Ultraviolet photoionization of the photosensitizers khellin and visnagin in aqueous solution and in micelles: one-photon ionization is a minor process

Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology
Sameh R El-Gogary, Gottfried Grabner

Abstract

One-photon ionization, leading to formation of hydrated electrons and radical cations, has been proposed as a possible mechanism of action of some sensitizers in photobiology. In this contribution, we have investigated this proposal for the compounds khellin and visnagin, used in photomedical applications. Nanosecond transient absorption spectroscopy covering a wide range of laser pulse energies was employed to measure the formation of radical cations and hydrated electrons in aqueous solution and in cationic (CTAB) as well as anionic (SDS) micellar solutions. A model allowing for simultaneous one- and two-photon processes and fully accounting for the nonlinearity of the pulse energy dependence was used to simulate the data. The results did not support the hypothesis of a significant role of one-photon ionization, the upper limits of the quantum yields of radical cation formation being phi < 0.01 for visnagin and phi < 0.004 for khellin.

References

Jan 1, 1991·Pharmacology & Therapeutics·J B Hudson, G H Towers
May 1, 1988·The Journal of Investigative Dermatology·P MorliereL Dubertret
Mar 6, 1998·Photochemistry and Photobiology·M L BorgesA L Maçanita
Oct 31, 2001·Journal of Photochemistry and Photobiology. B, Biology·M J Davies, R J Truscott
Apr 22, 2003·Chemical Research in Toxicology·M Consuelo CuquerellaGuido De Guidi
Apr 28, 2004·Chemistry : a European Journal·Chellappan Selvaraju, Perumal Ramamurthy

❮ Previous
Next ❯

Citations

Sep 14, 2010·Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy·Sameh R El-Gogary
Jul 30, 2008·Journal of Photochemistry and Photobiology. B, Biology·Sameh El-GogaryGottfried Köhler
Aug 8, 2007·Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry·Lucia FlamigniBarbara Ventura
Dec 7, 2007·Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry·Krisztina PálGottfried Grabner
Aug 25, 2021·Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology·Namasivayam DhenadhayalanViruthachalam Thiagarajan

❮ Previous
Next ❯

Related Concepts

Related Feeds

Absence Epilepsy

Absence epilepsy is a common seizure disorder in children which can produce chronic psychosocial sequelae. Discover the latest research on absence epilepsies here.