Long-range corrected DFT calculations of charge-transfer integrals in model metal-free phthalocyanine complexes

The excited states of perylene-based dye aggregates were investigated with emphasis on the description of the potential energy surfaces for the intermolecular motion in a dimer, which are of importance for exciton trapping. The aim is to investigate the applicability of TDDFT and semiempirical methods. The longitudinal displacement of two p-stacked molecules against each other is used as model and the methods are benchmarked against SCS-CC2 and SCS-ADC(2). Furthermore a simple character analysis is applied. In the case of the perylene dimer, CAM-B3LYP and xB97XD provide accurate results. However, while CAM-B3LYP fails for the PBI (perylene bisimide) dimer the performance of xB97XD is highly dependent on the used monomer geometry due to close-lying diabatic states. A change in geometry changes the character of the excited states even qualitatively. The accuracy of several other long-range corrected functionals (LC-BLYP, LC-xPBE, xB97X) and the effect of empirically tuning the range-separation parameter of xB97XD are also presented for this interesting case. Furthermore, it is shown that the semiempirical method OM2 fails to provide a correct description of the excited states when the orbital overlap plays a significant role. This is attributed to the too contracted basis set.

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“…LC‐BLYP and LC‐ ω PBE are typical examples, which are also used here. LC‐BLYP as implemented in Gaussian uses a range separation parameter

ω = 0.47 {bohr}^{- 1}

, while LC‐ ω PBE uses

ω = 0.4 {bohr}^{- 1}

.…”

Section: Resultsmentioning

confidence: 99%

“…Gaussian uses a range separation parameter x50:47 bohr 21 , [55,56] while LC-xPBE [42] uses x50:4 bohr 21 .…”

Section: Tddftmentioning

confidence: 99%

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

Walter

Krämer

Engels

2016

Int J of Quantum Chemistry

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“…The choice of the CAM-B3LYP functional stems from the improvement it allows in the treatment of charge-transfer states, as compared to conventional functionals. 62,63 Let us consider the case of the cis ligand arrangement first. As expected in case of correct structural assignment, the larger basis allowed for the calculation of a spectrum closer to the experimental spectra recorded for 5 (see below and Figure S28, SI).…”

Section: Resultsmentioning

confidence: 99%

Access to a Cu^II–O–Cu^II Motif: Spectroscopic Properties, Solution Structure, and Reactivity

et al. 2013

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We report a complex with a rare CuII–O–CuII structural motif that is stable at room temperature, which allows its in-depth characterization by a variety of spectroscopic methods. Interest in such compounds is fueled by the recent discovery that a CuII–O–CuII species on the surface of Cu-ZSM-5 is capable of oxidizing methane to methanol and this in turn ties into mechanistic discussions on the methane oxidation at the dicopper site within the particulate methane monooxygenase. For the synthesis of our Cu2O complex we have developed a novel, neutral ligand system, FurNeu, exhibiting two N-(N',N'-dimethylaminoethyl)(2-pyridylmethyl)amino binding pockets connected by a dibenzofuran spacer. The reaction of FurNeu with CuCl yielded [FurNeu](Cu2(μ-Cl))(CuCl2), 1, demonstrating the geometric potential of the ligand to stabilize Cu–X–Cu moieties. A CuI precursor with weakly coordinating anions was chosen in the next step, namely [Cu(NCCH3)4]OTf, which led to the formation of [FurNeu](Cu(NCCH3))2(OTf)2, 3. Treatment of 3 with O2 or PhIO led to identical green solutions, whose UV/Vis spectra were markedly different from the one displayed by [FurNeu](Cu)2(OTf)4, 4, prepared independently from FurNeu and Cu(OTf)2. Further investigations including PhIO consumption experiments, NMR and UV/Vis spectroscopy, HR-ESI mass spectrometry and protonation studies led to the identification of the green product as [FurNeu](Cu2(μ-O))(OTf)2, 5. DOSY NMR spectroscopy confirmed its monomeric character. Over longer periods of time 5 decomposes to give [Cu(picoloyl)2], formed through an oxidative N-dealkylation reaction followed by further oxidation of the ligand. Due to its slow decomposition reaction all attempts to crystallize 5 failed. However, its structure in solution could be determined by EXAFS analysis in combination with DFT calculations, which revealed a Cu–O–Cu angle that amounts to 105.17°. Moreover, TDDFT calculations helped to rationalize the UV/Vis absorptions of 5. The reactivity of complex 5 with 2,4-di-tert-butylphenol, DTBP, was also investigated; the initially formed biphenol product, TBBP, was found to further react in the presence of excessive O2 to yield 2,4,7,9-tetra-tert-butyloxepino[2,3-b]benzofuran, TBOBF, via an intermediate diphenoquinone, TBDQ. It turned out that 5, or its precursor 3, can even be employed as a catalyst for the oxidation of DTBP to TBBP or for the oxidation of TBBP to TBOBF.

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“…Symmetry was explicitly turned off for these computations even though all of the optimized structures belonged to the C 1 ‐point group. In addition to the procedures used to optimize the structures, the TD‐DFT computations were also performed with the CAM‐B3LYP, PBE0, and LC‐PBE functionals. The effects of solvation on the excited state transitions were modeled with PCM TD‐DFT calculations .…”

Section: Methodsmentioning

confidence: 99%

Indolizine‐Based Donors as Organic Sensitizer Components for Dye‐Sensitized Solar Cells

Huckaba

Giordano

McNamara

et al. 2014

Advanced Energy Materials

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Strong electron‐donating functionality is desirable for many organic donor‐π‐bridge‐acceptor (D‐π‐A) dyes. Strategies for increasing the electron‐donating strength of common nitrogen‐based donors include planarization of nitrogen substituents and the use of low resonance‐stabilized energy aromatic ring‐substituted nitrogen atoms. Organic donor motifs based on the planar nitrogen containing heterocycle indolizine are synthesized and incorporated into dye‐sensitized solar cell (DSC) sensitizers. Resonance active substitutions at several positions on indolizine in conjugation with the D‐π‐A π‐system are examined computationally and experimentally. The indolizine‐based donors are observed to contribute electron density with strengths greater than triarylamines and diarylamines, as evidenced by UV/Vis, IR absorptions, and oxidation potential measurements. Fluorescence lifetime studies in solution and on TiO2 yield insights in understanding the performance of indolizine‐based dyes in DSC devices.

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Long-range corrected DFT calculations of charge-transfer integrals in model metal-free phthalocyanine complexes

Cited by 21 publications

References 54 publications

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

Access to a Cu^II–O–Cu^II Motif: Spectroscopic Properties, Solution Structure, and Reactivity

Indolizine‐Based Donors as Organic Sensitizer Components for Dye‐Sensitized Solar Cells

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Long-range corrected DFT calculations of charge-transfer integrals in model metal-free phthalocyanine complexes

Cited by 21 publications

References 54 publications

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

Access to a CuII–O–CuII Motif: Spectroscopic Properties, Solution Structure, and Reactivity

Indolizine‐Based Donors as Organic Sensitizer Components for Dye‐Sensitized Solar Cells

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Product

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About

Access to a Cu^II–O–Cu^II Motif: Spectroscopic Properties, Solution Structure, and Reactivity