Relaxation dynamics following transition of solvated electrons

We present condensed-phase first-principles molecular dynamics simulations to elucidate the presence of different electron trapping sites in liquid methanol and their roles in the formation, electronic transitions, and relaxation of solvated electrons (e−met) in methanol. Excess electrons injected into liquid methanol are most likely trapped by methyl groups, but rapidly diffuse to more stable trapping sites with dangling OH bonds. After localization at the sites with one free OH bond (1OH trapping sites), reorientation of other methanol molecules increases the OH coordination number and the trap depth, and ultimately four OH bonds become coordinated with the excess electrons under thermal conditions. The simulation identified four distinct trapping states with different OH coordination numbers. The simulation results also revealed that electronic transitions of e−met are primarily due to charge transfer between electron trapping sites (cavities) formed by OH and methyl groups and that these transitions differ from hydrogenic electronic transitions involving aqueous solvated electrons (e−aq). Such charge transfer also explains the alkyl-chain-length dependence of the photoabsorption peak wavelength and the excited-state lifetime of solvated electrons in primary alcohols.

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Relaxation dynamics in confined glasses

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2000745 ◽

2000 ◽

Vol 10 (PR7) ◽

pp. Pr7-227-Pr7-232 ◽

Cited By ~ 1

Author(s):

B. Jérôme ◽

E. Cecchetto ◽

N. R. de Souza ◽

A. L. Demirel

Keyword(s):

Relaxation Dynamics

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20010109 ◽

2001 ◽

Vol 66 (1) ◽

pp. 109-118 ◽

Cited By ~ 4

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.

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