Properties of excited tetrakis(sulfonatophenyl)porphyrin in aqueous solutions. Photoredox reactions with quenchers

Nahor, Gad S.; Rabani, Joseph; Grieser, Franz

doi:10.1021/j150606a018

Cited by 38 publications

(29 citation statements)

References 2 publications

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“…5). It is worth to mention that for the particular case of non-protonated TPPS in the absence of micelles, a great similarity is observed with previous DA results reported in the literature [31]. The observed variation of optical absorption of the solution is caused by the difference between absorption cross-sections assigned to the singlet-singlet (r 01 (k)) and the triplet-triplet (r 34 (k)) transitions.…”

Section: Resultssupporting

confidence: 85%

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Excited-state absorption of meso-tetrasulfonatophenyl porphyrin: Effects of pH and micelles

et al. 2015

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Section: Resultssupporting

confidence: 85%

“…The observed variation of optical absorption of the solution is caused by the difference between absorption cross-sections assigned to the singlet-singlet (r 01 (k)) and the triplet-triplet (r 34 (k)) transitions. The differential optical absorption can be calculated from [28,31]:…”

Section: Resultsmentioning

confidence: 99%

Excited-state absorption of meso-tetrasulfonatophenyl porphyrin: Effects of pH and micelles

et al. 2015

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“…The molar absorption coefficient of 3 TSPP 4-, and of the TSPP 3-• radical at 460 nm, were T ) 65 000 M -1 cm -1 and R ) 21 000 M -1 cm -1 , respectively. 21 The transient absorbance remaining after 4 µs upon quenching of 3 TSPP 4- (Figure 1), due to the absorption by TSPP 3-• , ∆ R A, and measured at 6 µs, was used for the determination of Φ R .…”

Section: Methodsmentioning

confidence: 99%

Photoinduced Electron Transfer from Tetrasulfonated Porphyrin to Benzoquinone Revisited. The Structural Volume-Normalized Entropy Change Correlates with Marcus Reorganization Energy

et al. 2006

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Time-resolved laser-induced optoacoustic spectroscopy was used for the determination of the enthalpy, DeltaTH, and structural volume changes, DeltaTV, concomitant with triplet state formation upon excitation of meso-tetrakis(4-sulfonatophenyl)porphyrin, TSPP(4-), as well as with the triplet state electron-transfer (ET) quenching by benzoquinone, BQ (DeltaRH and DeltaRV). The values of DeltaTH and DeltaTV for (3)TSPP(4-) formation in the presence of different cations (Li+, Na+, K+, NH4+, and Cs+) correlated with each other and afforded a value of DeltaTG = 140 +/- 20 kJ mol(-1), equal to the value of E+ at 77 K, but much larger than the DeltaTH values in solution at room temperature, due to the large entropic factor in solution. The influence of the cations on DeltaTH and DeltaTV (a contraction ranging from 5.4 to 3.8 cm3 mol(-1)) is attributed to changing chromophore-water interactions in the ground and triplet states. Upon quenching of 3TSPP(4-) by BQ, the quantum yield of free radical formation, PhiR = 0.66 +/- 0.04, is the same in the solutions of the five cations. The values of DeltaRH and DeltaRV are small and have a large error. The energy level of the free radicals formed is thus very similar to that of 3TSPP(4-). TDeltaRS and X = TDeltaRS/DeltaRV, i.e., the structural volume change-normalized entropy change for free radicals formation, were derived using average values of DeltaRH and DeltaRV together with the calculated DeltaRG degrees . The measured Marcus reorganization energy, lambda, and X fall into the lambda vs X linear dependence we previously found for the radical formation upon ET quenching of triplet flavins (3FMN and 3FAD) by amines and amino acids. Thus, X = TDeltaRS/DeltaRV in aqueous solutions is a property of the particular donor-acceptor pair linearly correlated to the corresponding Marcus reorganization energy. The value of X is much larger than the predicted value applying the electrostriction concepts in view of the noncontinuum nature of the aqueous solutions.

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“…1 O 2 overall rate constants (k r + k q ) for compounds 2-5 were measured by flash photolysis by using a system already described in detail. 44,45 …”

Section: Discussionmentioning

confidence: 99%

“…A rough estimation of (k r + k q ) = 2.1 x 10 8 M -1 s -1 was obtained in D 2 O at pH = 7.5 using tetrasodium tetrakis(sulfonatophenyl) porphyrin as a sensitizer of 1 O 2 . 44 This rate constant could not be determined very accurately by this photopphysical method because the screening effect of carminic acid on the absorbance of the photosensitizer restricted the practical range of substrate concentration. Keeping in mind this problem, we may consider that the values obtained by both methods are in reasonably good agreement.…”

Section: Limits Of the Methodsmentioning

confidence: 99%

Determination of physical (kq) and chemical (kr) rate constants for singlet oxygen quenching using the thermolysis of a naphthalenic endoperoxide in H2O and D2O

Pierlot¹,

Nardello²,

Schmidt³

et al. 2007

Arkivoc

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The first one (carminic acid) is a foodstuff coloring agent (C.I. Natural Red 4). The four other ones (methyl gallate, caffeic acid, trimethylhydroquinone, trolox) are well-known phenolic antioxidants. All of them exhibit high overall rate constants (10 7 M -1 s -1 < (k r + k q ) < 10 9 M -1 s -1 ) and varying range of chemical quenching (0.1 < k r /(k r + k q ) ≤ 1). The limits of the method are also discussed in detail.

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Properties of excited tetrakis(sulfonatophenyl)porphyrin in aqueous solutions. Photoredox reactions with quenchers

Cited by 38 publications

References 2 publications

Excited-state absorption of meso-tetrasulfonatophenyl porphyrin: Effects of pH and micelles

Excited-state absorption of meso-tetrasulfonatophenyl porphyrin: Effects of pH and micelles

Photoinduced Electron Transfer from Tetrasulfonated Porphyrin to Benzoquinone Revisited. The Structural Volume-Normalized Entropy Change Correlates with Marcus Reorganization Energy

Determination of physical (kq) and chemical (kr) rate constants for singlet oxygen quenching using the thermolysis of a naphthalenic endoperoxide in H2O and D2O

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