Time-Resolved Photoacoustics Determination of Intersystem Crossing and Singlet Oxygen Photosensitization Quantum Yields for 4,5',8-Trimethylpsoralen

Losi, Aba; Bedotti, Roberta; Viappiani, Cristiano

doi:10.1021/j100043a069

Cited by 18 publications

(6 citation statements)

References 13 publications

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“…Since the energy of singlet molecular oxygen is known, it is possible to determine the singlet oxygen yield from simple calorimetric calculations. 5,16,138 A comparison between the precision in the obtained parameters using the maximum amplitude and deconvolution methods showed that, when the maximum amplitude method is applicable, it yields equivalent but more precise results. 132 Using similar methodologies, the triplet yield and the singlet oxygen quantum yield was also determined for tetraphenylporphyrin and its Zn and Cu complexes, 139 as well as for halogenated chlorins.…”

Section: Triplet States and Singlet Oxygen: Volume Changes And Quantu...mentioning

confidence: 99%

Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Gensch

Viappiani

2003

Photochem Photobiol Sci

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Photothermal methods are currently being employed in a variety of research areas, ranging from materials science to environmental monitoring. Despite the common term which they are collected under, the implementations of these techniques are as diverse as the fields of application. In this review, we concentrate on the recent applications of time-resolved methods in photochemistry and photobiology.

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Section: Triplet States and Singlet Oxygen: Volume Changes And Quantu...mentioning

confidence: 99%

Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Gensch

Viappiani

2003

Photochem Photobiol Sci

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“…8 Measurements of the corresponding quantum yields F D revealed moderate to sizeable values depending on the system under consideration. 7,[9][10][11] Furthermore, [2 + 2]photocycloadditions to fatty acids, electron transfer reactions, and fragmentation processes have been reported. 3,7 Commonly, photocycloadditions of psoralens to DNA bases are accounted as the key to understanding the mechanisms underlying the PUVA treatment.…”

Section: Introductionmentioning

confidence: 99%

Intersystem crossing driven by vibronic spin–orbit coupling: a case study on psoralen

Tatchen

Gilka

Marian

2007

Phys. Chem. Chem. Phys.

145

158

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For 7H-furo[3,2-g][1]benzopyran-7-one (psoralen), intersystem crossing (ISC) rate constants have been computed. Employing the Fermi golden rule, the harmonic approximation, and a pure-spin Born-Oppenheimer basis, both direct and vibronic spin-orbit (SO) coupling has been taken into account. Necessary data on electronic excitation energies and potential energy hypersurfaces originate from correlated all-electron calculations applying (time-dependent) density functional theory and the density functional theory/multireference configuration interaction approach. SO coupling has been treated by means of the one-center mean-field approximation. Vibronic SO couplings have been evaluated via numerical differentiation of SO matrix elements. Accounting only for direct SO coupling, rate constants of the order of k(ISC) approximately 10(10) s(-1) result for S2(n --> pi*) --> T1(pi --> pi*) ISC, whereas the rates of the channels S1 (pi --> pi*) --> {1,2 3} (pi --> pi*) do not exceed k(ISC) approximately 10(5) s(-1). Including vibronic SO coupling, rate constants of k(ISC) approximately 3 x 10(8) s(-1) are obtained for the S1 (pi --> pi*) --> T1 (pi --> pi*) ISC. The radiationless transition from the S1(pi --> pi*) state to the nearly degenerate T3(pi --> pi*) state has been estimated to be slightly less efficient (k(ISC) approximately 10(7) s(-1)). Based on our computed rates of ISC and excited state solvent shifts, we conclude that the experimentally observed appreciable triplet quantum yields of psoralen in polar protic media are primarily due to S1(pi --> pi*) --> T (pi --> pi*) channels. For heteroaromatic systems, (pi --> pi*)/(pi --> pi*) ISC driven by vibronic SO coupling is expected to be a common triplet state population mechanism.

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“…Our measurement of HMT emission quantum yield is comparable to that of its parent compound, trimethylpsoralen (TMP) whose values in ethanol and H,O/ethanol (96%) are 0.044 and 0.087, respectively, based on 355 nm excitation (20.21). Although all of our measurements were on nondeoxygenated solutions, neither the emission of quinine sulfate nor TMP appears to be very sensitive to deoxygenation (16,21), and our value for the emission quantum yield of HMT appears to be reasonable for purposes of estimating the two-photon absorption coefficient.…”

Section: $The Results Also Includes a Correction For Differences In Rementioning

confidence: 87%

Two‐Photon Excitation of 4'‐Hydroxymethyl‐4,5',8‐Trimethylpsoralen

Stanley

Lin

et al. 1997

Photochem & Photobiology

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Psoralens are a class of pharmaceutical agents commonly used to treat several cutaneous disorders. When irradiated with a mode-locked titanium: sapphire (Ti:sapphire) laser tuned to 730 nm, an aqueous solution of 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) emits blue light. The emission spectrum is centered at 452 nm and is identical to that obtained by one-photon excitation with UVA excitation, and its magnitude depends quadratically on the intensity of laser excitation. These results suggest that two-photon excitation occurs to a potentially photochemically active state. To estimate the two-photon absorption cross section, it was first necessary to measure the emission quantum yield of HMT using 365 nm excitation at room temperature that resulted in a value of 0.045 +/- 0.007. The two-photon absorption cross section of HMT at 730 nm is therefore estimated to be 20 x 10(-50) cm4 s (20 Göppert-Mayer). The excited-state photophysics and photochemistry of psoralens suggest potential applications to cutaneous phototherapy in diseases such as psoriasis and dystrophic epidermolysis bullosa.

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Time-Resolved Photoacoustics Determination of Intersystem Crossing and Singlet Oxygen Photosensitization Quantum Yields for 4,5',8-Trimethylpsoralen

Cited by 18 publications

References 13 publications

Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Time-resolved photothermal methods: accessing time-resolved thermodynamics of photoinduced processes in chemistry and biology

Intersystem crossing driven by vibronic spin–orbit coupling: a case study on psoralen

Two‐Photon Excitation of 4'‐Hydroxymethyl‐4,5',8‐Trimethylpsoralen

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