Time-Resolved Absorption Spectrum of Singlet Oxygen in Solution

Weldon, Dean; Ogilby, Peter R.

doi:10.1021/ja9833366

Cited by 29 publications

(62 citation statements)

References 22 publications

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“…Also shown in Fig. 2 are (1) the kp value obtained in a solution-phase b + a emission experiment (1 2), and (2) e values obtained in solution-phase a + b absorption experiments (19). With respect to Minaev's predictions regarding the ratio k ; -x l p , the respective data sets indeed appear to respond similarly to changes in the solventlperturber on the scale of the double-logarithmic plot.…”

Section: -7)mentioning

confidence: 70%

“…0.51 X 10' s-I) (19) and an independent b + a emission experiment (2.1 X lo3 s -I ) (14) is remarkably good. However, this issue requires additional study because the latter value (14) was obtained using an overall O,(b'X,+) lifetime in CS2 that differs significantly from values independently obtained (vide infra, Table 1).…”

Section: -7)mentioning

confidence: 83%

“…This paucity of data is a consequence, in part, of the comparatively short O,(blX,+) lifetime and of the need for more information on the effect of solvent on 02(b1X,+) yields (vide infra). However, because the 02(a1Ag) spectrum can now be detected in absorption experiments (19), solvent effects on the a + b radiative transition can be quantified. Nevertheless, it is still desirable to have values of k y , certainly if one wants to compare b-a radiative data with data obtained from the a-X transition, for which absorption coefficients are difficult to obtain.…”

Section: -7)mentioning

confidence: 99%

“…Therefore, although Minaev's thesis of intensity stealing appears to be correct generally, it also appears that some modification in the model is required to account for subtle changes in the k ; -x l e ratio. (19). For the solution-phase data, R was obtained using the relation R = V,(n2 -I)/(n2 + 2).…”

Section: -7)mentioning

confidence: 99%

“…hereafter denoted b + a, and the O2(b1B,+>-O2(X3B,-) phosphorescent transition at -760 nm (1618), hereafter denoted b + X. We recently reported (19) that the b-a transition can also be detected in a time-resolved absorption experiment (a + b) under identical conditions used to monitor singlet oxygen emission (1 cm path length, air-saturated solutions at l atm). The absorption experiment not only provides a new method by which 02(a1A,) can be monitored but also makes it possible to obtain information from systems where the b + a and a + X emission experiments are limited.…”

Section: Introductionmentioning

confidence: 99%

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Singlet Sigma: The “Other” Singlet Oxygen in Solution

Weldon

Poulsen

Mikkelsen

et al. 1999

Photochem & Photobiology

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The lowest excited electronic state of molecular oxygen, 02(a1Ag), is often called simply singlet oxygen. This singlet delta state is an acknowledged and well-studied intermediate in many solution-phase photosystems. However, the second excited electronic state of oxygen, O,(b'X,+), is also a singlet. It has recently become possible to monitor this singlet sigma state in solution, which, in combination with studies of the singlet delta state, contributes to a better understanding of a variety of general problems in chemistry.

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Section: -7)mentioning

confidence: 70%

Section: -7)mentioning

confidence: 83%

Section: -7)mentioning

confidence: 99%

Section: -7)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Singlet Sigma: The “Other” Singlet Oxygen in Solution

Weldon

Poulsen

Mikkelsen

et al. 1999

Photochem & Photobiology

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Theoretical study of the hydrogen bond interaction between methylene blue and water and possible role on energy transfer for photodynamics

Quintão

Coutinho

Canuto

2002

Int J of Quantum Chemistry

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Density-functional theory calculations using B3LYP/6-31+G(d) are performed on the hydrogen bond interaction between methylene blue (MB + ) and water to analyze the structure, binding energy and change in spectroscopic properties. The vibrational frequency observed in the region of 1200 cm −1 is found to present the larger shift (+10 cm −1 ), and corresponds to the asymmetric in-plane twist mode of C-C bond of the central ring. The binding energy between MB + and water is calculated for three different isomers giving values varying between 3.1 and 5.1 kcal/mol, after correcting for basis-set superposition error. The binding energy is also calculated using Hartree-Fock and other density-functionals, such as B3P86/6-31+G(d) and B3PW91/6-31+G(d). In the most stable isomer considered, the water plays the role of the proton acceptor and the oxygen atom makes multiple hydrogen bonds with MB + . The stability of this isomer is also influenced by other electrostatic interaction between MB + and water. The influence of the complexation on the characteristic visible absorption band of MB + is analyzed using INDO/CIS. Overall, the results indicate that several hydrogen bonds can be formed and some present multiple bonds. However, they all seem to be numerically unimportant for the photochemistry of MB + in water.

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Introduction

Bregnhøj¹

2018

The Electronic Transitions of Molecular Oxygen

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Time-Resolved Absorption Spectrum of Singlet Oxygen in Solution

Cited by 29 publications

References 22 publications

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Theoretical study of the hydrogen bond interaction between methylene blue and water and possible role on energy transfer for photodynamics

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