Influence of Intense Magnetic Fields  on the Rate of Relaxation of [Cr(phen)3+]

ANGEL ANZANI; PABLO F. GARCIA; GERARDO ARGÜELLO; MAXI A. BURGOS PACI

Carlos Paz

Encuentro; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología (ELAFOT); 2017

P { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 10); widows: 2; orphans: 2; }P.western { }P.cjk { }P.ctl { }A:link { color: rgb(5, 99, 193); }Magneticfields can alter theP { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 10); widows: 2; orphans: 2; }P.western { }P.cjk { }P.ctl { }A:link { color: rgb(5, 99, 193); } speed, yield or product distribution of chemicalreactions [1]. Although significant differences have been reported inthe mechanisms by which the magnetic field disturbs the reactionrates of coordination complexes and the mechanisms that apply toreactions between radicals or excited states of organic molecules,the measurement and analysis of the effect of magnetic fields haveprovided information on the reactivity, structure and movement of thespecies subjected to its effects. Intense magnetic fields (B >5T) can modify the photoreactivity of transition metal complexes,generating changes in emission spectra, relaxation of excited state,quantum reaction yields and quenching processes [2] .Inthis work we present the results obtained on the effects of intensemagnetic field (B≈ 0-10 T) on the kinetics of deactivation of Cr(III) complexes with polypyridine ligands. The magnetic field in thereaction cell is generated with a home made system consisting in ahigh voltage capacitor, an electric coil and triggering electronics.The magnetic pulse is coupled to a Nd-YAG laser (Brillant-B, Quantel)operating at 355 nm. Lifetimes (0=1/k0nr)of the excited states of the complexes (2T/2E)[Cr(phen)3]3+were measured in aerated solutions at room temperature (phosphatebuffer pH = 8.0; NaCl 0.1 M) in the absence and presence of appliedmagnetic field (B = 2, 4, 6 and 8 T) obtaining the lifetimes shown inTable 1 and Figure 1.P { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 10); widows: 2; orphans: 2; }P.western { font-family: "Calibri",serif; font-size: 12pt; }P.cjk { font-family: "WenQuanYi Zen Hei Sharp"; font-size: 12pt; }P.ctl { font-family: "Calibri"; font-size: 12pt; }A:link { color: rgb(5, 99, 193); }References:[1]U.Steiner, P. Ulrich, Chem. Rev., 89 (1989) 51.[2]G.A. Argüello, G. Ferraudi, J. Phys. Chem., 92 (1988) 1846.