Metal nanoparticle alters adenine induced charge transfer kinetics of vitamin K3 in magnetic field

Abstract In this article, we highlight the alterations in the photoinduced electron transfer (ET) and hydrogen atom transfer (HAT) pathways between an anti-tumor drug vitamin-K3 (MQ) and a nucleobase adenine (ADN) in the presence of gold (Au) and iron (Fe) nanoparticles (NPs). Inside the confined micellar media, with laser flash photolysis corroborated with an external magnetic field (MF), we have detected the transient geminate radicals of MQ and ADN, photo-generated through ET and HAT. We observe that the presence of AuNP on the MQ-ADN complex (AuMQ-ADN) assists HAT by limiting the ET channel, on the other hand, FeNP on the MQ-ADN complex (FeMQ-ADN) mostly favors a facile PET. We hypothesize that through selective interactions of the ADN molecules with AuNP and MQ molecules with FeNP, a preferential HAT and PET process is eased. The enhanced HAT and PET have been confirmed by the escape yields of radical intermediates by time-resolved transient absorption spectroscopy in the presence of MF.

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Triplet state quenching of phenosafranine dye by indolic compounds studied by transient absorption spectroscopy

Photochemical & Photobiological Sciences ◽

10.1039/c4pp00365a ◽

2015 ◽

Vol 14 (2) ◽

pp. 407-413 ◽

Cited By ~ 3

Author(s):

Martín F. Broglia ◽

Carlos M. Previtali ◽

Sonia G. Bertolotti

Keyword(s):

Triplet State ◽

Absorption Spectroscopy ◽

Transient Absorption ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Laser Flash ◽

Transient Absorption Spectroscopy ◽

Synthetic Dye ◽

Biological Relevance ◽

Indolic Compounds

The interaction of the triplet state of the synthetic dye phenosafranine (3,7-diamino-5-phenylphenazinium chloride) with indolic compounds of biological relevance was investigated in water by means of laser flash photolysis.

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Absorption spectroscopy of singlet CH2 near 11 200 cm1

Canadian Journal of Physics ◽

10.1139/p00-079 ◽

2001 ◽

Vol 79 (2-3) ◽

pp. 347-358 ◽

Cited By ~ 2

Author(s):

K Kobayashi ◽

T J Sears

Keyword(s):

Absorption Spectroscopy ◽

Near Infrared ◽

Transient Absorption ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Energy Levels ◽

Zero Point ◽

Laser Flash ◽

Infrared Region ◽

Transient Absorption Spectroscopy

New spectra of methylene, CH2, in the near infrared region of the singlet band system have been obtained. They were detected by laser transient absorption spectroscopy following excimer laser flash photolysis of ketene, CH2CO, at 308 nm. The new data provide information on the nature and energies of rotational levels in three vibronic states that lie between approximately 11 500 and 13 000 cm1 above the zero point level of the lower, ã1A1, state. Taken together with previous measurements, a fairly complete picture of the vibronic energy levels of CH2 in this region can be built up. There is generally good agreement with the recent computational studies on the singlet states of CH2, but some evidence for discrepancies for levels with K = 3 and higher near the minimum of the [Formula: see text]1B1 potential surface. PACS No.: 33.20Ea

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Intrazeolite photochemistry. IV. Studies of carbonyl photochemistry on the hydrophobic zeolite Silicalite using time-resolved diffuse reflectance techniques

Canadian Journal of Chemistry ◽

10.1139/v86-086 ◽

1986 ◽

Vol 64 (3) ◽

pp. 539-544 ◽

Cited By ~ 29

Author(s):

F. Wilkinson ◽

C. J. Willsher ◽

H. L. Casal ◽

Linda J. Johnston ◽

J. C. Scaiano

Keyword(s):

Diffuse Reflectance ◽

Transient Absorption ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Heterogeneous Systems ◽

