Prediction of Two-Photon Absorption Properties for Organic Chromophores Using Time-Dependent Density-Functional Theory

Masunov, Artëm E.; Tretiak, Sergei

doi:10.1021/jp036513k

Cited by 182 publications

(221 citation statements)

References 68 publications

(164 reference statements)

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“…88 For ground state geometries, we previously found that the Hartree-Fock (HF) method is superior to the DFT-based approaches by reproducing accurately bond length alternation parameters in similar conjugated systems when compared to experiment. 63,89 Moreover, excited state geometry optimizations 90,91 of substituted chromophores may fail due to long-range charge-transfer problems present in DFT. [92][93][94][95] Thus, all ground state geometries are obtained at the HF level using the 6-31G basis set.…”

Section: Methodsmentioning

confidence: 99%

“…This method has already demonstrated its accuracy (within a factor of 6) for both linear and nonlinear absorption spectra in different series of substituted chromophores. 57,63,89,100 Excited state electronic structures, with 20 excited states for compounds 1-3 and up to 54 for compound 4, were calculated with Gaussian 98 and 03, respectively. 88 Vertical transition frequencies (Ω gν ), dipoles (µ gν ), and densities ( gν ) are used to model both linear absorption and TPA spectra.…”

Section: Methodsmentioning

confidence: 99%

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Two-Photon Transitions in Quadrupolar and Branched Chromophores: Experiment and Theory

et al. 2007

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A combined experimental and theoretical study is conducted on a series of model compounds in order to assess the combined role of branching and charge symmetry on absorption, photoluminescence, and twophoton absorption (TPA) properties. The main issue of this study is to examine how branching of quadrupolar chomophores can lead to different consequences as compared to branching of dipolar chromophores. Hence, three structurally related π-conjugated quadrupolar chromophores symmetrically substituted with donor end groups and one branched structure built from the assembly of three quadrupolar branches via a common donor moiety are used as model compounds. Their photophysical properties are studied using UV-vis spectroscopy, and the TPA spectra are determined through two-photon excited fluorescence experiments using femtosecond pulses in the 500-1000 nm range. Experimental studies are complemented by theoretical calculations. The applied theoretical methodology is based on time-dependent density functional theory, the Frenkel exciton model, and analysis in terms of the natural transition orbitals of relevant electronic states. Theory reveals that a symmetrical intramolecular charge transfer from the terminal donating groups to the middle of the molecule takes place in all quadrupolar chromophores upon photoexcitation. In contrast, branching via a central electron-donating triphenylamine moiety breaks the quadrupolar symmetry of the branches. Consequently, all Frank-Condon excited states have significant asymmetric multidimensional charge-transfer character upon excitation. Subsequent vibrational relaxation of the branched chromophore in the excited state leads to a localization of the excitation and fluorescence stemming from a single branch. As opposed to what was earlier observed when dipolar chromophores are branched via the same common electron-donating moiety, we find only a slight enhancement of the maximum TPA response of the branched compound with respect to an additive contribution of its quadrupolar branches. In contrast, substantial modifications of the spectral shape are observed. This is attributed to the subtle interplay of interbranch electronic coupling and asymmetry caused by branching.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Two-Photon Transitions in Quadrupolar and Branched Chromophores: Experiment and Theory

et al. 2007

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“…We use the B3LYP functional combined with the 6-31G basis set as implemented in the Gaussian 98 package [27]. The 6-31G basis set is known to be an efficient blend of accuracy and manageable size for large conjugated molecules [29].…”

Section: Computational Methodologymentioning

confidence: 99%

A joint theoretical and experimental study of phenylene–acetylene molecular wires

Magyar

Tretiak

Gao

et al. 2005

Chemical Physics Letters

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The excited state electronic structure of π conjugated phenylene-acetylene oligomers is calculated using time-dependent density functional theory (TD-DFT) approaches. The theoretical fluorescence spectra are analyzed in terms of Frank-Condon active nuclear normal modes and shown to compare well with experiment. Theoretical and experimental results for the optical absorption and emission spectra of these molecules indicate that the conjugation length can be significantly reduced by conformational rotations about the triple-bonded carbon links. This has serious implications on the electronic functionalities of polyphenylene-acetylene based molecular wires and their possible use as charge/energy conduits in nano-assemblies.

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“…The SV and similar 6-31G basis sets are known to be an efficient blend of accuracy and manageable size for large conjugated molecules. 48 For the thiophenes and chlorophyll calculations we used geometries extracted from the experimental X-ray crystallographic data. 49,50 In addition to the single molecule limit, we consider thiophene dimers (2Th4) generated from the coordinates of two nearest neighbor pairs in the unit cell.…”

Section: Introductionmentioning

confidence: 99%

Dependence of Spurious Charge-Transfer Excited States on Orbital Exchange in TDDFT: Large Molecules and Clusters

Magyar

Tretiak

2007

J. Chem. Theory Comput.

297

276

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Time-dependent density functional theory (TDDFT) is a powerful tool allowing for accurate description of excited states in many nanoscale molecular systems; however, its application to large molecules may be plagued with difficulties that are not immediately obvious from previous experiences of applying TDDFT to small molecules. In TDDFT, the appearance of spurious charge-transfer states below the first optical excited state is shown to have significant effects on the predicted absorption and emission spectra of several donor-acceptor substituted molecules. The same problem affects the predictions of electronic spectra of molecular aggregates formed from weakly interacting chromophores. For selected benchmark cases, we show that today's popular density functionals, such as purely local (Local Density Approximation, LDA) and semilocal (Generalized Gradient Approximation, GGA) models, are qualitatively wrong. Nonlocal hybrid approximations including both semiempirical (B3LYP) and ab initio (PBE1PBE) containing a small fraction (20-25%) of Fock-like orbital exchange are also susceptible to such problems. Functionals that contain a larger fraction (50%) of orbital exchange like the early hybrid (BHandHLYP) are shown to exhibit far fewer spurious charge-transfer (CT) states at the expense of accuracy. Based on the trends observed in this study and our previous experience we formulate several practical approaches to overcome these difficulties providing a reliable description of electronic excitations in nanosystems.

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Prediction of Two-Photon Absorption Properties for Organic Chromophores Using Time-Dependent Density-Functional Theory

Cited by 182 publications

References 68 publications

Two-Photon Transitions in Quadrupolar and Branched Chromophores: Experiment and Theory

Two-Photon Transitions in Quadrupolar and Branched Chromophores: Experiment and Theory

A joint theoretical and experimental study of phenylene–acetylene molecular wires

Dependence of Spurious Charge-Transfer Excited States on Orbital Exchange in TDDFT: Large Molecules and Clusters

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