THE INFLUENCE OF MAGNETIC FIELD INTENCE ON THE RATE OF RELAXATION OF EXCITED STATES OF CR(III) COMPLEXES

ARGUELLO, GERARDO ANIBAL; BURGOS PACI, MAXIMILIANO; ANZANI, ANGEL FEDERICO

Carlos Paz Córdoba

Congreso; XIII ELAFOT 2017; 2017

Magnetic fields can alter the speed, yield or product distribution of chemical reactions [1]. Although significant differences have been reported in the mechanisms by which the magnetic field disturbs the reaction rates of coordination complexes and the mechanisms that apply to reactions between radicals or excited states of organic molecules, the measurement and analysis of the effect of magnetic fields have provided information on the reactivity, structure and movement of the species 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] .In this work we present the results obtained on the effects of intense magnetic field (B≈ 0-10 T) on the kinetics of deactivation of Cr (III) complexes with polypyridine ligands. The magnetic field in the reaction cell is generated with a home made system consisting in a high 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 (phosphate buffer pH = 8.0; NaCl 0.1 M) in the absence and presence of applied magnetic field (B = 2, 4, 6 and 8 T) obtaining the lifetimes shown in Table 1 and Figure 1