Intermediates in the Room Temperature Flash Photolysis and Low Temperature Photolysis of Purine Solutions

Arce, Rafael; Jimenez, L. A.; Rivera, Víctor Anthony García; Torres, Carlos

doi:10.1111/j.1751-1097.1980.tb03991.x

Cited by 16 publications

(10 citation statements)

References 23 publications

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“…Assuming equal concentrations of 7MAde and crocetin triplets, a minimum 7MAde triplet concentration of 8 X lo-' M was estimated, 8 times higher than the triplet concentration observed in AdeH-irradiated solutions and a tenth of the aqueous electron concentration. A triplet-triplet absorption maximum at 405 nm with a lifetime of 55 ps has been reported for 2-aminopurine (Szabo et al, 1975) and an absorption band in the wavelength region of 340-470 nm was assigned to the purine free-base triplet state (Arce et al, 1980). If the 7MAde triplet state is an intermediate state in its photoionization mechanism, the absence of the 310-nm maximum in an 02-saturated solution could imply that this absorption is due to a transient species having a triplet precursor such as a 7MAde radical cation.…”

Section: -Methyladenine and 9-methyladeninementioning

confidence: 90%

CHARACTERIZATION OF THE TRANSIENT SPECIES IN THE 266‐nm LASER PHOTOLYSIS OF ADENINE AND ITS DERIVATIVES

Arce

1987

Photochem & Photobiology

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Abstract. Transient absorption spectra produced by 266‐nm ns laser flash photolysis of aqueous solutions of adenine, 2′‐deoxyadenosine, 2′‐deoxyadenosine‐5′‐phosphate, adenosine‐5′‐phosphate, 2′‐deoxyadenylyl‐(3′‐5′)‐2‐deoxyadenosine, 7‐methyladenine and 9‐methyladenine have been measured under different pH conditions. The transients observed after excitation consisted mainly of the hydrated electron, the radical cation, the radical anion and/or neutral radicals resulting from its protonation, and a minor contribution from the excited triplet state. The photoionization occurs mainly through an excited singlet state. For adenine, the cation and anion radical absorption spectra were determined using laser and pulse radiolysis techniques. The triplet state presence was established through sensitization experiments. The hydrated electron decays following a pseudo‐first‐order reaction with the neutral base.

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Section: -Methyladenine and 9-methyladeninementioning

confidence: 90%

CHARACTERIZATION OF THE TRANSIENT SPECIES IN THE 266‐nm LASER PHOTOLYSIS OF ADENINE AND ITS DERIVATIVES

Arce

1987

Photochem & Photobiology

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“…It has been proposed that the triplet state absorbs the second photon, but it has been difficult to detect this state in transient spectroscopy experiments. A triplet-triplet absorption for various Ade (25,28) and Gua (29,35) derivatives has not been detected upon their direct excitation with microsecond or nanosecond flash photolysis. But triplet absorption signals have been observed in the 380-470 nm wavelength region in experiments where the triplets were produced by photosensitization (65)(66)(67).…”

Section: Mechanism Of Pi For the Dna And Rna Bases At 266 Nm Nanosecomentioning

confidence: 94%

“…Previous studies have suggested that monophotonic PI of DNA and RNA bases could occur at ca 250 nm low-intensity irradiations (15,16,18,(35)(36)(37)(38). But the potential existence of a monophotonic pathway using either 248 or 266 nm laser excitation has received much less attention despite its great relevance to DNA photobiology.…”

Section: Pi Of the Dna And Rna Bases And Derivatives Through A Combinmentioning

confidence: 99%

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

Crespo‐Hernández

Arce

2002

Photochem Photobiol

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The 266 nm nanosecond laser photolysis of various purine and pyrimidine derivatives results in their photoionization (PI) as one of the primary photochemical pathways. Electron photoejection occurs through a combination of one- and two-photon mechanisms. The PI values depend on the substituents attached to the chromophore of the base. The net PI of the purine bases at 266 nm are of the same order of magnitude (10(-2)) as those of the pyrimidine bases under similar experimental conditions. The monophotonic component is approximately one-third of the net PI yield of the bases. A nonrelaxed singlet excited state intermediate is tentatively proposed for this pathway. It is proposed that this state is significantly stabilized by water solvation, transforming it into a charge transfer to solvent state from which the hydrated electron evolves.

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“…As is known, MnC1, (34,35), O2 (27,35) and Xe (27.36) have been described as effective quenchers of triplet states.…”

Section: -Chloropurine 6-merhoxypurine 6-aminopurine (Adenine)mentioning

confidence: 97%

A Photophysical Study of Purines and Theophylline by Using Laser‐Induced Optoacoustic Spectroscopy

Murgida

Bilmes

Erra‐Balsells

1996

Photochem & Photobiology

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The photophysics of purinic compounds (purine, 6-methylpurine, 6-aminopurine [adenine], 6-chloropurine, 6-methoxypurine) and theophylline in acetonitrile solution were studied by pulsed laser-induced optoacoustic spectroscopy (LIOAS) exciting at 266 nm. The effect of O2, Xe and MnCl2 on the photophysical behavior of these compounds was studied; as well, the formation quantum yield of purine and 6-methylpurine triplet states were determined, with phi T = 0.88 +/- 0.03 for both compounds. Multiphotonic and depletion processes were observed at high laser fluences. In order to explain this behavior, theoretical UV-visible absorption electronic spectra from both the S0 and S1 state have been calculated for purines and theophylline by using the semiempirical PM3 and ZINDO/S methods.

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Intermediates in the Room Temperature Flash Photolysis and Low Temperature Photolysis of Purine Solutions

Cited by 16 publications

References 23 publications

CHARACTERIZATION OF THE TRANSIENT SPECIES IN THE 266‐nm LASER PHOTOLYSIS OF ADENINE AND ITS DERIVATIVES

CHARACTERIZATION OF THE TRANSIENT SPECIES IN THE 266‐nm LASER PHOTOLYSIS OF ADENINE AND ITS DERIVATIVES

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

A Photophysical Study of Purines and Theophylline by Using Laser‐Induced Optoacoustic Spectroscopy

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