Photoredox Reactions of Iodo Iron(III) Complexes Containing Tetradentate Ligands

2001 ◽  
Vol 66 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jozef Šima ◽  
Dáša Lauková ◽  
Vlasta Brezová
Keyword(s):  
Schiff Bases ◽  
Spin Trapping ◽  
Molar Ratio ◽  
Oh Radicals ◽  
Solvated Electrons ◽  
Open Chain ◽  
Tetradentate Ligands ◽  
Visible Irradiation ◽  
Epr Spin Trapping ◽  
Spin Trapping Technique

Photoredox reactions occurring in irradiated methanolic solutions of trans-[FeIII(R,R'-salen)(CH3OH)I], where R,R'-salen2- are N,N'-ethylenebis(R,R'-salicylideneiminato), tetradentate open-chain N2O2-Schiff bases with R,R' = H, 5-Cl, 5-Br, 3,5-di-Br, 3,5-di-(CH3), 3-OCH3, 5-OCH3, have been investigated and their mechanism proposed. The complexes are redox-stable in the dark. Ultraviolet and/or visible irradiation of methanolic solution of the complexes induces photoreduction of Fe(III) to Fe(II). Depending on the composition of the irradiated solutions, •CH2OH radicals or solvated electrons were identified by the EPR spin trapping technique. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde and the molar ratio of Fe(II) and CH2O is close to 2 : 1. The efficiency of the photoredox process is strongly wavelength-dependent and influenced by the peripheral groups R,R' of the tetradentate ligands.

Photodynamic action of C-phycocyanins obtained from marine and fresh water cyanobacterial cultures: A comparative study using EPR spin trapping technique

2006 ◽  
Vol 40 (8) ◽  
pp. 821-825 ◽  
Author(s):  
Bibbin Tom Paul ◽  
Anamika Patel ◽  
Govindan Sadasivam Selvam ◽  
Sandhya Mishra ◽  
Pushpita Kumar Ghosh ◽  
...  
Keyword(s):  
Comparative Study ◽  
Fresh Water ◽  
Spin Trapping ◽  
Photodynamic Action ◽  
Epr Spin Trapping ◽  
Spin Trapping Technique

scholarly journals Fused-Ring Derivatives of Quinoxalines: Spectroscopic Characterization and Photoinduced Processes Investigated by EPR Spin Trapping Technique

Molecules ◽  
2014 ◽  
Vol 19 (8) ◽  
pp. 12078-12098 ◽  
Author(s):  
Zuzana Barbieriková ◽  
Dana Dvoranová ◽  
Maroš Bella ◽  
Viktor Milata ◽  
Adriana Czímerová ◽  
...  
Keyword(s):  
Spectroscopic Characterization ◽  
Spin Trapping ◽  
Fused Ring ◽  
Epr Spin Trapping ◽  
Derivatives Of ◽  
Spin Trapping Technique ◽  
Photoinduced Processes

Photodegradation of 4-chloronitrobenzene in the presence of aqueous titania suspensions in different gas atmospheres

2011 ◽  
Vol 64 (7) ◽  
pp. 1466-1472 ◽  
Author(s):  
Miaomiao Ye ◽  
Tuqiao Zhang ◽  
Zhiwei Zhu ◽  
Yan Zhang ◽  
Yiping Zhang
Keyword(s):  
Spin Trapping ◽  
Photocatalytic Efficiency ◽  
Liquid Chromatography Mass Spectrometry ◽  
Paramagnetic Resonance ◽  
Mineralization Processes ◽  
Degussa P25 ◽  
Epr Spin Trapping ◽  
Electron Paramagnetic ◽  
Nitrate Anions ◽  
Spin Trapping Technique

The photocatalytic degradation of 4-chloronitrobenzene (4-CNB) was carried out using Degussa P25 TiO2 as photocatalyst in three different gas atmospheres: nitrogen, oxygen, and ozone. The total organic carbon (TOC) and inorganic anions including chloride, nitrite, and nitrate anions were measured to monitor the mineralization processes, while the degradation of 4-CNB and the formation of intermediates were followed by liquid chromatography–mass spectrometry (LC/MS). Results showed that the photocatalytic efficiency followed the order of TiO2/UV/N2 < TiO2/UV/O2 < TiO2/UV/O3, which was further proved by evaluating the reaction activities using electron paramagnetic resonance (EPR) spin trapping technique. Chlorine atom, nitro group and hydrogen atom of the benzene ring could be displaced by hydroxyl radical (•OH) leading to the formation of chloride, nitrite (III) anions and a variety of phenols, then the nitrite (III) anions were further oxidized to nitrate (V) anions. 4-Nitrophenol and 5-chloro-2-nitrophenol were identified and quantified in both of the TiO2/UV/N2 and TiO2/UV/O2 processes while no aromatic intermediates were monitored in the process of TiO2/UV/O3.

Evaluation of Methanol Induced Free Radicals in Mice Liver

2017 ◽  
Vol 70 (5) ◽  
pp. 499 ◽  
Author(s):  
Lifang Zhou ◽  
Hongli Zhao ◽  
Tieying Pan ◽  
Adrian Trinchi ◽  
Minbo Lan ◽  
...  
Keyword(s):  
Free Radicals ◽  
Harmful Effect ◽  
Spin Trapping ◽  
Enzyme Assays ◽  
Paramagnetic Resonance ◽  
Mice Liver ◽  
Epr Spin Trapping ◽  
Electron Paramagnetic ◽  
Trapping Agent ◽  
Spin Trapping Technique

Methanol induced oxidative stress (OS) models in mice were successfully established and evaluated by the electron paramagnetic resonance (EPR) spin trapping technique. The capacity for removal of reactive oxygen species (ROS) free radicals by rhubarb and vitamin C (Vc) as candidate materials was also investigated. EPR was employed to determine the free radicals generated from a spin trapping agent, α-phenyl-N-tert-butylnitrone (PBN), that reacted with the ROS. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and the level of malondialdehyde (MDA) were also evaluated by enzyme assays. The results indicated that methanol clearly promoted the generation of ROS free radicals in the liver of mice. The activity of SOD and GSH-PX was reduced significantly, although the level of MDA was increased as a result of the harmful effect of methanol. In addition, rhubarb and Vc exhibited a protective effect on the mice liver under acute OS.

Spin trapping in photochemistry of coordination compounds

1982 ◽  
Vol 60 (12) ◽  
pp. 1565-1573 ◽  
Author(s):  
Detlef Rehorek ◽  
Horst Hennig
Keyword(s):  
Coordination Compounds ◽  
Spin Trap ◽  
Spin Trapping ◽  
Photochemical Reactions ◽  
Paramagnetic Species ◽  
Side Reactions ◽  
Limited Extent ◽  
Solvated Electrons ◽  
Spin Traps ◽  
Spin Trapping Technique

The application of spin-trapping technique to detect short-lived paramagnetic species formed during photochemical reactions of coordination compounds is reviewed. Interference of radical recombinations by scavenging action of spin traps has been pointed out to be important at high spin-trap concentrations only. Due to only a limited extent of side reactions, nitrosodurene and phenyl N-tert-butyl nitrone were found to be excellent spin traps for the study of photoreactions of metal complexes in nonpolar solutions, whereas 5,5-dimethyl pyrroline-1-oxide is recommended for aqueous solutions. Using these spin traps, both organic and inorganic radicals, e.g. H, Cl, N3, CN, OH, O2−, as well as solvated electrons and metal-centered free radicals have been detected during the photolysis of coordination compounds. The detection of singlet oxygen by reaction with 2,2,6,6-tetramethyl piperidine is briefly discussed.

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