Structural Changes Accompanying Intramolecular Electron Transfer:  Focus on Twisted Intramolecular Charge-Transfer States and Structures

Grabowski, Zbigniew R.; Rotkiewicz, Krystyna; Rettig, Wolfgang

doi:10.1021/cr940745l

Cited by 3,335 publications

(3,297 citation statements)

References 685 publications

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“…8 We examined this possibility for ap-ac by rotating about the terminial amine, using RHF/CIS energies. Twisting by 40°( relative to the symmetrical equilibrium local geometry at the amine) causes the S 1 state to rise 8.6 kcal/mol relative to the essentially coplanar minimum.…”

Section: Tictmentioning

confidence: 99%

A Theoretical Investigation of Charge Transfer in Several Substituted Acridinium Ions

Lappe¹,

Cave²,

Newton³

et al. 2005

J. Phys. Chem. B

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We present calculations for various properties of the ground and excited states of several arylamine-substituted acridinium ion systems that have been studied experimentally. Using ab initio and semiempirical quantum mechanical methods together with the generalized Mulliken-Hush (GMH) model, we examine the excitation energies, dipole moment shifts, and electronic coupling elements for the vertical charge shift (CSh) processes in these systems. We also examine solvent effects on these properties using a dielectric continuum reaction field model. The results are in generally good agreement with available experimental results and indicate that there is strong electronic coupling in these systems over a wide range of torsional angles. Nevetheless, the initial and final cationic states remain reasonably well-localized over this range, and thus TICT state formation is unlikely in these systems. Finally, a version of the GMH model based on Koopmans' Theorem is developed and found to yield coupling elements generally within a factor of 2 of the many-electron GMH for a sample acridinium system, but with overestimated adiabatic and diabatic dipole moment differences.

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Section: Tictmentioning

confidence: 99%

A Theoretical Investigation of Charge Transfer in Several Substituted Acridinium Ions

Lappe¹,

Cave²,

Newton³

et al. 2005

J. Phys. Chem. B

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“…Applications range from labeling proteins or DNA [1] to monitoring physiological processes, such as calcium channel activation, biomolecular interactions [2], or biophysical changes in the cell membrane [3]. Environment sensitivity predominantly depends on the interaction of a fluorophore dipole with its environment (e.g., solvatochromic shifts in environments of different polarity [4]), direct fluorophore-solvent interaction (e.g., quenching or hydrogen bond formation [5]), fluorophorefluorophore interaction, and segmental mobility [6]. In fact, Lakowicz raises the concern that multiple simultaneous interactions create a complex spectral behavior that is difficult to attribute to one single environmental effect [1].…”

Section: Introductionmentioning

confidence: 99%

“…Of particular interest are some dyes with segmental mobility that are capable of an intramolecular twisting motion in the excited state [6], which are often referred to as "molecular rotors" [7,8]. Those molecules have two competing deexcitation pathways: (a) a pathway in which the molecule remains in a planar conformation when it returns to the ground state, and (b) a pathway in which the molecule assumes a twisted state before returning to the ground state.…”

Section: Introductionmentioning

confidence: 99%

“…The choice of 3 was made to exclude the possibility that the carboxylic acid of 2 undergoes ester formation with the solvent. In addition, we examined 9-(dicarboxyvinyl)-julolidine (6) to differentiate between the influence of polar headgroups (such as the carboxyl group of 2, which is absent in 1) and the influence of a symmetrical headgroup that is unable to form isomers as in the case of 1.…”

Section: Introductionmentioning

confidence: 99%

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Apparent Shear Sensitivity of Molecular Rotors in Various Solvents

et al. 2015

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Fluorescent environment-sensitive dyes often change their spectral properties concomitantly with multiple solvent properties, such as polarity, protonation, hydrogen bond formation, or viscosity. Careful consideration of the response is needed when a fluorescent dye is used to report a single property. Recently, we observed an increase of emission intensity of viscosity-sensitive molecular rotors in fluids subject to flow and speculated that either polar-polar interaction or hydrogen bond formation play a role in the apparent flow sensitivity. In this study, we show experimental evidence that photoisomerization to an isomer with a lower quantum yield, first proposed by Rumble et al. (J Phys Chem A 116(44):10786-10792, 2012), plays a key role in the observed phenomenon. We subjected four molecular rotors with different electron acceptor motifs to fluid flow in solvents of different polarity and ability to form hydrogen bonds. We also measured the isomerization dynamics in a custom fluorophotometer with extremely low light exposure. Our results indicate that the photoisomerization rate depends both on the solvent and on the electron acceptor group, as does the recovery of the original isomer in the dark. In most solvents, recovery of the dark isomer is much more rapid than originally reported, and a state of quasiequilibrium between both isomers is possible. Moreover, the sensitivity (i.e., relative intensity increase at the same flow rate) is also solvent-dependent. The intensity increase can be detected at very low velocities (as low as 0.06 mm/s). Characteristic for fluorescent dyes is the high spatial resolution, and no flow measurement device with comparable sensitivity and spatial resolution exists, although the nature of the solvent needs to be taken into account for quantitative flow measurement.

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“…30,32 The theoretical calculations are especially important for the understanding of the excited state behavior of the molecule since the experimental mapping of the deactivation channels is hampered by the short lifetime of the first excited state.…”

mentioning

confidence: 99%

Solvation and Protonation of Coumarin 102 in Aqueous Media: A Fluorescence Spectroscopic and Theoretical Study

et al. 2014

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Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

Cited by 3,335 publications

References 685 publications

A Theoretical Investigation of Charge Transfer in Several Substituted Acridinium Ions

A Theoretical Investigation of Charge Transfer in Several Substituted Acridinium Ions

Apparent Shear Sensitivity of Molecular Rotors in Various Solvents

Solvation and Protonation of Coumarin 102 in Aqueous Media: A Fluorescence Spectroscopic and Theoretical Study

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