Coherent Effects in Energy Transport in Model Dendritic Structures Investigated by Ultrafast Fluorescence Anisotropy Spectroscopy

Varnavski, Oleg; Ostrowski, Jacek C.; Сухомлинова, Л. И.; Twieg, Robert J.; Bazan, Guillermo C.

doi:10.1021/ja011038u

Cited by 183 publications

(285 citation statements)

References 58 publications

(74 reference statements)

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“…26 This may be another reason for the larger spectral red shift observed in chromophore 4. Goodson et al also showed that, for the D−π−A−π−D structure, replacement of a single bond by a double bond led to a larger red shift both in absorption and fluorescence than that by triple bond, 18,54,59 which is consistent with our experimental results. Moreover, similar phenomenon has also been observed in our previous study in which the branched chromophore, which formed by a simple unconjugated combination of two or three D−π−A−π−D moieties, showed only very small alteration in spectral features compared to the monomers, 12,28 whereas the chromophore formed by conjugated moieties, which have π bridge linkers, usually have a remarkable delocalized ICT state, and therefore, significantly different spectral features from those of isolated moieties.…”

supporting

confidence: 92%

Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives

Yan

Chen

et al. 2012

J. Phys. Chem. A

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In order to better understand the nature of intramolecular charge and energy transfer in multibranched molecules, we have synthesized and studied the photophysical properties of a monomer quadrupolar chromophore with donor−acceptor−donor (D−A−D) electronic push−pull structure, together with its V-shaped dimer and star-shaped trimers. The comparison of steady-state absorption spectra and fluorescence excitation anisotropy spectra of these chromophores show evidence of weak interaction (such as charge and energy transfer) among the branches. Moreover, similar fluorescence and solvation behavior of monomer and branched chromophores (dimer and trimer) implies that the interaction among the branches is not strong enough to make a significant distinction between these molecules, due to the weak interaction and intrinsic structural disorder in branched molecules. Furthermore, the interaction between the branches can be enhanced by inserting π bridge spacers (−CC− or −CC−) between the core donor and the acceptor. This improvement leads to a remarkable enhancement of two-photon cross-sections, indicating that the interbranch interaction results in the amplification of transition dipole moments between ground states and excited states. The interpretations of the observed photophysical properties are further supported by theoretical investigation, which reveal that the changes of the transition dipole moments of the branched quadrupolar chromophores play a critical role in observed the two-photon absorption (2PA) cross-section for an intramolecular charge transfer (ICT) state interaction in the multibranched quadrupolar chromophores.

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supporting

confidence: 92%

Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives

Yan

Chen

et al. 2012

J. Phys. Chem. A

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“…The excitation localization on one branch of a trimeric system has already been proven by photophysical experiments conducted on octupolar derivatives built from the TPAmine core 61,63,71 and on three-branched systems and conjugated dendrimers built from various joints/ cores. [61][62][63]70,77 4.2. Two-Photon Absorption.…”

Section: Geometry and Nature Of The Excited Statesmentioning

confidence: 99%

“…63,71,72 It should be noted that experimental evidence of the localization of the excitation on a single branch prior to emission has been given for various branched systems built from a TPBenzene core. [75][76][77][78] The aim of this work is to explore experimentally and theoretically how photophysical and TPA properties are modified by branching via a TPAmine core quadrupolar chromophores instead of dipolar chromophores. In that perspective, we first focus on the fluorescence and the one-photon absorption (OPA) and two-photon absorption (TPA) of a series of symmetrical quadrupolar chromophores bearing electron-donating end groups.…”

Section: Introductionmentioning

confidence: 99%

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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“…The value is also decrease with increase of number of branches. Usually, large initial anisotropy value as well as fast decay indicates strong intramolecular interactions which directly affect energy redistributions and bring large nonlinear optical effect [10]. This may be a reason why TPA cross section of trimer T03 is is about 5.32-fold larger than that of monomer T01, the anisotropy decay time is shorter than that of monomer T01.…”

Section: Resultsmentioning

confidence: 99%

“…It has been widely used in experiments on photosynthetic reaction center. Goodson et al reported plenty of significant results based on time-resolved fluorescence up-conversion measurement on optical dendrimers [10][11]. Dynamics of molecules with two-photon absorption properties are, however, still inadequate especially for the conjugated molecules.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved fluorescence anisotropy study on intramolecular interactions of branched styryl derivatives based on 1,3,5-triazine

Wang¹,

Wang²,

Liu³

et al. 2015

Proceedings of the 2015 International Conference on Power Electronics and Energy Engineering

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Abstract-A series of branched styryl derivatives based on 1, 3, 5-triazine have been studied by time-resolved fluorescence anisotropy method to study the intramolecules interferaction between branches. The obtained results further confirmed the TPA enhancement mechanism, the anisotropy of trimer shows faster decay and small residual value indicates there are strong intramolecules interactions among branches, this maybe the enhancement mechanism of TPA properties for the trimer.

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Coherent Effects in Energy Transport in Model Dendritic Structures Investigated by Ultrafast Fluorescence Anisotropy Spectroscopy

Cited by 183 publications

References 58 publications

Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives

Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives

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

Time-resolved fluorescence anisotropy study on intramolecular interactions of branched styryl derivatives based on 1,3,5-triazine

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