Magnetoelectric effect generated through electron transfer from organic radical to metal ion

Abstract

Magnetoelectric (ME) materials induced by electron transfer are extremely rare. Electron transfer in these materials invariably occurs between the metal ions. In contrast, ME properties induced by electron transfer from an organic radical to a metal ion have never been observed. Here, we report the ME coupling effect in a mononuclear molecule-based compound [(CH3)3NCH2CH2Br][Fe(Cl2An)2 (H2O)2] (1) [Cl2An=chloranilate, (CH3)3NCH2CH2Br+ =(2-bromoethyl)trimethylammonium]. Investigation of the mechanism revealed that the ME coupling effect is realized through electron transfer from the Cl2An to the Fe ion.Measurement of the magnetodielectric (MD) coefficient of 1 indicated a positiveMDof up to ?12% at 103.0 Hz and 370 K, which is very different from that of ME materials with conventional electron transfer for which theMDis generally negative. Thus, the current work not only presents a novel ME coupling mechanism, but also opens a new route to the synthesis ofME coupling materials.