Photoinduced Intermolecular Electron Transfer in Liquid Solutions

Abstract

Intermolecular photoinduced electron transfer between Rhodamine 3B cation (R3B + ), and dimethylanaline (DMA) is studied in a variety of solvents using pump-probe spectroscopy from ultrashort times (∼100 fs) to long times (∼10 ns). Excitation of R3B + results in the transfer of an electron from DMA and the production of the neutral radical R3B and the DMA + radical cation. Using a very broadband continuum probe, the generation of the R3B neutral radical is observed (430 nm) as well as the ground state bleach (550 nm), an excited state absorption (445 nm), and stimulated emission (620 nm). A good spectrum of the R3B radical is obtained by removing the overlapping excited state absorption. The forward electron transfer is examined by monitoring the time dependence of the stimulated emission. The data are analyzed with a previously presented detailed theory of through-solvent electron transfer for diffusing donors and acceptors, which includes the influences solvent structure and the hydrodynamic effect. Previous studies have shown that the theory works well for times >100 ps. It is found that in a non-hydrogen-bonding solvent (acetonitrile) and in mixtures of hydrogen-bonding solvents, the theory works well down to a few hundred femtoseconds with only one adjustable parameter, the contact electronic coupling matrix element. However, in pure hydrogen-bonding solvents, it is necessary to increase the solvent hard sphere radius used in the radial distribution to theoretically describe the data, which suggest a larger solvent structural unit than a single solvent molecule.

Photoinduced Excited State Electron Transfer at Liquid/Liquid Interfaces

“…[32][33][34][35][36]47 Of particular importance is extending to the L/L interface the idea of using a solvent, such as N,N-dimethylaniline (DMA) as an electron donor. 37,[48][49][50][51] The advantage of this approach is that complications due to ion transfer across the interface and to diffusion are removed.…”

Kinetics of Fe(II) reduction of cis‐halogeno(dodecylamine) bis(ethylenediamine)‐ cobalt(III) complex ion in aqueous solutions

“…Numerous studies have been performed, addressing the dependence of electron transfer on different environments including metalloproteins [8], vitamin B 12 [9], liquids [10,11], micelles [12,13], vesicles [14], and DNA [7]. Electron transfer in restricted geometry system such as micelles, reverse micelles, and vesicles attracts a great deal of interest because of their potential to prolong the lifetime of charge-transfer states, a goal of electrontransfer studies aiming to utilize solar energy [15,16] and as molecular switches [17,18].…”

Kinetics and mechanism of oxidation of GSH by cis-(diaqua)-bis-(ethylenediamine) Cobalt(III) ion

“…Studies on the chemistry of electron transfer reaction of cobalt(III) complexes have received a sustained high level of attention from the scientific community for decades due to their relevance in various redox processes in biological system and act as promising agent for antitumor (Osinsky et al 2003, Osinsky et al 2004), anthelmintic (Behm et al 1993), antiparasitic (Behm et al 1995, Karaman et al 1995, antibiotics (Ghirlanda et al 1998), and antimicrobial activities (Srinivasan et al 2005). Numerous studies have been performed, addressing the dependence of electron transfer on different environments including metalloproteins (Bernauer et al 1999), vitamin B 12 (Wolak et al 2003) , liquids (Burel et al 1999, Saik et al 2004, micelles (Weidemaier et al 1997, Travernier et al 1998, vesicles (Gerasimov et al 1988), and DNA (Srinivasan et al 2005). We report here redox reactions of GSH with Co (III) complex as oxidant and GSH as reductant.…”