components for the couplings in this conformation. The calculation of the couplings is based on a two-state model for exciton delocalization. However, in three stacks with a purine in the 5 position and a pyrimidine in the 3 one (AT, GC, and GT), there is an energetically favored charge transfer state that mixes with the two lowest excited states. In these dimers we have applied a three-state model that considers the two locally excited diabatic states and the charge transfer state. Using the delocalization and charge transfer descriptors, we obtain all couplings between these three states. Our results are important in the context of DNA photophysics, since the calculated couplings can be used to parametrize effective Hamiltonians to model extended DNA stacks. Our calculations also suggest that the 5 -purine-pyrimidine-3 sequence favors the formation of charge transfer excited states.

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Analysis of Electronic Transitions as the Difference of Electron Attachment and Detachment Densities

Cited by 322 publications

References 6 publications

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Photoinduced ultrafast dynamics of the triphenylamine-based organic sensitizer D35 on TiO2, ZrO2 and in acetonitrile

Photoactivation of trans diamine platinum complexes in aqueous solution and effect on reactivity towards nucleotides

Exciton delocalization, charge transfer, and electronic coupling for singlet excitation energy transfer between stacked nucleobases in DNA: An MS-CASPT2 study

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