Two-Directional Photoinduced Electron Transfer in a Trichromophoric System

Depaemelaere, S.; Schryver, F. C. De; Verhoeven, J. W.

doi:10.1021/jp980039e

Cited by 13 publications

(5 citation statements)

References 54 publications

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“…The electronic structure of the amino analogue T-2 indicates the occurrence of a CT transition close in energy to that of the B-curcuminoid chromophore, which is confirmed by electronic absorption spectroscopy. Dual fluorescence in (T)ICT molecules, including T-shaped species, has already been observed, − ,,,− but it classically arose from the locally excited and CT states of the same chromophore. Unlike those previous cases, compound T-2 exhibits two close-lying singlet excited states with distinct CT strengths that belong to separate chromophoric branches and can be photoexcited independently.…”

Section: Discussionmentioning

confidence: 99%

“…In that connection, molecular cruciforms − ,, and T-shaped systems , having ICT transitions were investigated as fluorescence polarity indicators or metal ion sensors. Moreover, dual fluorescence was observed in several D–A systems owing to the interplay between locally excited (LE) and charge transfer (CT) states. , In some cases, a more complex photophysics resulted from the occurrence of two CT states. − This effect was due to the existence of a distribution of excited rotamers leading to differently relaxed CT species with identical orientations of their excited-state dipole moment. As a result, a direct filiation of relaxation between CT states was evidenced.…”

Section: Introductionmentioning

confidence: 99%

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Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad

et al. 2015

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Controlling photoinduced intramolecular charge transfer at the molecular scale is key to the development of molecular devices for nanooptoelectronics. Here, we describe the design, synthesis, electronic characterization, and photophysical properties of two electron donor-acceptor molecular systems that consist of tolane and BF2-containing curcuminoid chromophoric subunits connected in a T-shaped arrangement. The two π-conjugated segments intersect at the electron acceptor dioxaborine core. From steady-state electronic absorption and fluorescence emission, we find that the photophysics of the dialkylamino-substituted analogue is governed by the occurrence of two closely lying excited states. From DFT calculations, we show that excitation in either of these two states results in a distinct shift of the electron density, whether it occurs along the curcuminoid or tolane moiety. Femtosecond transient absorption spectroscopy confirmed these findings. As a consequence, the nature of the emitting state and the photophysical properties are strongly dependent on solvent polarity. Moreover, these characteristics can also be switched by protonation or complexation at the nitrogen atom of the amino group. These features set new approaches toward the construction of a three-terminal molecular system in which the lateral branch would transduce a change of electronic state and ultimately control charge transport in a molecular-scale device.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad

et al. 2015

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“…This arrangement is analogous to an acceptor-donor-acceptor system capable of two-directional photoinduced electron transfer. [40] The distribution of the two ICT pathways in the current system, as described in later sections, is governed by factors that include the electron density of the donor (D) and the relative electronegativities of the two acceptors.…”

Section: Molecular Designmentioning

confidence: 99%

Tunable Dual Fluorescence of 3‐(2,2′‐Bipyridyl)‐Substituted Iminocoumarin

Younes¹,

Zhu²

2012

ChemPhysChem

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3-(2,2'-Bipyridyl)-substituted iminocoumarin molecules (compounds 1 and 2) exhibit dual fluorescence. Each molecule has one electron donor and two electron acceptors that are in conjugation, which leads to fluorescence from two independent charge transfer (CT) states. To account for the dual fluorescence, we subscribe to a kinetic model in which both CT states form after rapid decays from the directly accessed S(1) and S(2) excited states. Due to the slow internal conversion from S(2) to S(1), or more likely the slow interconversion between the two subsequently formed CT states, dual emission is allowed to occur. This hypothesis is supported by the following evidence: 1) the emission at short and long ends of the spectrum originates from two different excitation spectra, which eliminates the possibility that dual emission occurs after an adiabatic reaction at the S(1) level. 2) The fluorescence quantum yield of compound 2 grows with increasing excitation wavelength, which indicates that the high-energy excitation elevates the molecule to a weakly emissive state that does not internally convert to the low-energy, highly emissive state. The intensity of the two emission bands of 1 is tunable through the specific interactions between either of the two electron acceptors with another species, such as Zn(2+) in the current demonstration. Therefore, the development of ratiometric fluorescent indicators based on the dual-emitting iminocoumarin system is conceivable. Further fundamental studies on this series of compounds using time-resolved spectroscopic techniques, and explorations of their applications will be carried out in the near future.

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“…9) is another example where directionality in an electron transfer event is an issue, and it consists of two cyano-based electron acceptors and donor in a A 1 -D-A 2 linear fashion. 30 Within the molecule there exists a competition between electron transfer mechanisms using the s-bond framework or the p-way. The central donor portion of 20 is part of the initially formed excited state and so electron transfer can occur in two directions.…”

Section: Metal-based Complexesmentioning

confidence: 99%

Pushing around electrons: towards 2-D and 3-D molecular switches

Benniston

2004

Chem. Soc. Rev.

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In the new age of molecular electronics there has been a great deal of speculation about ways to control the passage of electrons through organic-based wires using electro- or photo-active switches. However, the next stage development is envisaged as the added sophistication of directionality so that electron migration can be switched into 2 and 3 dimensions. This short tutorial review will set out how this realisation may be achieved and highlight examples where the idea of directionality in electron transfer has been put into practice.

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Two-Directional Photoinduced Electron Transfer in a Trichromophoric System

Cited by 13 publications

References 54 publications

Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad

Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad

Tunable Dual Fluorescence of 3‐(2,2′‐Bipyridyl)‐Substituted Iminocoumarin

Pushing around electrons: towards 2-D and 3-D molecular switches

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