Spectral relaxation of the benzophenone negative ion in alcohol glasses: Evidence for solvent reorientation

Huddleston, R. Kurt; Miller, John R.

doi:10.1016/0146-5724(81)90039-x

Cited by 10 publications

(8 citation statements)

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“…Comparison with Experiments . The energy size of the spectral shift was 0.41 eV in the present calculation, which is close to the experimental values (0.32−0.38 eV), , although the excitation energies were slightly underestimated in the PM3-CI calculations. A more accurate wave function (e.g., ab initio CI calculation with large basis sets) may be required to obtain a more realistic excitation energy.…”

Section: Discussionsupporting

confidence: 86%

“…The origin of the spectral shifts in anion radicals of the CO carbonyl compounds has not been clearly understood as compared with the neutral systems. Huddleson and Miller observed the time dependent absorption spectra of the benzophenone radical anion (Bp - ) in ethanol by means of the pulse radiolysis technique. They found that the spectrum of the benzophenone anion generated by pulse irradiation is shifted as a function of time.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Spectral Shift of Benzophenone Radical Anion Caused by the Solvent Molecule Reorientation. Semiempirical PM3-MO and Classical Trajectory Studies

Tachikawa

1996

J. Phys. Chem.

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The spectral shifts for the first electronic transition of the benzophenone anion radical (Bp -) caused by solvent geometrical reorientation have been investigated by means of semiempirical PM3-MO and classical trajectory calculations. A methanol molecule (MeOH) and the complex composed of Bp -and a methanol molecule (Bp -‚‚‚MeOH complex) were chosen as a solvent molecule and a solvated reaction system, respectively. The classical trajectories of the Bp -‚‚‚MeOH complex following vertical electron attachment to the neutral system have been calculated by the Runge-Kutta method on the PM3 multidimensional potential energy surfaces. The calculations suggested that the solvation structure of the neutral Bp‚‚‚MeOH complex is largely changed by accepting an excess electron: the binding site of the hydrogen bond of MeOH is changed from the nonbonding to the π* orbitals in carbonyl CdO. This structural change occurred as a unimolecule within the Bp -‚‚‚MeOH complex. With the change of the solvation structures, the absorption spectra of Bp -were gradually blue-shifted as a function of reaction time. The solvation mechanism was discussed on the basis of the theoretical results.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Dynamic Spectral Shift of Benzophenone Radical Anion Caused by the Solvent Molecule Reorientation. Semiempirical PM3-MO and Classical Trajectory Studies

Tachikawa

1996

J. Phys. Chem.

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“…Use of a high concentration of a solute (say, >0.15 mol dm –3 ) in alcoholic solution ensures that the solute captures the dry or quasi-localized electron before the solvation of the electron is complete (Scheme ) and hence does not put any limitation on the reaction time of the electron with the solute, so that electron solvation process cannot compete with the process of formation of fluorenone anion. It has been shown earlier that less than 5% of the total number of electrons remains unreactive in the presence of 0.05 M of an aromatic solute (say benzophenone) at room temperature, and the concentration of solvated electron decreases exponentially as the solute concentration is increased . It has also been shown that the ratio of the yield of solvated electron at the solute concentration of 0.15 mol dm –3 to that in the absence of the solute would be expected to be (0.05) 3 or 1.25 × 10 –4 …”

Section: Resultsmentioning

confidence: 99%

“…Subsequently, Huddleston and Miller studied the spectral relaxation of benzophenone anion in methanol and ethanol glasses at 4 and 77 K. At 4 K, no spectral shift was observed in ethanol, but a very slow blue-shift in methanol (only 70 nm from 810 to 740 nm within 100 s). , However, at 77 K, a larger blue-shift was observed in either of these alcohols (from 810 to 625 nm within 100 s). Similarities between the spectral shifts observed in the case of benzophenone anion and that of trapped electrons (e – t ) in the same matrices led the authors to rule out a hopping process for e – t .…”

Section: Introductionmentioning

confidence: 99%

“…Works of Marignier and Hickel , inspired Jonah and co-workers to further investigate solvation of benzophone anion in alcohols at room temperature using picosecond pulse radiolysis techniques. This led Jonah to publish an important series of papers from 1992 to 2003 mainly about benzophenone anion solvation and its comparison with that of electron as well as dipoles. ,,,,− For alcohols such as 1-propanol and 2-propanol, it was necessary to lower the temperature in the range 263–223 K to slow down the process, which was too rapid at room temperature to be measured . For larger alcohols, such as 1-butanol, 1-decanol, or 1-octanol, measurements could be achieved at room temperature. , Their works proposed that the spectral shift obey unambiguously to a continuous process and that the rotational motion of the C–OH bond influencing it.…”

