Porphycene (PC), a structural isomer of porphine, is a promising photosensitizer for photodynamic therapy. Its excited states can be quenched by molecular oxygen, generating singlet O2. The electronic structures of PC and of the PC⋯O2 complex were investigated using complete active space perturbation theory. It is shown that singlet oxygen generation involves 12 electronic states of the complex, with singlet, triplet, and quintet multiplicities. Two scenarios for singlet-O2 yield are analyzed: (I) quenching of triplet states of PC and (II) quenching of singlet states of PC. In the first scenario, which is favored under low O2 concentration, singlet-O2 yield is limited by the relatively low triplet quantum yield of PC. We discuss how the singlet-O2 yield would be busted if conditions for occurrence of the second scenario could be achieved.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1063/1.4818490 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Photocatalytic Cascade Reaction Driven by Directed Charge Transfer over V -Zn Cd S/GO for Controllable Benzyl Oxidation.
Adv Sci (Weinh)
July 2023
Chemistry Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an, 710127, P. R. China.
Photocatalysis is an important technique for synthetic transformations. However, little attention has been paid to light-driven synergistic redox reactions for directed synthesis. Herein, the authors report tunable oxidation of benzyl to phenylcarbinol with the modest yield (47%) in 5 h via singlet oxygen ( O ) and proton-coupled electron transfer (PCET) over the photocatalyst Zn Cd S (ZCS)/graphene oxide (GO) under exceptionally mild conditions.
View Article and Find Full Text PDFPhotoisomerization of di-nuclear rhenium(i) bpe-based compounds.
Photochem Photobiol Sci
October 2018
Federal University of ABC - UFABC, Av. dos Estados 5001, Santo Andre, SP 09210-170, Brazil.
Di-nuclear [{(NN)(CO)3Re}2(trans-bpe)](PF6)2 complexes, NN = 4,7-diphenyl-1,10-phenanthroline (ph2phen) or 4,7-dichloro-1,10-phenanthroline (Cl2phen) and trans-bpe = trans-1,2-bis(4-pyridyl)ethylene, were synthesized and characterized by 1H NMR and UV-visible spectroscopy. Irradiation of acetonitrile solutions led to 1H NMR and UV-visible spectral changes ascribed to trans-to-cis photoisomerization processes showing that the presence of another Re(i)-moiety does not preclude the photoisomerization process. Quantum yields for the di-nuclear isomerization of [{(ph2phen)(CO)3Re}2(trans-bpe)]2+ were higher than those for the corresponding mono-nuclear compound process.
View Article and Find Full Text PDFMechanistic and Kinetic Study of Singlet O2 Oxidation of Methionine by On-Line Electrospray Ionization Mass Spectrometry.
J Am Soc Mass Spectrom
January 2016
Department of Chemistry and Biochemistry, Queens College and the Graduate Center of the City University of New York, Queens, NY, 11367, USA.
We report a reaction apparatus developed to monitor singlet oxygen ((1)O2) reactions in solution using on-line ESI mass spectrometry and spectroscopy measurements. (1)O2 was generated in the gas phase by the reaction of H2O2 with Cl2, detected by its emission at 1270 nm, and bubbled into aqueous solution continuously. (1)O2 concentrations in solution were linearly related to the emission intensities of airborne (1)O2, and their absolute scales were established based on a calibration using 9,10-anthracene dipropionate dianion as an (1)O2 trapping agent.
View Article and Find Full Text PDFElectronic states of porphycene-O2 complex and photoinduced singlet O2 production.
J Chem Phys
August 2013
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim, Germany.
Porphycene (PC), a structural isomer of porphine, is a promising photosensitizer for photodynamic therapy. Its excited states can be quenched by molecular oxygen, generating singlet O2. The electronic structures of PC and of the PC⋯O2 complex were investigated using complete active space perturbation theory.
View Article and Find Full Text PDFAlpha-methylstilbene and the duality of mechanism in the quenching of stilbene triplets by molecular oxygen.
Photochem Photobiol
June 2006
Department of Chemistry and Biochemistry, The Florida State University, Tallahassee, FL 32306-4390, USA.
Spin-exchange quenching of alpha-methylstilbene triplets by molecular oxygen and by the free radical di-tert-butyl nitroxide is shown to favor the cis isomer more than does natural decay. The effect of the two quenching events is an identical 7% decrease in the fraction of perpendicular triplets that decay to the trans isomer. The conclusion that relaxed stilbene triplets reside in a shallow minimum corresponding to a geometry in which the two benzyl moieties are orthogonal was based on the observation that their quenching by O2 does not alter the trans/cis photostationary ratio.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!