Intramolecular Charge Transfer as Revealed by Results from the Measurement of Ground and Excited State Dipole Moments

Baumann, Wolfram; Nagy, Zsolt László; Maiti, A. K.; Reis, Heribert; Rodrigues, Silvana Vianna; Detzer, N.

doi:10.1016/b978-0-444-89191-4.50022-7

Cited by 11 publications

(15 citation statements)

References 25 publications

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“…Weber and Farris postulate in their original hypothesis 1 an excited-state dipole moment 5 times larger than the ground-state dipole moment (see Table ). This ratio is ruled out in the meantime, ,,, but neither the ground- nor excited-state dipole moments are ascertained yet, as can be seen in Table . The measurement of excited-state dipole moments is quite difficult and depends also on several assumptions, e.g., an arbitrary Onsager radius and the continuum dielectric model of the solvent.…”

Section: Resultsmentioning

confidence: 94%

“…Interpretation of PRODAN Fluorescence Spectrum. The large Stokes shift for PRODAN in polar solvents has been investigated by time-resolved , and temperature- 45 and pressure 46 -dependent fluorescence spectroscopy as well as electrooptical absorption and emission measurements, and the general conclusion of all investigations clearly votes for the existence of an intramolecular charge transfer state. In addition, dual fluorescence is observed at low temperatures and in a highly viscous environment .…”

Section: Resultsmentioning

confidence: 99%

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Comparative Theoretical Study on Charge-Transfer Fluorescence Probes: 6-Propanoyl-2-(N,N-dimethylamino)naphthalene and Derivatives

et al. 1998

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The efficient fluorescence probe 6-propanoyl-2-(N,N-dimethylamino)naphthalene (PRODAN) shows a significant Stokes shift in polar solvents. Neither experimental nor theoretical studies performed up to now yield a definitive description of the character of the emissive state. Results of the recently developed DFT/ SCI method are compared to semiempirical calculations with the spectroscopic ZINDO/S parametrization and the AM1/CISD Hamiltonian which was not parametrized for computation of spectroscopic properties. The most reliable results are obtained with the DFT/SCI and AM1/CISD approaches. The absorption spectrum of PRODAN is excellently reproduced by the DFT/SCI calculations, and the AM1/CISD results are superior to ZINDO/S. These results allow the assignment of the red-shifted fluorescence band to both emission of a highly polar dimethylamino twisted intramolecular charge transfer state (N-TICT) and a geometrically unchanged planar intramolecular charge transfer (PICT) state. A comparison with 2-(N,N-dimethylamino)naphthalene (DAN) and 2-propanoylnaphthalene (PRON) shows that each of the donor or acceptor substituents alone in combination with rotation about the naphthalene-substituent single bond is sufficient to generate a low lying charge-transfer state with a large dipole moment.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Comparative Theoretical Study on Charge-Transfer Fluorescence Probes: 6-Propanoyl-2-(N,N-dimethylamino)naphthalene and Derivatives

et al. 1998

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“…The same experimental setup for IEOEM was employed as was reported elsewhere. ,, The solution was excited by a high-pressure mercury lamp (500 W). The fluorescence photon current was detected by a photomultiplier placed on the perpendicular against the excitation axis.…”

Section: Methodsmentioning

confidence: 99%

“…One of the other methods to determine μ e is IEOEM, utilizing the fluorescence anisotropy induced by an external electric field. Elaborated theoretical and experimental details have been described by Liptay and Baumann. ,− Here the theoretical model is briefly surveyed. According to Onsager's model, under the influence of an externally applied electric field E a , the electric field inside the cavity E i is related to E a as with In a solute−solvent system, the energy of the system is considered to be distributed, reflecting the different degree of the orientational distribution of solvent molecules around the solute molecule.…”

Section: Theoretical Backgrounds On Dipole Moments In the Excited Statementioning

confidence: 99%

Electronic Structures of 9,10-Anthrylene Dimers and Trimers in Solution: Formation of Charge Separation States Depending on Alkyl Substituent Groups

et al. 1998

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Electronic structures of 9,10-anthrylene dimers and trimers analogous to 9,9‘-bianthryl (BA) have been investigated by means of steady-state fluorescence and transient absorption spectroscopy and dipole moment evaluation based on the solvatochromic fluorescence shifts and integrated electrooptical emission measurements (IEOEM) in various solvents. Formation of the charge-separation (CS) state in the excited state was strongly dependent on the substituent group: unsubstituted and n-hexyl-substituted anthrylenes exhibited almost the same behavior compared to BA, whereas the tert-butyl-substituted dimer and trimer relaxed into an excitonic state rather than the CS state even in a polar solvent. The lower possibility of the CS state for the tert-butyl-substituted anthrylenes was mainly ascribed to the smaller solvation energy because of the larger effective Onsager cavity due to bulky tert-butyl groups. The limitation of a simple continuum model using Onsager's reaction field was also discussed in relation to the solvent-induced electronic structure change in the excited state of anthrylenes.

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“…The emission maximum of a dipolar excited state as a function of solvent polarity can be described by the following equation: − ṽ ct and correspond respectively to the wavenumber of the emission maximum in a solvent with dielectric constant ε and refractive index n and the wavenumber of the emission maximum in the gas phase. ε 0 , h , c , and ρ correspond to the permittivity of vacuum, the Planck constant, the velocity of light in vacuum, and the Onsager radius for the solvent cavity.…”

Section: Resultsmentioning

confidence: 99%

Two-Directional Photoinduced Electron Transfer in a Trichromophoric System

1998

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Competition between electron transfer via a through σ-bond and a through π-bond mechanism has been studied in 1-(4-cyanophenyl)-4-(cyanomethylene)piperidine. In this trichromophoric system designed in a configuration acceptor-donor-acceptor, where the donor chromophore is part of the initially excited state, electron transfer occurs in two directions. The results of the single-photon-timing measurements indicate that, in both diethyl ether and acetonitrile, two charge-transfer states, a σCT and a πCT state, are formed, by transferring the electron through the σ-or π-bonds, respectively. Information on the excited-state kinetics is obtained by means of global compartmental analysis of the fluorescence decay surface in acetonitrile. Both the σCT and πCT state are formed immediately upon excitation, within the time resolution of the experimental setup, and an electron exchange between the two polar states occurs at least in one direction.

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Intramolecular Charge Transfer as Revealed by Results from the Measurement of Ground and Excited State Dipole Moments

Cited by 11 publications

References 25 publications

Comparative Theoretical Study on Charge-Transfer Fluorescence Probes: 6-Propanoyl-2-(N,N-dimethylamino)naphthalene and Derivatives

Comparative Theoretical Study on Charge-Transfer Fluorescence Probes: 6-Propanoyl-2-(N,N-dimethylamino)naphthalene and Derivatives

Electronic Structures of 9,10-Anthrylene Dimers and Trimers in Solution: Formation of Charge Separation States Depending on Alkyl Substituent Groups

Two-Directional Photoinduced Electron Transfer in a Trichromophoric System

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