Intramolecular charge separation and recombination in non-polar environments via long-distance electron transfer through saturated hydrocarbon barriers

Warman, John M.; Smit, Kenneth J.; Jonker, Stephan A.; Verhoeven, J. W.; Oevering, Henk; Kroon, Jan; Paddon‐Row, Michael N.; Oliver, Anna M.

doi:10.1016/0301-0104(93)85119-s

Cited by 54 publications

(27 citation statements)

References 47 publications

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“…Structures obtained by molecular modeling (Figure S27) were used to estimate the donor–acceptor radius (r) and the details of the calculation of each correction term is provided in the Supporting Information (Table S3). Although the Weller equation is known to overestimate energies of the ion pair states by as much as 0.5 eV due to an overestimation for the destabilization of ion pairs in low polarity solvents, the energies calculated here are expected to provide reasonable energy level estimations. , …”

Section: Resultssupporting

confidence: 80%

“…Interestingly, comparison of the emission energies observed in DCM reveal that the experimental energy of the CT state is 0.2–0.25 eV lower than the value estimated from the Weller equation. Here, we note that the Weller equation has been shown to overestimate the CT energy by 0.5 eV in toluene, which has a polarity in-between hexane and DCM and fits the hypothesis that the estimations provided by the equation become increasingly more accurate with polar solvents. , …”

Section: Resultsmentioning

confidence: 99%

“…Although the Weller equation is known to overestimate energies of the ion pair states by as much as 0.5 eV due to an overestimation for the destabilization of ion pairs in low polarity solvents, the energies calculated here are expected to provide reasonable energy level estimations. 72,80 The calculated energies of the CT states in hexane and DCM for the T n NIF series are listed in the last two columns in Table 4 (E calc (solvent)). First, note that the calculated energy of the CT states in hexane range from 0.85 to 1 eV greater than the LE state energies determined from the fluorescence data (Table 4).…”

Section: The Journal Ofmentioning

confidence: 94%

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Fluorescent Charge-Transfer Excited States in Acceptor Derivatized Thiophene Oligomers

Jones

Schanze

2020

J. Phys. Chem. A

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A family of thiophene oligomers with lengths of 3, 4, 5, 6, and 8 units were synthesized and end-capped with a strongly coupled naphthalimide acceptor (T n NIF) which produces an emissive intramolecular charge-transfer state. A thorough photophysical study was performed on the oligomers including UV−vis absorption, fluorescence, and picosecond transient absorption spectroscopy to investigate the effect of thiophene oligomer length/donor strength and solvent polarity on the intramolecular charge-transfer properties. In hexane, the T n NIF compounds behave in a manner similar to that of oligothiophenes as fluorescence from a local singlet excited state and intersystem crossing to the triplet state dominates the excited-state dynamics. Interestingly, the excited-state dynamics become much more complicated with increasing solvent polarity, from ether to acetone, where emission from a charge-transfer state ( δ+ T n NIF −δ ) and quenching from a charge-separated state ( •+ T n NIF −• ) become competitive. A mechanism is proposed that consists of a four-state diagram including a locally excited singlet state ( 1 T n NIF), a triplet state ( 3 T n NIF), an emissive charge-transfer state, and a nonemissive charge-separated state. The population of each of these states is highly dependent on both the thiophene oligomer length and solvent polarity which results in a mixture of excited states.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: The Journal Ofmentioning

confidence: 94%

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Fluorescent Charge-Transfer Excited States in Acceptor Derivatized Thiophene Oligomers

Jones

Schanze

2020

J. Phys. Chem. A

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“…16 Direct observation of the singlet CT state is possible by virtue of its strongly solvatochromic CT fluorescence. 17 When the polarity of the solvent is increased, the energy gap becomes smaller and the reorganization energy larger, which strongly enhances charge recombination. In saturated hydrocarbon solvents the 1 CT-state lifetime is of the order of 2 ns, but this decreases to 420 ps in di-n-butyl ether, and in benzene, the most strongly solvating medium in which CT fluorescence could still be detected, it is as short as 6 ps.…”

Section: Charge Separation In the Excited States Of Dmn[3]dcme: Therm...mentioning

confidence: 99%

Spin control of the lifetime of an intramolecular charge-transfer excited state

Hviid

Bouwman

Paddon‐Row

et al. 2003

Photochem Photobiol Sci

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Triplet-sensitized generation of a long-lived intramolecular charge-separated excited state is described in an electron donor-acceptor molecule with a short distance between the donor and the acceptor. Time-resolved UV-Vis optical absorption spectroscopy shows that the lifetime of this triplet excited state is 1.4 micros in acetonitrile at 298 K, i.e. five orders of magnitude greater than that of the corresponding singlet charge-separated state. In slightly less polar alkane nitrile solvents, the local and CT triplet states coexist, which allows determination of their relative energies.

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“…There are also significant advances in synthesis of the supramolecular systems that mimic some functions of the photosynthetic reaction center [8,22,[33][34][35][36][37][38][39][40][41][42][43][44][45]. The goal is to achieve a long-lived and efficient charge separation between the distant subunits in an environment which differs from that in biological systems.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Charge Separation Processes in Supramolecular Triad Systems

Pirowska

Najbar

1998

Acta Phys. Pol. A

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The nonadiabatic electron transfers in donor-acceptor-acceptor systems are investigated using three potential energy surfaces and two reaction coordinates via the stochastic Lionville equation to describe time evolution of the three excited electronic states: (1) D*-A-A, (2) D+_A-A and (3) D+ -A-A. The electronic dephasing processes are taken into account phenomenologically in terms of dephasing constants. The couplings between surfaces are effective along the intersections of pairs of surfaces in the two-dimensional coordinate space. Special situations occur in the reaction coordinate space when three snrfaces are nearly degenerate. The interplay between the sequential electron transfer processes and the superexchange process is analysed for different: reorganization energies, electronic coupling, free energies for the electron transfer, dephasing rates, and temperature. The time dependent contribution of the superexchange process to the charge separation in the triad system is analysed using the time dependent rate functions. It is shown that in the nonadiabatic limit of electron transfer the influence of the electronic dephasing processes for low barrier reactions can be accounted for by appropriate changes in the reorganization energies. The present model is compared with the experimental results concerning the charge separation in the bacterial photosynthetic reaction centers.

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Intramolecular charge separation and recombination in non-polar environments via long-distance electron transfer through saturated hydrocarbon barriers

Cited by 54 publications

References 47 publications

Fluorescent Charge-Transfer Excited States in Acceptor Derivatized Thiophene Oligomers

Fluorescent Charge-Transfer Excited States in Acceptor Derivatized Thiophene Oligomers

Spin control of the lifetime of an intramolecular charge-transfer excited state

Photoinduced Charge Separation Processes in Supramolecular Triad Systems

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