Electronic Structures of Exciplexes and Excited Charge-Transfer Complexes

Gould, Ian R.; Young, Ralph H.; Mueller, Leonard J.; Albrecht, A. C.; Farid, Samir

doi:10.1021/ja00097a028

Cited by 241 publications

(312 citation statements)

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“…Solvent has also been implicated in controlling the electronic coupling in systems containing solvent-separated ion pairs. 16 In addition, a number of rigidly linked donor-acceptor pairs, in particularly favorable geometries, have also shown evidence of solvent-enhanced electronic coupling. 13,17,18 A number of theoretical studies have also examined the effects of solvent on the electronic coupling.…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Study of the Electronic Coupling Element for Electron Transfer in Water

1999

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The electronic coupling element for electron transfer between a donor and acceptor in water is examined using simulations combining molecular dynamics and semiempirical quantum mechanics. In the first phase of the simulations a model donor and acceptor are solvated in water, using realistic potentials. Following equilibration, molecular dynamics simulations are performed with the donor, acceptor, and water at approximately 300 K, under periodic boundary conditions. In the second phase of the simulation, the electronic coupling element between the donor and acceptor is calculated for a number of time slices, in the presence of the intervening water molecules (those having a nonnegligible effect on the coupling element at the given distance). Finally, a subset of these configurations is used to investigate the donor-acceptor energy dependence of the coupling by varying the model donor and acceptor. It is found, contrary to a number of previous theoretical results, that water significantly increases the electronic coupling element at a given donor-acceptor separation. The value for using INDO wave functions is estimated to be 2.0 Å -1 and is found to depend weakly on the identity of the donor and acceptor. Comparison with ab initio results for a subset of the configurations or using idealized solvent geometries suggests that the ab initio value would be in the range of 1.5-1.8 Å -1 .

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Section: Introductionmentioning

confidence: 99%

A Theoretical Study of the Electronic Coupling Element for Electron Transfer in Water

1999

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“…A ratio M 2 2 =M 2 1 of ca. 0.1 (M 2 ¼ 2:8 to 2:9 D) was found for exciplexes with 9,10-dicyanoanthracene (DCA) and 2,6,9,10-tetracyanoanthracene (TCA) with methylbenzenes [2]. The z values were found from the dependence of the exciplex emission spectral shift relative to that of the parent electron acceptor hDm in our previous works [13,14] 1.6 eV).…”

Section: Exciplex Emission Rate Constants K 0 Fmentioning

confidence: 85%

“…The dependence of the emission rate constants on the degree of charge transfer in the exciplexes z was discussed by several authors in terms of intensity borrowing by the exciplex CT transition from the transition to the ground state from lower LE state of the fluorescer [26][27][28]. Gould et al [2] have taken into account the orthogonality of vectors of radiative transition dipole moments from the LE (M 1 ) and CT (M 2 ) states, and have given a simple expression for the relationship between (k 0 F =k F ) and z: where m 0 Av and m Av are the average emission frequencies of exciplex and electron acceptor [15,16]. A ratio M 2 2 =M 2 1 of ca.…”

Section: Exciplex Emission Rate Constants K 0 Fmentioning

confidence: 99%

“…Exciplexes with partial charge transfer are formed in non-polar as well as in polar solvents when the driving force of excited-state electron transfer (ET) is small (DG Ã ET > À0:5 eV) [1][2][3][4][5][6][7][8][9][10]. An important feature of these exciplexes is a variable degree of charge transfer (z) which depends on both DG Ã ET and medium polarity [11][12][13][14] [1,2,15] and a nonlinear dependence of the exciplex emission frequency on the medium polarity [11][12][13][14][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…An important feature of these exciplexes is a variable degree of charge transfer (z) which depends on both DG Ã ET and medium polarity [11][12][13][14] [1,2,15] and a nonlinear dependence of the exciplex emission frequency on the medium polarity [11][12][13][14][16][17][18][19]. These effects allow to evaluate z from experimental dependence the of the exciplex emission frequency on solvent polarity [11][12][13][14]16,17] or from the values of k 0 F ¼ ðu 0 =s 0 0 Þðu 0 =uÞ=ðu 0 =u À 1Þ (where u 0 and u are the fluorescence quantum yields of the exciplex and parent excited molecules in the presence of the quencher, respectively, u 0 is the fluorescence quantum yield of the parent excited molecules in the absence of quencher; s 0 0 is the exciplex lifetime) [1,2,11].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Lifetimes of partial charge transfer exciplexes of 9-cyanophenanthrene and 9-cyanoanthracene

Dolotova

Dogadkin

Соболева

et al. 2003

Chemical Physics Letters

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The fluorescence decays of several exciplexes with partial charge transfer have been investigated in solvents of various polarity. The measured lifetimes are found to be in reasonable agreement with the activation enthalpy and entropy of exciplex decay obtained earlier from the temperature dependence of the exciplex emission quantum yields. For exciplexes with 9-cyanophenanthrene substantial contribution of the higher local excited state into the exciplex electronic structure is found and borrowed intensity effect enhances the exciplex emission rate constants.

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Exploring the Limits of the Electrostatically Induced Conformational Folding Process in Charge-Separated Excited States: Retarding Effect of Long Alkyl Tails Attached to the Chromophores

et al. 1998

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Six new donor‐bridge‐acceptor compounds have been synthesized which contain a long n‐tetradecyl chain attached to the donor or acceptor moiety, or to both of them. Systems 1, 2, and 3 are analogs of the fluorescent probe molecule Fluoroprobe (4). They contain a rigidly extended 4‐methylenepiperidine bridge and show relatively strong charge transfer fluorescence in solvents of low and medium polarity. Systems 1a, 2a, and 3a contain a semiflexible 4‐methylpiperidine bridge, obtained after hydrogenation of the exocyclic double bond of 1, 2 and 3, respectively. These systems undergo a conformational change following photoinduced charge separation (“harpooning”) in nonpolar solvents and probably also in solvents of medium polarity. Both the steady state fluorescence spectra and the fluorescence decay times of the extended charge transfer (ECT) species show that the photoinduced folding process is effectively slowed down by the introduction of the long alkyl tails. This is most pronounced for 1a which has an n‐tetradecyl group attached to both donor and acceptor. In solution a small difference in the rate of folding is observed between 2a and 3a, which have a single n‐tetradecyl chain attached to the acceptor only and to the donor only, respectively.

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Electronic Structures of Exciplexes and Excited Charge-Transfer Complexes

Cited by 241 publications

References 3 publications

A Theoretical Study of the Electronic Coupling Element for Electron Transfer in Water

A Theoretical Study of the Electronic Coupling Element for Electron Transfer in Water

Lifetimes of partial charge transfer exciplexes of 9-cyanophenanthrene and 9-cyanoanthracene

Exploring the Limits of the Electrostatically Induced Conformational Folding Process in Charge-Separated Excited States: Retarding Effect of Long Alkyl Tails Attached to the Chromophores

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