Laser Flash ◽

Close Packing ◽

Time Resolved ◽

Adsorption Sites ◽

Norrish Type

Transient absorption and luminescence from aromatic ketone triplets (xanthone, acetophenone, butyrophenone, valerophenone, p-methoxyacetophenone, β-phenyl-p-methoxypropiophenone and benzil) supported on the hydrophobic zeolite Silicalite have been obtained by time-resolved diffuse reflectance laser flash photolysis. These experiments were aimed at establishing the usefulness of this technique for studies of zeolite supported photoreactions. While the transient spectral properties can be used to examine the properties of the supporting media, the decays of the signals frequently follow complex kinetic behaviour. The decays for such heterogeneous systems cannot be easily fit to clean first or second order kinetics and are thought to be a mixture of several first order decays arising from triplets in different inclusion and adsorption sites. Evidence is presented for close-packing of the aromatic substrates and for triplet lifetime enhancement. Although the triplet spectrum of included benzil shows evidence for considerable axial freedom, the results for β-phenylpropiophenones indicate that other types of motion are restricted for included ketones. It is also found that the rate of the Norrish Type II reactions of valerophenone and butyrophenone supported on Silicalite are decreased with respect to the rates in solution.

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Surface photochemistry: Photodegradation study of pyrene adsorbed onto microcrystalline cellulose and silica

International Journal of Photoenergy ◽

10.1155/s1110662x04000261 ◽

2004 ◽

Vol 6 (4) ◽

pp. 205-213 ◽

Cited By ~ 13

Author(s):

A. S. Oliveira ◽

L. F. Vieira Ferreira ◽

J. P. Da Silva ◽

J. C. Moreira

Keyword(s):

Radical Cation ◽

Microcrystalline Cellulose ◽

Ground State ◽

Diffuse Reflectance ◽

Transient Absorption ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Cation Radical ◽

Laser Flash ◽

Time Resolved

Ground-state diffuse reflectance, time resolved laser-induced luminescence, diffuse reflectance laser flash-photolysis transient absorption and chromatographic techniques were used to elucidate the photodegradation processes of pyrene adsorbed onto microcrystalline cellulose and silica. Ground-state diffuse reflectance showed that on both substrates low concentrations display absorption of pyrene monomers. At high concentrations spectral changes attributed to aggregate formation were observed. Laser induced fluorescence showed that pyrene onto microcrystalline cellulose mainly presents fluorescence from monomers, while for silica, excimer-like emission was observed from low surface loadings (≥0.5μmolg−1). Transient absorption and photodegradation studies were performed at concentrations where mainly monomers exist. On silica, pyrene presents transient absorption from its radical cation. On microcrystalline cellulose both radical cation, radical anion and pyrene triplet-triplet absorption were detected. Irradiation followed by chromatographic analysis showed that pyrene decomposes on both substrates. For pyrene on microcrystalline cellulose 1-hydroxypyrene was the main identified photoproduct since in the absence of oxygen further oxidation of 1-hydroxypyrene was very slow. For pyrene on silica photodegradation was very efficient. Almost no 1-hydroxypyrene was detected since in the presence of oxygen it is quickly oxidized to other photooxidation products. On both substrates, pyrene radical cation is the intermediate leading to photoproducts and oxygen it is not involved in its formation.

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Article

Canadian Journal of Chemistry ◽

10.1139/v99-060 ◽

1999 ◽

Vol 77 (5-6) ◽

pp. 787-791

Author(s):

Lorenzo Brancaleon ◽

Darryl Brousmiche ◽

Linda J Johnston

Keyword(s):

Electron Transfer ◽

Photoinduced Electron Transfer ◽

Transient Absorption ◽

Flash Photolysis ◽

Laser Flash Photolysis ◽

Laser Energy ◽

Laser Flash ◽

Transient Absorption Spectroscopy ◽

Direct Excitation ◽

Oxidation Potentials

The electron transfer photochemistry of 2,3-dicyanonaphthalene has been studied by a combination of fluorescence and transient absorption spectroscopy. The singlet excited state has a lifetime of 26 ns in acetonitrile and reacts with aromatic and alkene donors with oxidation potentials less than ~1.8 V with rate constants that are close to the diffusion-controlled limit. Transient absorption measurements demonstrate that the fluorescence quenching leads to efficient formation of free-radical ions. The radical ion yields have been measured for several donors and are compared to those for the more commonly used sensitizer, 1.4-dicyanonaphthalene. In the absence of added donors, direct excitation of 2,3-dicyanonaphthalene provides evidence for photoionization at high laser energy, in addition to triplet formation. The results illustrate the utility of this sensitizer for photoinduced electron transfer reactions.Key words: photoinduced electron transfer, laser flash photolysis, fluorescence, photosensitizers.

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