Magnetic field effect on the photochemistry of chromium complex

ANZANI, ANGEL F.; BAZÁN, CLAUDIA M.; GARCÍA, PABLO F.; BURGOS PACI, MAXI A.; GERARDO ARGÜELLO

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Año: 2020 vol. 398

1010-6030

The magnetic field effect (MFE) on the emission spectrum, phosphorescence lifetime and quenching by phenolswere investigated for the tris(1,10 phenantroline) chromium (III) complex ([Cr(phen) 3 ] 3+ ). The reactions in thepresent study have been investigated as a function of the field intensity, between 0?8 T at ambient temperature.With the aid of a homemade magnetic field generator, changes in the emission spectrum and lifetime of the( 2 T/ 2 E) states of [Cr(phen) 3 ] 3+ in presence of an external magnetic field were observed. The emission spectrumshowed changes in their two phosphorescent states, 2 E and 2 T 1 doublets; a split and a shift, with enhancedemission, of the band located at 700 nm corresponding to the 2 T 1 → 4 A 1g transition and an intensity decrease inthe band located at 730 nm, corresponding to the 2 E → 4 A 1g transition. The phosphorescent lifetime for bothemission states, which is ∼70 μs in aerated aqueous solutions at ambient temperature, showed a decrease whenincreasing with the external magnetic field applied. The MFE on the quenching rate constants ( k q B ) for phenolswere evaluated and discussed in terms of transition state theory and outer coordination sphere complexes re-actions.