Section: Introductionmentioning

confidence: 99%

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Picosecond Pulse Radiolysis Study of Dynamics of Solvation of Electron and Fluorenone Anion in Primary Alcohols

2013

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We have studied the dynamics of solvation of electron injected directly into primary alcohols as well as that of fluorenone anion using pulse radiolysis technique with the time resolution of about 15 ps. Unlike in the previous reports, we observe nonexponential dynamics of both electron and anion solvation. While the ultrafast component, τ1 (<15 ps) representing the inertial time scale of the dynamics is faster than the time resolution of the spectrometer, the slower component, τ2, has been assigned to the translational motion leading to structural changes of the hydrogen bonding network of the solvent in the inner solvation cell or alcohol cluster. τ2 agrees well with the electron solvation times reported by the earlier authors. τ3 is associated with the restructuring of the hydrogen bond network structure of the solvent in the region outside the solvation cell. Nonexponential solvation dynamics of the fluorenone anion has been described well by a two-component process. The most important observation in this work is that the lifetime of the shorter component, τ1, determined in four alcoholic solvents, is much longer than the electron solvation time in the corresponding solvents determined in this work or anion solvation time reported earlier. The lifetime of this component is nearly comparable with the average dipolar solvation time but shorter than the longitudinal relaxation time of the solvent. In the case of anion, τ1 has been assigned to the restructuring of the first solvation shell by breakage of solvent hydrogen bonds of the fluorenone molecule and formation of hydrogen bonds with the anion. In this case, too, the longer component, τ2, with the lifetime of a few nanoseconds, has been assigned to reorganization of hydrogen bonds in the solvent hydrogen bond network structure.

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Remote Sensitized Photoisomerization via Through‐Bond Triplet–Triplet Energy Transfer Mediated by a Salt Bridge in a Supramolecular Dyad

Han

Wei

et al. 2010

ChemPhysChem

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A supramolecular dyad, BP-(amidinium-carboxylate)-NBD is constructed, in which benzophenone (BP) and norbornadiene (NBD) are connected via an amidinium-carboxylate salt bridge. The photophysical and photochemical properties of the assembled BP-(amidinium-carboxylate)-NBD dyad are examined. The phosphorescence of the BP chromophore is efficiently quenched by the NBD group in BP-(amidinium-carboxylate)-NBD via the salt bridge. Time-resolved spectroscopy measurements indicate that the lifetime of the BP triplet state in BP-(amidinium-carboxylate)-NBD is shortened due to the quenching by the NBD group. Selective excitation of the BP chromophore results in isomerization of the NBD group to quadricyclane (QC). All of these observations suggest that the triplet-triplet energy transfer occurs efficiently in the BP-(amidinium-carboxylate)-NBD salt bridge system. The triplet-triplet energy transfer process proceeds with efficiencies of approximately 0.87, 0.98 and the rate constants 1.8x10(3) s(-1), and 1.3x10(7) s(-1) at 77 K and room temperature, respectively. The mechanism for the triplet-triplet energy transfer is proposed to proceed via a "through-bond" electron exchange process, and the non-covalent bonds amidinium-carboxylate salt bridge can mediate the triplet-triplet energy transfer process effectively for photochemical conversion.

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Spectral relaxation of the benzophenone negative ion in alcohol glasses: Evidence for solvent reorientation

Cited by 10 publications

References 40 publications

Dynamic Spectral Shift of Benzophenone Radical Anion Caused by the Solvent Molecule Reorientation. Semiempirical PM3-MO and Classical Trajectory Studies

Dynamic Spectral Shift of Benzophenone Radical Anion Caused by the Solvent Molecule Reorientation. Semiempirical PM3-MO and Classical Trajectory Studies

Picosecond Pulse Radiolysis Study of Dynamics of Solvation of Electron and Fluorenone Anion in Primary Alcohols

Remote Sensitized Photoisomerization via Through‐Bond Triplet–Triplet Energy Transfer Mediated by a Salt Bridge in a Supramolecular Dyad

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